Monday, 30 November 2020

Sometimes it all goes wrong

 Argh! The last few weeks have seen all sorts of chaos here, but hopefully things are a bit simpler now.

At one stage I sat down here, exhausted and cold, and nothing worked. At that stage I just thought of giving up this hobby. Is it really worth all this self-created hassle just to prove that photons propagate?

Anyway, I did move along and get most of the issues fixed. They were, in no particular order:-

1) my computer needed to have Windows re-installed

2) EMC problems on 70cms mean a complete re-jig of the antennas

3) both my sequencers failed at the same time.

4) noise on my PC HDMI display lead was affecting several bands

Plus, my work website went down and I ended up changing the domain registration, which need not bother us here. It was, however, another layer of complexity which had to resolved quickly.

And I have to face it all without Katy, my loyal shack cat. After 18 years of enjoying the warmth of the radio room, she died recently. Sure she had a good innings, but I really miss her.

Katy in charge, back in 2007.

It should not be necessary to make a fresh installation of Windows these days, you are supposed to be able to repair it while leaving everything intact. That does not work when the fault is one which prevents the repair working, and it also stopped security updates and other useful things. So it had to be done.

I have now reverted to separate 2m and 70cm antennas, and these are on my CUG mast rather than the Tennamast where the dual bander was before. Before this could be done I had to recalibrate my Yaesu rotator and run a test to see if it is accurate enough for moonbounce work (it is, just). My old 4m/6m Vine antenna is now on the Tennamast. The new arrangement is better in various ways, and worse in some other ways. All the connections on all the leads coming into the shack had to be changed. We shall see if it fixes the EMC problems but it certainly seems to work fine for 2m and 70cms, so far.

Due to the sequencer problem I had to rely on the IC-9700 for 70cms instead of 2m, because it has a built in sequencer and DC supply for the preamp. So the IC-7100 and the IC-9700 had to be swapped until the sequencer could be fixed - which it now is - so then it all had to be reversed again.

The display noise thing is a big problem. I have a super-wide LG display which I had to throttle back to standard width which meant the screens did not fit properly any more. I had to move all the sceens to different displays. After a lot of work I have just now reached a reasonable solution thanks to a heavily screened HDMI cable.

Effect ... at one stage ... all the rigs were moved to different coax lines feeding different antennas and showing up on different screens. All the settings in WSJT-X had to be re-entered. All the backed up logs and copies of circuit diagrams and manuals had to be restored to previous places on the PC. Due to the sequencer failure, nothing worked on 70cms until it dawned on me to swap around the radios again, which was more work.

Moving the antennas was started lacking in any strategy. I kept doing things without realising the consequences, and then I had to redo them or change them.

I got the initial antenna swap done, involving taking down two antennas and replacing them with three others.

And then I discovered that in one case I had put the wrong antenna up (how do you do that?). 

And then a change of plan meant that one (that had been changed already) would have to be changed again. 

And then it was decided to swap two more between one mast and the other.

And then I discovered that I had put one of the elements in the wrong place. 

Repeatedly I had to leave the mayhem in the shack and go outside into the cold to work on cold metal tubes with frozen fingers. This was either because I had not been thinking any part of it through, or if I had I had not thought out the best way of resolving the plan as a whole.

GM4FVM in full winter gear (hoodie, Caravan Club fleece) re-orders antenna elements

So as I said, I sat here at one point, back in the shack, all alone, and wondered - is this hobby worth it? Have I relied too much on computers and gizmoidery and forgotten the basic joys of this thing we do. Is it not supposed to be fun rather than a to-do list as long as your arm?

Re-installing Windows from scratch causes mayhem if you use a lot of data modes, control your rotator from your PC, measure your power and SWR on your computer ...

The answer of course is not to do all those things. If I just had a radio plugged into a length of coax, as I had in 1974... 

On the other hand, sure I could turn my rotator by following moon charts, but I find it easier to aim it following the simple readout on WSJT-X. In fact, I just click a button marked "Tracking" and they both do the following themselves instructed by the rotator software, leaving me to think about more weighty matters.

Separate 2m and 70cms antennas have replaced the dual bander

I do it the way I do because that is the type of radio amateur I want to be. Sure, it means that sometimes I can be let down by the technology, but in my view fixing it allows me to learn how it works. And when it does work it is brilliant, in my rather skewed opinion.

On the up side were contacts with NC1I and DL7APV on 70cms EME, plus emails from both of them, which was nice. Also, the new arrangement, whilst it is worse for 4m and 6m, may allow for better antennas on 2m and 23cms in the future. I could not do that before due to space constraints.

I cannot deny though that this has left me drained. At least once I did think that I could just stop there and then, and take up quilting instead. But Swing Out Sister and George Gershwin combined to revive me.




Friday, 6 November 2020

A bit more moonbounce, at last.

I am not a fan of high power. I do dabble with it, but I do not routinely run full legal power.

I can see, however, that in certain situations on VHF there is no alternative. In particular this applies to scatter modes of propagation, such as aurora, aircraft and meteor scatter and Earth-Moon-Earth (EME or "moonbounce" as I still keep calling it).

Recently I have been complaining that my maximum 70cms power output (65 watts) is a bit low for moonbounce. I am astounded, of course, to have worked anybody on 70cms moonbounce with that sort of power. When you add to that the path loss over 200dB, plus the vagiaries of the moon and the almost total lack of activity at 70cms, then it is surprising that I have a set of results to point to at all.

To make EME work you need to reach a budget of power and sensitivity which is pretty marginal at 65 watts. If, by the use of suitable equipment at each end you can reach the budget you can have a QSO. If you fall 1dB below it nothing happens at all. If you are on the margin, strange factors like Faraday Rotation, polarisation incompatibility or the Moon's variable distance can leave you with days of listening to white noise. On any one day you can look at the data and try to work out what budget of power you need, only to find that some obscure issue is preventing anything working. It helps to have some power in reserve.

But when it does work --- it is amazing. I have done very few things in amateur radio that have been more satisfying.

To reach your budget you can run a huge amount of power, have superb receivers or have massive antennas. Ideally all three. Or, in my case, none of these. To manage I use the same strategy as hundreds of other amateurs, I run a modest station and leave it to the big guns at the other end to provide the huge power level, the super-quiet receiver and the massive antenna. They don't mind, they love to work people with simple systems - it proves to them that their money was well spent.

Nevertheless, 65 watts did wear me down a bit. On a couple of occasions I heard stations who could not hear me. Mind you, they were using a kilowatt. The issue here comes down to having a balanced station. Do I transmit a signal comparable to my receive performance? Can I have a reasonable chance of reaching everyone I can hear (or hearing everyone who can hear me)? Of course, some stations will be out of balance too, but relying on them all to have super receivers does not seem too sensible. These people will have designed their station on the assumption that anyone calling them will have a reasonable set-up (whatever that is).

I have had a great time on 65watts. I would not wish to put anyone off from trying that sort of power level and you can work several stations using that approach. But I have bought a new linear. With a lot of inner doubts, I moved on and bought a Tajfun 1000 2m and 70cms amplifier. I had doubts because this has cost me more than any item I have ever bought for amateur radio. 50% more than I have ever spent before. 

It is broadly the same price as the IC-9700 (which I didn't buy, but would otherwise have been my most expensive item). Ouch. I will say more about it once I have put it fully to the test. Let me say that it claims to be able to run about 300W of data on either 2m or 70cms, though on 2m you do not have a low pass filter - luckily I already have a 2m bandpass filter.

The reason why I went for a 2m and 70cms amplifier was that, for some reason, I do not trust my 2m Gemini amplifier. Look back in the blog if you want to know why. I now have a hefty backup.

Tajfun 1000 2m and 70cm linear amplifier

I will have a better photo and more explanation about the Tajfun later. Early signs were that it is very happy running the 200W I expect to run. 300W on JT65 looks to be about the limit, which is exactly what it claims to be able to do.

So my 65W was about 12dB below those superstations running 1kW. 200W would raise me to -7dB, an increase of 5dB. In many cases that could be enough to make me heard - frankly even 1dB can be enough but you just never know with all the variables. If it was borderline I can now even muster another 100W which would add another 1.6dB.

Only time will tell if adding 5dB by running 200W will make much difference. This was a big expense and I am selling off one or two nice things to be able to afford it.

In normal operation on tropo contacts I doubt if 200W is really necessary. Where it may help is when I need to attract the attention of a station who is beaming away from me. It should help with marginal aircraft scatter contacts too.

What I am trying to do here is to bring my power more into balance with my receiver. I do not think that I need to go beyond 200W to do that on any band.

So I went on near moonrise and moonset to see what I could hear. 


I spent a very frustrating week thinking that I had lost my touch. I tinkered with the settings on WSJT-X, I footered with coax, I meddled with the sequencer, but of course nothing changed. A linear is no use if you cannot hear people. I thought I had wasted my money.

Moonbounce is very variable in the sense that you see crowd behaviour. Stations flock to it when conditions are right, when the moon is nearest, and at weekends. Of course, I was trying at the wrong time.

On 4 November I looked on 70cms at moonrise, nothing, then watched the highlights of the previous day's Vuelta cycle race from Spain on the television. Then once that was over I checked again, still nothing. The only small chink was that I could hear Anatoly RK3FG on 2m. I did not call him because I had already worked him, and anyway it was 70cms I was interested in. That was the first EME station I had heard in weeks.

After watching "The Great British Bake Off" (isn't that EXCITING??) I wandered back to the shack intending to shut things down. Anatoly was still coming in on 2m, 2 hours after I first heard him, during which time the moon elevation had gone from 1.5 degrees to 15 degrees. Not likely to be much doing now as 15 degrees is surely far too high for me to reach with an antenna fixed on the horizon. It would need an elevating antenna to do that. Or would it?

Even more suprising was to hear Dima, UA3PTW, on 70cms. I immediately called him and we worked easily. So the linear works. Perhaps my money is not wasted. A new country on 70cms (Russia), and a new square of course, plus a new "unique". Moonbouncers claim uniques they work a new station. I had worked Dima before but on 2m, not on 70cms. Very nice.

It did not quite go according to plan because Andrew, G0JCC, was having a conversation I had not noticed on the N0UK moonbounce bulletin board with Dima. Basically Dima was encouraging Andrew to give him a call, during which I had waded in with my big muddy tackety boots on and called Dima. Ooops. Apologies to Andrew. Andrew runs a comparable station to me but has better antennas - which is perhaps a better way of achieving the same aim of putting a bigger signal on the moon.

So when I popped up on the board to apologise to Andrew I attracted the attention of Anatoly who asked for a contact. I do not know if he knew I was on 70cms, but I thought I should make the best of it and call him on 2m. That contact was also completed straight away with no problems.


144 (red) and 432MHz (blue) contacts at GM4FVM 4 November 2020

So for that day, 4 QSOs, 3 squares and 2 DXCC. Best DX, UA3PTW in KO93 at 2553km. Not bad for 70cms, when you consider that the round distance via the moon was a bit over 800000km, not actually the apparent 2553km. 

All this proves that the new linear works. I could hear both stations on the loudspeaker. I must remember that I can work people at 15 degrees of moon elevation, even with horizonally fixed antennas. It is worth checking in the shack during breaks between TV programmes, even if all you expected to do was to turn everything off. Dima came straight back to me after my first call, he was not expecting it, so I am being heard. G0JCC worked Dima too, so I am on a pretty good level of competence if I can keep up with Andrew (this is the first time I had such a direct comparison with another station).

This much I have learned.

Next two days of listening at moonrise and moonset produced ... nothing.

I am worried about that, which shows that I may have learned nothing.

But, hey, the propagation to the Moon is always better at the weekend. And this is Friday!




Friday, 9 October 2020

New extension cable for my Tennamast.

WARNING: If you do this please observe safety precautions. Follow the Tennamast instructions and contact them if in doubt. What follows is what I did freestyle myself. The Tennamast instructions have arrived and are shown at the bottom of this posting. Note that they suggest doing things in a different order. Stay safe whatever you do.

GM4FVM Tennamast - succesfully re-cabled and fully working again (vertical in the foreground).

I had a plan to refurbish my Tennamast. It has been up for over ten years and I was aware that it could do with some attention. The plan (plan - well plan is a putting it a bit strong) was to strip it down, check the cables and pulleys, replace where necessary, clean the winch parts, take back the winch bodies to bare metal and repaint, lubricate the mast and rebuild.

During the Covid period I cannot summon any of the local like-minded amateurs to help me with the heavy lifting. Not that there are any locals who care about VHF-DX anyway.  A plan like that needs good weather too, as otherwise the whole thing needs taken apart and brought into the dry to work on it. 

It is possible for me to lift the mast. I picked it up and carried it when putting it up. I supposed I could take the car out of the garage for a while and work on it in there. If I took the antennas off the top pole that would break their waterproofing seals and they would need to go into the garage during such a long job anyway. So I was not about to do it right now. Next Spring seemed like a good time.

I started to notice trouble recently when I stabbed myself on the extension cable. I do not suffer well, so what really happened was that I pricked my finger on a frayed wire which had sprung out from the cable. Not quite a stab, but it hurt just the same. 

This did not particularly bother me much at the time, but the cable then frayed further and started to unravel in both directions. The overall strength of the cable was probably not much reduced, but this type of thing is the start of a chain of events which ends eventually with the cable giving way. So I would need to take action sooner than I had envisaged.

It has to be said that even if the cable did eventually give way, as it the extension cable and not the tilt over luffing cable all that would happen would be that the two sections would telescope together. If it did happen that would probably not be sudden. Most likely the cable would unravel, stretch, and lengthen, which would be obvious as it would no longer extend properly. But you have to be safe and if there is any weakness I would rather change the cable. Anyway, there would be less chance to stab myself with a new cable. 

Strands of wire peeling off the extension cable (seen after removal)
Stuff happens. Ten years is not bad for a cable. I raise and lower this mast a lot. As it is normally down by default, it is usually extended and lowered twice a day. I have read that some people get twenty years out of a cable, but they seem to leave their mast either up or down most of the time (like my CUG mast).

October isn't the best time to do this and in the event the original plan never happened. As usual, something else happens. I decided to move my refurbishment forward and start now, but it turned out to be a bit less comprehensive.

I ordered a new cable and pulleys from Tennamast. I did not need to buy the Tennamast replacement cable as I could have bought similar cables and pulleys more cheaply at the ship chandlers in nearby Eyemouth. I bought the Tennamast ones for convenience. The cable has a loop neatly made at one end and the correct size replacements bolts and spring washers. I did not think that I needed the bolt and washers, but it turned out that I did. I could not see how the top pulley had fared and it probably needed replacement. I did not want to be stuck in the middle of the job unable to source the right sized pulley.

Anyway, due to a slight mix up at the far end, the cable arrived without the pulleys. Also late were the instructions for changing the cable. I found a set of instructions on the internet from GD3YEO (here) but that was for a three section mast. Having looked at that I realised that the two section mast might be lower but it is much simpler to work on.

In any case, GD3YEO's experience encouraged me. At this stage I only had the cable and I could wait for the other bits. However, it was a nice day, so why waste the weather? I decided, at 13:00, to spend the afternoon starting the long refurbishment process by taking down the antennas, masthead amplifiers and rotator, storing them in the garage in preparation and sealing the coax ends against the rain. Then, when the other bits arrived, I would be ready to start my task. The downside was that as the year draws on the chance to put the thing back up would get less, and I might get stuck with it in the garage.

It wasn't to be like that. When I got outside I hatched another plan. I wondered if I could take the antennas and preamps off as one piece and not remove the coax and seals. Would that be too heavy for me alone to lift off in one go? No, as it turned out. Then I took off the rotator and left it connected. 

Given that I hoped to have an hour or two of good weather, why not try to change just the cable itself? I reckoned I would have to work alone because Mrs FVM has injured her rib, and anyway she was working from home to make some money to pay the shack electricity bill. She said she was "busy".

I was a bit surprised to find, once I removed the top and bottom mast sections from the rotator, that the SPID rotator bolts had cut their way into the thick wall tube I was using. I had been having a problem with the SPID losing alignment (more on that some other time, but I have solved it). During that period I tightened the bolts very tight to avoid any turning in the wind. 

The SPID locator bolts had cut into the alloy tubes
Although this extra tightening proved unnecessary, because of it the bolts were cutting their way into the alloy tube. This is a better outcome than distorting the tube, which was what I had feared might happen. Anyway, it looks OK to leave it as it is. Oddly enough I had considered making one or two holes in the tube to securely locate the bolts, but that seems to be happening without me using the drill.

Tennamast recommend steel tube but I go for lightness ...

Without the instructions I was flying blind, but why not try to press on? If anything resulted in me getting stuck I could just take off the coax, park the bits in the garage, and wait for the other parts. 

By various dodges I was able to partly extend the mast, tip it over, loosened (but did not fully remove) the stop bolt, undid the upper pulley bolt enough to remove the top pulley and then pulled the top section out of the bottom section.

Upper mast section removed, revealing corroded cable bolt

It was now clear that the bolt and nut holding the cable on to the upper section were corroded and slightly loose. The spring washer had gone rather limp. The replacement cable had a new bolt and nut, plus a new spring washer.
Fitting the new cable calls for three hands, including one for the camera

GD3YEO's report suggests this an even harder task on the three section mast.

The photo shows the stop heel on the bottom of the upper mast section. The stop bolt is mounted in the middle of the lower section, and thus passes the cable nut along the centre line of the mast as you crank it up to maximum. The significance of this became apparent later. Anyway, there is only one way to put the mast back together as the heel only goes in one way if it is to fit past the pulley, never mind catch on the stop bolt.

At this stage I pulled the new cable through with the old cable. This turned out to be important, as it meant that the cable was in place before putting the pulley back. It was clear to me which way the cable went over the pulley and down the lower section. Later I found out that the Tennamast instructions suggest doing it differently.

New cable simply passed through old cable loop, bound up and pulled through the mast.

As the new top pulley had not arrived yet I took the old one and washed it in soapy water to remove oily deposits. Tenna use nylon pulleys and it looked reasonably OK after ten years. I will replace both the pulleys at some other stage.

It gets a bit fiddly now and I may have got something slightly wrong which I had to correct later.

I now pushed the upper section back into the bottom section far enough to leave a loop of wire at the top to thread round the top pulley. I then put back the pulley on its bolt and the stop bolt. I would probably have been better to leave the stop bolt working but a bit loose until the cable was through the pulley and pulled really taut.

Once the cable was over the pulley I pushed everything together, checked that I could not pull the top section out of the bottom section, and turned it vertical for tests. Everything was working but it seemed a bit stiff. When fully up the top section jammed slightly, but with no weight on the top this was not a complete surprise.

When I turned the mast vertical I heard something sliding down the inside of the tubes. This was complete red-herring, and probably a stone or something irrelevant. I panicked, thinking there might be some sort of bush between the top pulley and the bolt, as there was a lot of play in that (though I had checked before and I could see the top pulley turning). 

So I phoned Tenna who reassured me on the top pulley issue. However, they said that the only likely issue I might have would be if the cable had become trapped on the "wrong side" of the stop bolt. It should run directly up from the bottom pulley to the top pulley, passing the side of the heel on the top section as it went, over the pulley and down straight to the fixing point. D'oh, of course. They advised me to get someone to push the top section in and then loosen the stop bolt to allow the cable to fall into its proper path under tension.

I decided that this was serious enough to call Mrs FVM away from her work to help. She found a ten minute gap and struggled against her injury into the garden to help. With only one side of her body usable and with great pain, she pushed the mast down while I loosened the bolt. I thought she could have been a bit more cheerful about it, but there was a "twanging" sound as I undid the stop bolt so it seemed to work. Anyway, I let her go back to get on with whatever it is she does.

After that it seemed to run very freely. I use a battery powered drill to work the winches, though it was not fully charged as I was not expecting to do this job right now. I had done so much work that both the drill batteries were back on charge and so I ended up using a mini electric screwdriver to tilt the mast back and forth and raise and lower it. Even though there was no weight on the top this was a good sign. If a puny electric screwdriver can wind a mast up and down it must be running freely. 

I lubricated the mast sections and did various tests. It was clear that there was no danger of the top pulling out of the bottom section (it is fail safe, even if the top bolt failed the heel would catch on the pulley). Anyway, the cable could not pull itself higher than the pulley which is inside the bottom section. Better to check everything anyway. 

It was great to see the nice new cable, even in my now rusty and dowdy winch. The refurbishment still needs to be done later, but everything has been checked, cleaned and lubricated, and nothing amiss was found.

Nice new cable in my rusty old winch, and still with original bottom pulley.

After that I slotted the rotator back, then the antennas and preamps, which were still on the top pole. After a few quick tests it was clear that everything was working.

I would estimate that the whole job took 90 minutes for the mast part. Taking the antennas and rotator off and then putting them back on took over an hour because I left them connected and they were heavy for one person working alone. However, doing that avoided resealing the coax.

It saved time, but keeping the antennas and so forth on their pole made the lifts very heavy for me alone. I had a sore shoulder for a couple of days. Nevertheless, the job was done almost entirely single handedly.

I did not set out intending to get the whole cable job done in one afternoon. That idea just emerged as I worked. Doing it this way means that I still need to do some work on the winches and replace the pulleys at some later stage, probably next year. But I have removed the weakened cable and it taught me the detail of how the mast works. I would be happy to work on it again.

Tenna were very helpful. The tip about checking that the cable was on the right side of the stop bolt was really important.

The two pulleys and the instructions have now arrived. The instructions show a different order for doing things and are posted below. As usual click to enlarge any of the images.

My Tenna mast is sturdy and well made. I rather enjoyed taking it apart and putting it back together again, even if the job is not complete yet. Now I know that the old frayed cable is not going to stick into my hand and "stab" me.




Thursday, 1 October 2020

Main and sub band USB audio output with the IC-9700.

Two postings ago (here) I explained how I was collecting a second audio stream from the IC-9700 to route to a second decoder in my computer, allowing dual band FT8 (etc) decoding.

I did this by using an analogue audio stream and it proves that it works.

I had read in a review that the IC-9700 creates one digital stream for the computer via the USB and that any second stream for the sub band would need to be taken out by analogue audio. I believed that when I read it. The Icom manual said nothing about it at all, and certainly never suggested that a second audio stream was available via the sound card and USB.

Imagine my surprise then when Greggor posted a comment on an earlier posting in this blog here to say that it is possible to get both streams via the USB. Greggor's comment was:-

Do you mean you can't get the sub band audio through the inbuilt sound card ? By default - windows sees the inbuilt sound card as a MONO microphone. If you go into the advanced audio properties and force this to 2 channel - you will have main and sub coming through. Left & Right.

Yes, I did mean that at the time, but you are right, this is possible, and I have now done it. The link given my Greggor sets this out. I did it my way by working it out myself before reading the link, just to see if I could do it. I could do it, and it works. I explain what I did below. Thanks Greggor.

First, I read all of the IC-9700 manual and advanced manual. There I could find nothing to say that this was possible, nor anything else about the audio output via the USB. The whole subject is missing. I suppose this may be because Icom are not responsible for Microsoft/ Apple/ anybody else's operating system, our computer layouts or our USB drivers (though they do provide USB drivers). If that had been in the manual I might have noticed it by now.

However, I am not going to let Icom off that easily. They did not need to understand anything about my computer to indicate in the manual that this was POSSIBLE. All they needed to say is that two digital audio streams exist, or are enabled via the sound card and USB. If that is in those manuals I cannot find it.

This second audio feed has been coming out of the IC-9700 via the USB for more than a year, and I have been ignoring it because I did not know it was there.

Moving on, once Greggor pointed this out I set about proving it my way. That means I understand how to do it. As usual I went to Control Panel and selected Sound .... (click on the images to enlarge them if you need to)

"Control Panel" in Windows with the "Small Icons" view.
As always I view Control Panel in "Small Icons" view as it makes it easier to see everything plus I am old enough to remember when it always looked like that. You can get to the sound settings other ways, but this is the way I do it. I like defaulting back to Control Panel as it gives easy access to both "Sound" for this type of thing and "Device Manager" for COM ports and lost USB connections.

OK, selecting "Sound" allows me then to select "Recording" which is where the audio comes in, and then the USB input I am using for the IC-9700 - in my case "Microphone USB Audio". I then selected the "Advanced" tab where I found that Windows has by default selected a one channel audio stream. Change it to two channel, in my case "2 channel, 16bit, 48000hz (DVD Quality)". I clicked "Apply" and I had enabled main band on one channel and sub band on the other channel.

Selecting a two channel stream in the "Advanced" tab for the USB sound card input

Then I shut everything down in the Control Panel.

Although I use Windows, I expect that Apple or other operating systems have similar option screens.

My next thing to figure out was which channel was which. Effectively we are using a stereo sound stream for two different signals. One band is "right" and the other is "left".

A quick bit of juggling showed me that, for me anyway, main band is left. In WSJT "Settings" that worked when set to "Mono" by default, but I set it to "Left" and it also works there.

Channel selection in WSJT-X - Input "Left" or "Mono" both gave me main band.
As my sub band decoding is done in MSHV I needed to set it up to right channel. That setting is in "Options" then "Sound settings". Just click "Right Channel".
Channel selection in the MSHV Sound Settings tab
Job done. Not only does it work, but it works better than the analogue lash-up, and saves another sound card and cable, plus I get my on-board loud speaker back. By avoiding a digital- analogue- digital conversion there is less noise.
GB3NGI on 144MHz via the (now-digital) sub-band

So now thanks to Greggor I have a fully digital 2-band decoding receiver. In my case this is 144 and 1296 MHz bands simultaneously. You could use any two bands, but not two frequencies in a single band.

The manual does not say it is not possible to have two digital audio streams, it does not say it is possible, it just does not cover it at all. Yet there are pages and pages of irrelevant bull-crap about logging what speed your radio is moving at, or what height the receiver is, while surely the IC-9700 is more likely to be used as a fixed DX, moonbounce and satellite transceiver. Still, you never know - I might take up using DStar repeaters from a hot air balloon. That is the obvious next step for me to take in my radio journey. 

If I was in a hot air ballon I might be able to work Montrose (read the whole blog history to understand that one).

How any cross-band digital mode operator could have worked efficiently without this knowledge I do not know.

So thank you to Greggor and I have now got this resolved and I am back to an all-digital system.

It almost seems that the S/N on the separate main band stream is better than the figures on the mono settings for the single mono digital stream. 

Surely I am imagining that.




Tuesday, 29 September 2020

Fixing my Gemini 2 linear amplifier

OK, it is four weeks now since I restored my Gemini 2 linear amplifier. By this stage, after 141 QSOs on those four weeks, I think it is working again.
Gemini 2 at GM4FVM (plus 1296 linear, PTT relay, and bent paperclip for resetting phone)

"Fixing" is the word I used in the title. Not exactly repaired, because I did not put it back the way it was, but "restored". I am using it again even though it is not as it once was.

I have had the Gemini 2 "300 watt" linear amplifier for two and half years now. For the first year it worked fine. Then it developed a fault which caused it to break down four times during the next year. And again after that.

The fault always came on the same way. The amplifier would trip with an SWR fault, even though no fault existed. I could simply restart it and then it ran for a week or two, and then tripped again. And then again after a week or so. And then every day, and then every few minutes, and then it just tripped out all the time. 

It had a two year guarantee and during that time I did not think it was right for me to try to solve the problem myself. Any meddling would just invalidate the guarantee. Anyway, various suggestions were made implying that I had done something wrong, such as it might be the centre pins of my N-type plugs, or my driver rig. It wasn't any of these things.

To prove that it was not something at my end I connected the linear to an entirely different set up, a hand held FM driver rig in and a 300-watt dummy load out, with different RF cables. I even changed the mains cables. It still tripped. This was clearly not a fault at my end. 

One reason I knew that it was not a fault at my end is that I was bequeathed (by David GM4JJJ) a very nice WaveNode WN-2 digital power and SWR meter which provides an almost instantaneous reading of power and SWR and it showed nothing amiss. I even took video and analysed it frame by frame. The SWR LED could be seen first glowing dimly and then getting brighter at different stages during a transmission, with the WaveNode in the same shot showing no SWR at all. I tried five different SWR meters, and none showed any problem.

WaveNode WN-2 - superb SWR/power meter (but very expensive!).

The WaveNode uses outboard sensors, and after it arrived here I added several more to cover all the bands I use. I cannot see how it could not be taken seriously. After all, it was supplied by the same shop as the Gemini ...

I returned the Gemini to the maker several times under guarantee. Sometimes it came back with no fault found but it still did not work here. 

Other times it came back with work having been done and an explanation. This was the solution that eventually got it working again for the first time, explained thus when it came with this email:- 

"I had a hunch what it was and it proved to be correct. 

The directional coupler pick-up bridge circuit feeds through two 75R 0803 SMD resistors - one for fwd and one for rev. 

The rev one was showing big swings in resistance with temperature and the thermal camera was picking up a bigger variation in temp (as it heated up the resistance was lowering to the current was increasing causing more heat and so on). 

I have replaced both these 75R resistors and the amp has been on soak test now for an hour at 150W out with no issues." 

So this was my clue as to what was wrong too. Well, it was actually exactly what was wrong. I had this clue to go on, and he sent me a photo of the resistors:-

Photo of one of the SMD resistors sent by DXShop (looks rather small, as they do ...)

Replacing the overheating resistors with more of the same solved the problem for a while. 

I did wonder if there might be another minor fault in the control board which receives the SWR measurement, making it more sensitive. But changing the resistors had worked - for a while. Until the Gemini started tripping again after another few months.

After yet another trip back under guarantee (the fifth trip back I think) I got this message:-  

"As a precaution I have replaced the directional coupler components. If it still trips then there must be some issue external to the amplifier that is failing under rf load."

That was a strange comment. If changing the components fixes the fault that suggests to me that the components are at fault, not some issue external to the amplifier. That is a very strange bit of fault finding - change a component and if it fails again then deciding that it is something else at fault. And blaming something external which seemed to me to be unlikely to be causing a resistor in the directional coupler to overheat.

Well anyway, there wasn't some issue external to the amplifier causing a problem, apart from the way it was being repaired. 

I felt sure that keeping on changing the resistors which keep on altering in value was just putting the problem off for a while. However, by repetition this had occupied the entire 2 year guarantee time and "some issue external to the amplifier" means it is my problem now. 

Sure enough, it ran for a further three months before the same fault happened yet again. Of course it did, as nothing had changed. Just keeping on doing the same thing (changing the resistors for more of the same) and expecting a different outcome is the daftest way to try to fix a problem - unless of course you just want to let the guarantee run out and solve the problem that way. 

Another way I knew the fault was not at my end was that during the periods the Gemini was away being "fixed" under guarantee I was using the excellent Microset SR200 linear amplifier. No SWR fault there. At one stage when the Gemini came back I was rash enough to think that it would work for an extended period and I sold the Microset. When the Gemini failed again I acquired an RM Italy VL-250. The Microset SR200 was good, the RM Italy VL-250 was excellent. The VL-250 has a very fine protection suite including SWR protection - and no fault showed up there either. That was because there was no fault at my end to find.

So when, three months after it came back for the last time from repair under guarantee, it failed again (of course). I just put the Gemini 2 on the shelf and plugged in the RM VL-250 and tried to ignore it. 

There, sitting on a shelf, was a nice piece of kit which I could not use. Obviously I was going to do something eventually, but just then I was really fed up with it. 

A couple of months later I calmed down and started to think that the Gemini needed to be restored. 

I read back over everything that had happened. I decided to assume that it was true that the two resistors in the directional coupler were overheating and varying in value. One thing that seemed to be supporting that idea was that the output meter on the Gemini had started to work erratically - and it is powered by the directional coupler too, albeit by the forward power circuit. If changing the resistors worked for a while each time then perhaps that is the only fault, and the power meter is affected in the same way. For the moment I decided to put my doubts about the control board to the back of my mind.

I poured over the Gemini circuit diagrams and read the manual backwards and forwards. I opened it up and examined all the things I thought I could do. It seemed that I had four options:- 

1) Turn off the protection by turning down the potentiometer on the control board (which would stop over-drive and over-temperature protection too) 

2) Replace the SMD resistors in the directional coupler with devices which could withstand the heat/current 

3) Simply disconnect the directional coupler and run without any SWR protection, leaving the other protections in place 

4) Do (3), but add some outboard SWR protection of my own. 

 I rejected option (1) as being too risky. 

Option (2) appealed, but I still had some little bell ringing in my head that the board might be off specification too. I may do this later and restore the Gemini to more-or-less original condition but for now I will not being doing that. Too many imponderable possibilities.

Option (3) was possibly an immediate solution to see if that solved the problem. Although I have used lots of linears over the years with no SWR protection, I felt sure that Murphy's law would step in and blow this one up if I ran it permanently without any protection. I had no strong reason not to do it, and I think it should be safe enough. 

BUT, option (4) looked the easiest way of getting the Gemini working again and having some SWR peace of mind. 

I should perhaps say that the Gemini 2 has NEVER tripped due to high SWR when there really was an SWR fault. It has tripped dozens and dozens of times, but only as a result of this false trip issue. Despite this I though I should do SOMETHING to protect against high SWR, simply to put my mind at rest. 

When David JJJ became silent key he left me his WaveNode, as mentioned above. David and I had talked about my false SWR-trip fault and he was as worried about it as I was (he had two Gemini linears himself). Now, whether he had thought about the possibility of neutralising the SWR circuit and using the WaveNode for protection I do not know. After all, when we spoke about this fault it was still supposedly being "fixed" by the makers. Anyway, the WaveNode he left me has an SWR protection circuit. There is a trend here - everything David left me has been useful, even if I could not work out why he left them to me when they arrived.

So we had two fairly simple tasks:- 

First complete Option 3) - disconnect the connection between the directional coupler and the control board (then test everything works) 

The complete Option 4) - rig up SWR protection from the WaveNode. 

First: cutting off the on-board SWR protection 

This is pretty simple, or it should be. The wire from the directional coupler uses the multi-pin header plug on the W6PQL control board. Despite this being fairly simple to disconnect I managed to disconnect the wrong wire three times. 

Getting them back in once removed was tricky. Use a commonly available crimp tool "under $30 on Amazon" says W6PQL. Anyway, none of the crimping tools I had worked and eventually a home brew method using a screwdriver and extreme force did the job. 

Did I ever mention that I am colour blind? I am not the right man to send on a job to a 20-pin plug to find any particular wire. I am bound to pick the wrong one. Not that I actually needed to do that, as I could have just counted the pins (bet you would have started counting at the wrong end Jim).

The 20-pin header plug on the W6PQL control board (colourful, eh? I would not know)

Talking about using the wrong tool for the job, one day I happened to meet one of the workers who helped us built this house. He was in the village shop. As part of our discussion I asked him how he coped with the cold, wind and snow at the time. "I find that large quantities of psycho-active drugs do the trick. Washing them down with Buckfast tonic wine helps too". The shop assistant nodded her agreement knowingly. 

I did not disconnect the forward power line to the power meter on the front panel, which perhaps I could have done at the same time. 

I found it easier to take the W6PQL control board out each time while working on it. It is screwed to the right hand side of the Gemini case and hemmed in by other components.

Having carefully insulated everything which had been disconnected, I put the linear back in its case and tested everything with no SWR protection. Unlike before, when it tripped immediately, it all worked perfectly. It worked fine for three days before I set up the SWR protection. 

Then setting up the outboard SWR protection. 

Pretty simple too. The WaveNode has an on-board relay which trips at a pre-determined SWR level which you can set in software. 

The WaveNode monitors four power and SWR levels at once (in my case, 6m, 4m, 2m and 23cms). However, it can only do SWR protection on one band at a time as it only has one physical relay. For the sake of simplicity and to avoid any confusion later (hopefully) I moved 2m to monitor One, and set the SWR trip level at 2:1. This is in fact a tighter trip level than the Gemini had initially.

WaveNode monitoring 2m (band 1), set for SWR2:1 (actually it is 1.132:1 in this setting).

 The physical wiring looks complex but is pretty basic really. 

Using the WaveNode to monitor the Gemini SWR

For the sake of clarity the diagram leaves out the 24 volt relay which switches the IC-9700 PTT line between the 2m and 23cms linears. That is the relay you can see in the first photo. Well, not just for clarity: it is wired in the wrong place. It too cuts off the 23cm linear should the 2m SWR trip work. Far too much wiring to get that right so I left it the way it is. This place is like a spider's web already without adding more wires.

The WaveNode has a three pin PC board socket on the back of the main module. Being the sort of person who never throws anything out I had a matching plug in my "computer parts" box. It was simply a matter of attaching phono plugs to that so that it matched my PTT line standards. 

If the SWR on 2m exceeds 2:1 the relay will trip and de-activate the PTT from the Gemini. That leaves the rig facing the high SWR, but it is well protected and that was always the case with the on-board protection anyway. 

I suppose that there is some risk of a cable failure between the Gemini and the WaveNode sensor, but then there is a risk of cable failures inside the Gemini too. And in any case such a fault would probably trip the SWR circuit anyway (I am not about to test this to find out).

I tested it with a high SWR at the antenna and the trip worked immediately and also gave a loud audio warning "HIGH SWR TRIP ACTIVATED" over my PC speakers.  

You could do this with much simpler and cheaper SWR meters than the WaveNode, but that was the one I had.

So finally ... 

The Gemini is restored. 

Maybe one day I will delve in and replace the two resistors in the directional coupler with high wattage and high stability alternatives. On the other hand, maybe not. 

For the first few days there was a "hot electrical" smell which suggested that the resistors were still overheating. Gradually the output power meter got more and more erratic. Then the smell stopped, the output power meter stopped working, and normality was resumed. 

I can read the output power and SWR from the WaveNode, which displays this information for all bands conveniently on my PC screen. It also shows one band directly on the readout on the WaveNode module itself.

I am left with various issues to ponder over. One reason I did not replace the resistors (again), apart from still being a bit doubtful about the control board, was that I am not sure why they were so hot in the first place. This Gemini 2 is very quiet, compared with my 4m and 6m Gemini linears. Could it be that the fans are running too slow?

I have tinkered with the pot on the control board and poked about at the secondary fan control board, but the airflow seems OK. There is plenty of hot air coming out over the PA heatsink, and the fans do accelerate as you might expect. So is it just the SMD resistors cannot handle the current? Why not?

Never mind it works, for four weeks so far anyway. 

I still have the splendid RM VLA-250, a fine 200W linear I used for many months while I was fuming about the Gemini. Should I now sell it? When I sold the Microset the Gemini failed soon afterwards. 

Surely the VL-250 is too good a device to keep in reserve. I might need it if the Gemini or its resistors start glowing red. But then again, being colour blind I can just ignore that. Would drugs washed down with Buckie ease the pain even further?

And another surely. Surely it would have been better for the maker to have changed the resistors for more capable ones when he kept getting my amplifier back for repair with the same fault? Maybe more work, but I might have been happier with him if he had done that. 

It is a safe bet that my next two linear amplifiers will be of a different make. The Gemini design is good and the price not unreasonable. The service on the Gemini was great while everything worked, but not so good when it didn't.

Thanks again David.

I do not know how you knew, but you knew.




Tuesday, 22 September 2020

Using the IC-9700 as a dual band FT8 decoder plus heaps more tropo.

 OK, TROPO - loads and loads. New squares, new countries, but more of that later.

Stations worked at GM4FVM 15 to 21 September 2020. Red pins for 2m, purple for 70cm, light blue for 23cms. It is only a week's activity you know.

That might be an image that needs to be clicked for a larger version ... not to mention the others.

Yes, it is true, I monitor several bands at once. As someone asked how I do it I hope to cover this in a later posting. I cannot listen on several bands at once because few humans can do that. However, I can have various displays on my computer screens, and I can monitor multiple bands that way. This allows me to jump up and down the spectrum and sometimes "do the treble" by working into a country on three bands in quick succession.

The object of this posting is to explain how I am using the IC-9700's dual band capability to monitor data modes (and not just FT8) on two bands at once using the IC-9700. There is nothing very startling about this - you can listen to SSB or CW on the loudspeaker on both bands. On data most people will connect the IC-9700 to a computer using the USB socket. That is fine for one band. I use the other audio output from the back of the 9700 and feed that into the computer to cover the second band.

For this purpose I picked 144MHz and 1296MHz, because I use an IC-7100 for 70cms. You can use any two of the three bands on the IC-9700. I also decided to use MSHV to decode the second audio stream, simply because it looks different and I am less likely to get confused. Getting confused is not unlikely - the IC-9700 has a complex system of VFO A/B and band and sub-band which can be very hard to fathom.

So I went for simplicity (?!). As the sub-band cannot be used for transmit, I reserved the second audio stream for decoding (listening) only. The second display is just for reading, it does not report reception to PSK Reporter. This is because I will be switching between bands and the second stream does not have CAT information. If I enabled reporting on the sub-band it would keep reporting the wrong band if I switched between bands. 

And anyway, I need to be able to get my head round it. Everything recorded on the sub-band, whatever frequency, turns up on the secondary MSHV screen. I work on the current WSJT-X screen - always. I switch between bands by pressing the upper multi-function button ("M/S") which swaps the main and sub band frequencies. The WSJT-X software I use for the main working area keeps up with the working frequency, but the secondary one doesn't. I know I can only "listen" (watch?) on the other sub-band one. When the working band is 23cms (on my left), the monitored one is always 2m (on my right), and pressing M/S swaps them over. Simples.

Main-band reception of 23cms GB3NGI beacon on JT4G at GM4FVM

Simultaneous sub-band reception of 2m GB3NGI beacon on JT65B at GM4FVM

To show me receiving both of these at once I had to use a beacon. I would rather have done it with FT8 and active amateurs but I forgot during the recent tropo lift and now everybody has gone off the air. But obviously both bands can be heard and therefore decoded simultaneously. If you wanted to transmit in the secondary frequency you just press the M/S button to bring the required band into use.

It really could hardly be simpler. To add the second decoding software you can add another "app". In my case download the latest version of MSHV, install and run it in a new folder, and connect the audio to it. For that you need  ... an audio cable with a 3.5mm plug on each end.

EDIT - I did not know it at the time because the IC-9700 manual doesn't mention it, but I could have used a second channel on the USB audio output instead of a analogue line. Thanks to Greggor for pointing this out. See here for an explanation. The analogue system described below will work, but the two steams via USB will have less noise and save some wiring. 

If your computer has a spare audio input socket, just plug the cable between the sub-band socket on the IC-9700 and the computer. In my case I did a lash-up first with a USB audio card from eBay (cost £3). That worked, though the signal/noise on the sub-band was quite poor. I added an audio attenuator (also a small sum from eBay) as that device only had a microphone-level input. It wasn't great but it proved everything worked.

Next step for me was to add a better outboard sound card - one I bought a few years ago in the days before USB audio input direct from commercial rigs. This is better quality and it has a line-level input, but it still cost less than £10. The S/N on the screen was better, the reports higher and I have stuck with that.

Cheap USB audio card with attenuator

As I say, there is nothing special about this. We used to connect our audio output from our radios to our computers in the early days of PC based data modes. Just as in those days, once you plug the lead into the IC-9700 sub-band output you will not be able to listen to the radio on that speaker (but you can turn on "listen" to the audio stream in the computer). You have to set the sub-band volume control for the correct reading on the software, in my case made easier thanks to the attenuator. But strictly you do not need to attenuator if you can balance the volume controls on the radio and in the computer (and MSHV gives you a volume control too).

And it works! I often leave the rigs running while I am out of the shack. Normally that means monitoring 2m, but now of course both 2m and 23cms on the IC-9700. I was passing the shack with my coat on about to leave when I spotted something on the MSHV screen. It turned out to be DF5VAE on 23cms - I just pressed a button and I was ready to try to work Charly. It took a few moments. His linear amplifier had failed but he was stronger barefoot. We quickly completed a contact for my longest DX on 23cms, with a new square and DXCC into the bargain. Without a second monitor I would never have been able to do it.

The same thing happened several times during the past week, and in both directions. I was on 23cms when I saw something interesting on 2m too. Why not? The IC-9700 has two receivers, so why not use them to monitor two bands at once?

Of course anyone else doing this will probably not follow my idea of using two different bits of software to decode each stream. I do this to make it clear to me what is happening - MSHV for sub-band (right hand of screen), WSJT-X for main-band (left hand of screen). I like to know where I am. 

If you are adding multiple instances of WSJT-X you need to follow the guidance on the WSJT-X website (link on the side bar of this blog). Basically you need to give each rig a separate name (I have four instances!). Maybe I will cover this in the later posting. Anyway, it is very easy just to use MSHV for this purpose. Easy, Jim, your mother never liked you doing easy. But it is, and it works for most things (but not JT4 from GB3NGI beacon as MSHV doesn't have that mode).

 Right, time for some tropo reports.

On 13 September I worked DJ8MS on 2m. That is not so unusual, but what happened after that was unusual. For the week 15 September to 21 September there was tropo every day. A large high pressure system moved in over the North Sea, and although that faded after a few days, another high from the Atlantic merged with it. Hepburn predicted it very accurately of course.

By 17 September the PSK Reporter page for 70cms was beginning to look more like the normal one for 2m.

432MHz as shown on PSK Reporter on 17 September 2020

At different times propagation moved around covering France, Belgium, Netherlands, Denmark, Norway, Sweden, Northern Germany, Czechia (!), Poland (!!) and Estonia (!!!). And while 2m was like a bear pit, 70cm was busy and even 23cms was a bit busy. 70MHz, a band which can produce some good tropo openings, was also affected. Just goes to prove it is worth monitoring as much as I can. 

Busy is not the only way to judge it, so how did I do for DX? Well, as is so often the case, things got better just before the opening ended. And then, just when you think this is going to get even better, it is over.

In 7 days I was actually operating for 21 hours and 33 minutes to work 65 squares in 15 countries. Best DX was, perhaps appropriately the last of 170 QSOs, to ES8TJM in KO18 at 1575km. Wow.

The highlights were ... everything ... , but to look at each band in turn (except 4m which had 5 tropo QSOs and 6m one on Es):-

144MHz contacts at GM4FVM 15 to 21 September 2020

Hard to know what to say about that.

97 QSOs to 49 squares in 12 countries.

I look back at the log and, quite frankly, I cannot recall some of the entries. I am reeling. I need to look more carefully at it to appreciate the individual detail as well as the whole thing.

Thanks to ES8TJM for my first 2m tropo contact to Estonia. Thanks also to HF0BW who would have got the award for best DX to Poland had ES8TJM not won it by 19km. And thanks to the rest who were making it a very memorable week.

432MHz contacts at GM4FVM 15 to 21 September 2020

56 QSOs to 31 squares in 12 countries. Loads of new squares. Thanks to SM1FMT for my best ever tropo DX on 70cm for 1359km to JO96 in Sweden. Surprised would be the word about that one. 65watts and 2.5m boom yagi. Eh? And as I keep saying, two years ago I didn't even have a 70cm antenna because I thought I would not work anyone. And thanks to OK1VVT for my first contact on 70cm with Czechia.

Let us get this straight. Unlike some (those who regard themselves as part of the Senior Service of amateur radio) I do not sit on the sidelines and wait to pounce on the choice DX like some radio-spider. I know that other operators need GM as a country, or IO85 as a square, and I like to do my bit. 

There are some choice bits in there which I would have missed had I not got involved with the masses. F6DBI is a nice bit of DX for me on 70cms. I have worked him a few times on 2m, but this was only the second on 70cms. I have not heard so much of ON4POO lately but a first contact on 70cms was a pleasure. I still reckon 70cms is very interesting. Working GM0HBK is a treat, and working DF5VAE or DL7APV is a joy. And that bag full of OZs are always interesting.

If they want to contact me, I will try to work them. How do I know - I might be the best bit of DX they have worked all year. And, frankly, these contacts are all equal value to me whatever record they may break, or not break, as the case may be. I only go on about the records because they keep surprising me.

23cms was great fun. Now I can monitor it without taking my eye off 2m.

1296MHz contacts at GM4FVM 15 to 21 September 2020

12 QSOs to 10 squares in 6 DXCC. But what QSOs! Thanks to GI6ATZ, F5APQ and PA0O for my first contacts on 23cm into Northern Ireland, France and Netherlands respectively. And thanks to DF5VAE for my first contact on 23cm to Germany and my best DX on that band at 1001km to JO64.

I had several requests to try to contact stations in Poland on 23cm and Czechia on 70cm on CW amongst other things, but none of it worked. Still, perhaps that saved them listening to my crappy morse, so it was not all bad. Plus I still have some goals in my radio life.

Sorry this article has been so long but how do you describe the last week in any other way? Now that I can monitor three bands at once and hop between them I have been able to range across the frequencies as conditions changed.

Towards the end of the opening, on 21 September, the conditions went into overdrive. There were whistlers moving up and down the band. Stations had signals which were dissolving into dust rather than forming FT8 traces. I sat and watched superstations working Finland and Latvia and just monitored them off the back of my beam. No need for me to get involved because I have neither the station nor the drive to try. Maybe I am what a certain President would call a "loser" for not wanting to plaster myself over the clouds. But how can I not be content with what I did this last week?

If you were there, I hope you had a good time too.

And if you have a log periodic ready for that IC-9700, what is stopping you getting back on?

A radio-spider? What is that? Have you gone totally bonkers Jim?




Wednesday, 9 September 2020

Some more tropo and having delusions of competence.

Sometimes I get carried away. I allow myself to be deluded into thinking that I know what I am talking about.

Maybe I am not the only ham who suffers from this.

Anyway, sometimes I believe I can actually out-think the experts. In this case the expert is the very reliable William R Hepburn, whose superb tropo ducting predictions are linked to the sidebar list on this blog.

Hepburn suggested that tropo conditions would be good here on 7 and 8 September. I looked at the weather outside, felt my bunions (always reliable in the past) and concluded that tropo conditions would not be good. (Does anyone remember the Bunnion strip cartoon in the evening newspapers? Not the same as my bunions though).

I related this unwise prediction of mine to Jeremy M0XVF as follows:-

It is blowing a hoolie here now so I cannot imagine tomorrow will be very good. Maybe further south. I live in hope though. 

I was, of course, talking total nonsense. Yes it was windy here. Also, the Reporting Scotland weather forecast looked pretty poor.

Hepburn knows best.

I do not need to know anything else about tropo, just that Hepburn knows best. I can look it up, and not go off on fantasies of my own. In this case my predictions were wrong, and his were right. Who'd 'ave thought it?

Jeremy sent me a reply that the Angus beacon was loud with him, the GB3NGI beacons in Northern Ireland "v loud indeed" and that he held hopes for conditions into Europe. He was right. There is nothing like the facts to upset my imagination.

If I do get on my high horse and think I know more than I do, I hope I can accept it when somebody else knows better. I decided to accept that Jeremy knows what he is on about and have a listen. 

I left Mrs FVM to watch some gruesome TV programme about people who suffer from unidentified dread diseases, and turned on the radio instead. Tough choice, but someone has to swerve the morbid images of pus and sores to check out the radio. Did any of them have bunions? I will never know.


 Above: VHF contacts at GM4FVM on 7 September. Red pins = 2m, blue pins= 70cm. 

Click the images to enlarge (seems to be working again).

The thing about all of these QSOs were the very strong signal reports. G3NSM in IO91 was +12dB here and gave me +07, GW8ASD was +09 and he gave me +16. Even though the 70cms contact with G4RRA took a while to complete, he gave me +08 from my piddly 65W.

NOTE TO SELF:- must do something about that 70cm power level, apart from just complaining about it.

OK, so I was wrong. What was Hepburn saying now?

  Above:- Hepburn tropo prediction for 8 September 2020.

I was beginning to think that I needed to take this a bit more seriously. The weather forecast on the TV was still showing nothing really interesting, with moderate pressure and a meandering front passing from west to east. But Hepburn also considers other factors such as the relative humidity of the air which is a crucial factor. So I guess he knows better than me.

Of course he knows better than me. He has been doing this for decades.

I needed to get up the next morning and spend some time trying to work someone. Oh dear. I am not at my best in the morning.

Next morning produced this:-

Above: VHF contacts at GM4FVM on 8 September. Yellow pins = 6m, blue = 70cm, red = 2m.

Best DX was, of course, as so often, DF5VAE in JO64 on 2m at 1001km. Even that one was +06/+13dB signal reports. Best on 70cms was with F6HMQ in JN18 at 888km. I do not wish to take away from any of the contacts, and I was especially pleased with the others on 70cms as we shall see later.

I am not sure if I like using different coloured pins on the map to show up different bands. Apart from anything else, there is no coloured pin for 70MHz. There were two contacts on 4m during the tropo opening, one with ON4IQ and the other with DL6BF. Tropo contacts of 702 and 730km are good stuff on any band, and maybe my best tropo contacts on 4m (I did work ON on 4m tropo many years ago but that was on CW and my CW is never nice for the other station).

So on 7 and 8 September 2020 I worked 33 stations in 23 squares and 7 DXCC. I concede that Mr Hepburn was correct in his predictions.

I might mention that the RSGB UKAC 70cm contest was held later on 8 September but I seemed to have done better by not waiting for the contest. I was finished at lunchtime, and the TV viewing that evening was much better than the day before (Tour de France, England getting beaten at cricket and Eat Well for Less!). I would rather watch Gregg Wallace make an omelette than listen to a flat band at contest time.

Before I leave the subject of 70cms and tropo, I want to mention that tropo also happens when there is no ducting. Combining both days when there was ducting with the other eight from the last ten days produces this:-

Above: 432MHz contacts at GM4FVM from 31 August to 9 September 2020

These are in succession, MM1FEO 484km, G4YTL 429, GM0HBK 269, G4RRA 578, PE1NMM 681, F5APQ 606, F4HRD 606, F6HMQ 888, and G4VQZ 563km. Only in the case of MM1FEO did we move up from 2m, all the rest were "random" - in other words - CQ calls answered. 70cms has certainly surprised me. For a band which I did not have an antenna for two years ago, I seem to be making progress.

Is this event over? Probably but there are usually more high pressure systems on the weather chart somewhere, even if they are still days away from reaching me. I need to watch Hepburn more carefully.

What is left of this event seems to be producing very good conditions further south and east of me. Here normality has returned for now.

This opening gave me a good chance to give a work out to my disgraced Gemini 2m linear amplifier. I have given it some surgery to get it working again. It has been out of operation for four months and it needs a good soak test before I am willing to claim it is now ready to go solo. I did use it for all the 2m contacts listed here and so far so good. I will write it up if and when I am happy it is working again. After six breakdowns I can hardly be blamed for not trusting it. Now that it is out of guarantee I feel able to do some work on it myself - at last.

I have also been poking at my TE Systems 175W 432MHz linear which seems to be terminally silent key. It needs money spent on it and I doubt if it is worth it. With such wonderful high power devices now available I an unsure whether I should be spending my cash on old-style replacement Motorola transistors. If I do get it working, it will still be an old-school linear as opposed to the latest high gain amplifiers like those from Freescale. And then there is the little matter of changing 5 transistors with surface mount components on their fingers. With my shaky old hands? New the devices, even un-matched ones, would cost more than the linear cost me in the first place, and that leaves second hand ones. Hmmm.

I hate abandoning something that needs to be fixed. Maybe it should be a project on the shelf for days when there is no tropo,

Never mind, if I can do all that on 70cms with 65 Watts I cannot be too unhappy.