Monday, 27 April 2020

The Icom IC-9700 external pre-amp DC supply is a bit odd too ...

This is more on the oddities of the IC-9700 unexpectedly continued from four days ago in the last posting which is here and then even more here. The last one has a link which expalins it fairly well.

I have to confess that I made a mistake (wot, another one after Wrong-band-gate?).

Yes, when I wrote my initial review of the Icom IC-9700 (you can find that here) I was mystified by the lack of any proper explanation of how the external power supply to power a mast head external pre-amp worked. I described it as "an issue I am not so sure is really an issue".

Well, the mistake I made was to think I had the masthead preamp supply turned on when it was turned off. The reason why I made that mistake was the same as the issue I described, the manual does not explain this well enough. Actually, it does not explain it at all.

The procedure I followed at the time to get the masthead preamp supply turned on was in fact that procedure for the IC-9100. Thanks to Andrew, G0JCC, for clearing that one up for me. I was happily turning on and off the internal preamp and assuming it was the external supply.

It soon dawned on me that something was wrong. Not that it mattered much as I was using an outboard sequencer and bias-tee system so I did not need to rely on the internal 9700 supply. Nevertheless I did check and found no voltage on the 144MHz socket and I came to the conclusion that something had stopped working. Then soon after I discovered the 23cm socket was the same. The issue went into the "to do later"pile along with various clocks computers and linears that need fixing.

It did irritate me though. An issue that doesn't matter usually bugs me for ages.

Then this weekend I got an email from John G3WZT. He had found exactly the same thing, though fortunately he took it a bit more seriously that I did. After 24 hours of mind-wrangling it finally dawned on me what was wrong. The supply was indeed turned off, not faulty. In my long experience of these things I find they never work well if they are turned off.

And ... I did not know how to turn it on.

You have in fact to turn it on in two places for each band, in other words six times for all of them, and if you press the P.AMP button you get the internal one instead which will throw you right off course. And I had been thinking that the button applied to both pre-amps (because it says so in the manual - silly me). The idea that the button turned on the external preamp power came from the way the IC-9100 works, helped by the misleading manual for the IC-9700.

There is a lot of resistance put in your way If you want to turn this supply on.

The first line of resistance is page 1-1 of the manual which says the button on the front panel controls two preamps.

The second line of resistance you need to cross is the External pre-amp control in "Connectors". You should only need to do this once.
IC-9700 Selecting External P.Amp in "Connectors"

The third line of resistance you need to cross is on "Function page 2".
IC-9700 Selecting Function page 2 after External P.Amp has been enabled for that band.

Right, so here goes.

This, I think, is the way to turn on the IC-9700 DC supply for external preamps.

1) Select "SET"
2) Select "CONNECTORS"
3) On Screen 1 of Connectors select "External P.AMP
4) Turn the DC power supply on for the bands you want to use.
5) Return to main screen
6) Select FUNCTION
7) In Function select page 2
8) Turn on EXT P.AMP.

If you do not do steps 1 - 5 then the EXT P.AMP button on Function page 2 is greyed out.

Having done this the EXT P.AMP button on Function page 2 becomes your toggle switch for the external preamp and the button on the front does that job for the internal preamp. There is no indication on the display that you have the external supply turned on, you need to rely on the button on the Function screen for each band in turn.

Now there is very little in the manual to explain what is going on here. No wonder various people are confused. The manual misses the following piece of information:-
1) that the radio has DC over the rx coax at all, because how the DC gets out of the rig is never explained
2) the voltage
3) the polarity
4) the maximum current available
5) whether it is sequenced
6) if so how much it is delayed
7) whether the delay time can be varied and, crucially, -
8) HOW TO TURN IT ON AND OFF, EXPLAINED IN A LOGICAL WAY.

Briefly, these are the answers I can cover based on my observations (1) DC bias is available on rx once you find out how to turn it on (2) about 13.8V falls to 11.7V at 330mA, (3) +ve to coax centre meaning commercial preamps like SSB and SHF products work natively (4) not sure but it runs two of my 200mA preamps on two bands (5) apparently so, but don't count on it because we are not told (6) no idea (7) apparently not (8) I have done my best above.

It is not really my job to re-write the Icom instruction manual. Without much information I can only surmise these things so please do not take them as definite.

What information they do give is pretty cryptic, as here on Page 4-1 of the main manual:-
Part of Icom IC-9700 main manual page 4-1
This makes sense to me now, but only after I know what is happening. Just a bit of info - like what this is and how it works - would have helped me enormously. And the key bit of info missing for me is that it does not say that you have to come back out of Connectors to go to Function page 2 and turn it on for each band in turn.

I think what threw me right off the track is the comment on  page 1-1 "PREAMP/ATTENUATOR KEY Turns ON or OFF and selects one of two receive RF preamplifiers ..." What? The button acts on two preamplifiers? One of two? Which? One at a time, and how does it select them? I took that to mean the button worked on both internal and external preamps depending on how you set Connectors. This was not an unreasonable assumption as on the IC-9100 the equivalent button controls its external preamp. If that was not so, where are the two preamplifiers? This reference to two preamplifiers seems to be wrong.

'Onest Gov, it wasn't a mistake, I was misled good an' proper.

Anyway I am not one to be bitter, as you all know. Oh no. Icom, also, this type of thing would have been a lot easier if you had got page 1-3 correct in the original digital manual, then updated the manual available at the Icom UK site to correct that mistake, and not left me to resort to a paper copy where you have stuck a corrected page 1-3 into a sheaf of loose papers.

It is working now. I have been able to take out my cobbled-together sequencer and bias arrangements, freeing my rats nest behind the bench of 0.32% of its clutter. I also have 47mm of freed-up shelf space. [One of those two statistics is made up, the other is true]. I can do this now because my 2m and 70cm linears both pass the DC supply through to the preamps on receive. My 70cm one does not have a DC path through it, but then I do not use the IC-9700 for 70cms.

EDIT - I discovered that my 2m DCI cavity bandpass filter does not pass DC. I know this now because the IC-9700 must check for a short circuit on the coax. When it found the short it automatically turned off the DC supply (the button on the Function page 2 screen turned to "off") and posted a message on the display warning me of what had happened. I can find no mention of that in the manuals either but at least it works. 

I have checked the sequencing and there appears to be no SWR spike on going to transmit. At that level anyway everything checks out with the sequencing. We shall see however. I hope nothing gets blown up due to faulty timing. I would have more confidence if I had some information in the manual to support the evidence that it works. So, for now, all I can say is that it seems to be OK.

I now expect emails from sad individuals saying that I am carping and that I should have worked this out at the start. OK, the Icom IC-9700 is a very good radio. This DC supply is now working perfectly well. What I am going on about is that several of us have been left confused. I thought there was something wrong with the radio, not because I am totally dense but because it is very hard to understand the way it has been documented.

There are 96 pages in the basic 9700 manual. The basic manual is just a quick start guide as there are 173 pages in the advanced manual. I would have thought that any radio that claims to be a VHF/UHF DX-capable device would make things like this able to be understood, even by me. Surely a page could have been found to give us the details?

Much help was received in solving this from Andrew, G0JCC, and John, G3WZT. Thanks both of you for setting me thinking.

73

Jim GM4FVM

Friday, 24 April 2020

The odd aspects of the IC-9700 and 23 cms progress.

I have been busy with more difficult stuff (more later) so here are a few odd tales to keep us going.

First some small success:-
A QSL for my first contact to Denmark on 23cms:-
QSL from OZ2ND for 23cm contact on 23 March
As Niels Erik says, the two previous contacts on 144 and 432 MHz were good too. In fact I would have been happy with either on their own. This was our 19th contact, but perhaps the sweetest one for me.

I do like to receive a QSL card though the post. It also shows the merit in asking people to move up a band after they have worked you. You then have a reasonable chance that the propagation will also be good at the higher frequency.

Progress on 23cms:-
I have had a bit of trouble getting out on 23cms. You would not think this given the QSL card above, but I do not seem to be having the success I thought I should. I can hear better that I can be heard. Or so I think.

After a good QSO with Jeremy M0XVF I was amazed to hear Sid, G8SFA. Of course, to confirm my doubts he could not hear me. After emails and a long phone call Sid could confirm that I was not reaching him. So more work needed.

Thanks to some more encouragement from Jeremy XVF, I have been ironing out a few problems. I had been using some back-to-back N-type plugs to get around linking various bits together (just one on each band). The idea is to reduce the rats nest of 10mm diameter leads round the back of the desk. I have become increasingly wary of these.

Some came from David GM4JJJ with the equipment he left to me. I then bought a couple more claiming "not the usual rubbish". So now of course I do not know which is which.

I got even more  concerned when bits of the waterproofing seal fell out of one and looked decidedly dodgy in another one.

Not easy to photograph without taking the thing out into the sun and angling it like a telescope. Anyway this was the best I could do with it just pointed upwards (the sun never gets overhead at non-tropical IO85, in case you wondered).

I doubt if this puts anything in peril, though they are supposed to be precision items.

So I went through and took them out and replaced them with short patch leads. Expensive but effective.

Then I tried to set up an arrangement whereby the switch from 2m to 23cms is easy. As you will know the IC-9700 does not allow differential linear switching. Also, since the RM LA250 linear arrived I have had to borrow my 23cm bias-tee for 2m. More later in this blog.

I now have a nice new SHF-Elektronic FSP-144 2m bias-tee for 2m, and so the general purpose one can go back to 23cms.

Anyway, with everything properly wired up on the 23cms this time so I could get going with a bit more confidence. The figures are a bit better. SWR down to 1:1.1, power output up to 53W. This is annoying with a 100W linear.  The root cause seems to be the IC-9700. As I have noted before, power output is only about 4W on 23cms. I am not sure why that is. I need to discover a reason, apart from the obvious possibility that my power meter is faulty. The little LED display on the linear suggest about 50% output, so I have that to go on ...

Buoyed up by all this I went on to the RSGB 23cm contest to give away a few points. I was pleased to work M0XVF and a couple of regulars, but also GM4BYF for a new one. I usually find the Edinburgh area a problem but not this time.

Then a strange quirk of the IC-9700
When I reviewed it I mentioned that the 9700 has two receivers but only installs one sound card in a computer. However, it does have two loudspeakers and two line outputs, leading me to the idea that I could rig up a second audio input and monitor two data frequencies at once.

Well a couple of days ago I was trying to listen on 1296.200 while leaving the other receiver on 2m FT8. The 23cms receiver was set as active and 1296.200 was highlighted as the bottom (sub) VFO. The WSJT-X software was showing the frequency as 1296.200, though of course I was not expecting any FT8 as I was listening to 23cms on the loudspeaker.

Imagine my surprise when MM0CEZ popped up calling CQ apparently on 23cms. Or at least 23cms was the active frequency on the IC-9700. I could hear nothing on the loudspeaker. Curious, I decided to work him and sort out what was happening later. It quickly became clear that the WSJT-X software was controlling the frequency and showing the data contact on 1296.174, but I was working Peter on 2m. Whatever the frequency on the software (23cms), the signal was going out on the secondary frequency (but top on the display), i.e. on 2m.

I thought I should explain to Peter that this was a mistake as he is not exactly DX and he must have wondered what I was up to. He was very good about it and offered not to tell anybody if I felt I needed to keep quiet. After all, I thought, who would admit to working someone on the "wrong band"?

But this does seem to be a "thing". I set about re-creating it on the IC-9700 today. Would you expect this readout to produce a signal on 144MHz?
WSJT-X software showing IC-9700 on 23cms, with 2m contacts being regularly displayed
It might be nice if it was real as I would like to work PA on 23cms.

During this time I was listening on 1296.200 and the IC-9700 display was showing this...
IC-9700 showing a display which does not suggest to me that it is working data on 144MHz.
The S/Po meter on the top (shaded) display shows RF output on 144mHz, whereas the meter reading on the 23cms section with the green mark shows an S-meter reading on 1296.174. The meters at the bottom below the 1296 readout do not relate to that frequency but to 2m data transmission shaded at the top.

There is nothing wrong with this. I think it does not happen if the frequencies are reversed between the top and bottom displays, in which case the data output would be on the same band as the software suggested. I just find it very difficult to comprehend.  I can select and listen to a VFO but yet while my computer is showing the same frequency it is also working stations on a different band as well. That WSJT should show a different frequency from the one it is using does my head in.

An outcome like this is inevitable as the 9700 only has one sound data connection to the radio (active on the top display), but it allows the CAT control to alter either frequency depending on which is selected. So I was able to change the lower highlighted readout from 23cms to 70cms and back again, and the WSJT readout followed, while the RF output continued to come from the USB signal from the computer on 144.174 (despite the computer and the highlighted readout on the 9700 showing 1296.174 and 432.174 respectively).

I usually use the 9700 as a single-band-at-a-time radio. I think, being a bear of small brain, I should stick to that approach.

I said when I first tried the 9700 that it should have been possible to take two separate audio feeds out via two separate sound ports (after all, it has two loudspeakers). The Elad FDM-DUO have several audio and CAT connections. This IC-9700 outcome I find bizarre.

At least Peter saw the funny side of being worked on the "wrong band".

And now for something just plain potty:-
I do not have any 27V operated relays in my relay box. I was offered some 24V ones a few years ago but turned them down as I could not think of a use for them.

It occurred to me that if I had a relay on the 27V DC supply to my 23cm linear it could switch the PTT between the 2m and 23cms linear. When the linear supply was on it would switch the PTT to that, and when unenergised it would connect to the 2m one. No need to plug and unplug the phono plug and lead as I had been doing. And it would be fail-safe as the 2m linear has RF VOX and the 23cm one passes the full 4 watts through. Just turning on the power supply to the 23cms linear would switch everything and no plugs to swap about.

Even better, with both the 2m and 23cms now having their own bias-tees I could supply both pre-amps from my single sequencer. Perfect, and they are now both off when either band is in use, which is good as it means they do not get RF shoved down them on the other band.

The thing is, no 27V relay. And no shops to go to. And even if I was not locked down there would be all that soldering. And I am busy as I have to work people on the wrong band and important stuff like that. And, I want no further expense right now.

Why not use anything lying about? The transfer relay I bought from GM4JJJ's SK clearance sale at the GM Microwave Round Table says "DC to 2.2GHz". OK, DC is a bit less than I had in mind but I can always take it out again if I need it. If I use plugs that is, with a non-solder solution.

I have a few dodgy N-type to SO-239 adapters. And some PL-259 to phono adapters. Drat, only two of each and I need three. Hey, I have an N-type to BNC (I wonder why), and a BNC to phono adapter. I have little need for these adapters as almost everything is now N-type. Why not use them for DC too.

No need to lose sleep over whether the N-type, the PL-259 or the BNC are best at .... 0hz.

And finally, the transfer relay had a 4 pin plastic plug which I have nothing to socket to it (as they said in the 1960s). I cut that off and added two banana plugs. Not that I like banana plugs but they have their uses. In this case to stick into the DC connection posts on the 23cms linear.
Transfer relay and the assortment of pluggery required.
This must be one of the maddest bits of construction I have done. Well, not construction, more assembly. Does it look terrible? Yes. Does it work? Yes.

The elegant way to do this might have been to buy a 27V relay, which at this moment seems a bit mad. The way I have done it allows the valuable transfer relay to be removed at any stage. I could STAY HOME as instructed. And what was I going to do with those adapters anyway?

The even more elegant way is to build a single board computer to read the Icom CI-V line and switch the PTT that way. Don't worry, I am working on that one.

EDIT - More on the IC-9700 in the next posting here

73

Jim
GM4FVM

Thursday, 9 April 2020

Lots breaking down and a deep sense of dread.

I was going to start this posting with an appreciation of Catherine Catherwood, our Chief Medical Officer. Not now, as she has lost her job after breaking her own rules.

The point being that I usually only trust ideas and numbers and science. I generally do not trust people. People who want to convince me have to produce facts, rather than just claiming to be right. We all know who does that type of thing, and we do not trust him.

When I need advice I turn to an expert.

More of coronavirus later.
========================================
This is the time of year for Es to get going, and it has not disappointed - briefly. Things are also doing well on the meteor scatter front, though tropo has not been quite as good as one might have hoped.

There was some early action on 24 March. The earlier tropo which had brought me OZ on 23cms did very little more. Despite the high pressure there was nobody to work. For several days I could call CQ and see my pin in the 2m PSK reporter map at various OZ locations, but having worked all of those there was nobody to talk to. The path across the North Sea on 2m tropo was open for long periods for three days.

The tropo was better to the West where sadly there are very few stations. Mark, EI3KD, was running a special event station on 2 metres to mark the events of 1920 in County Cork. I could not resist that one. I then asked Mark to move to 70cms, which he did and gave me a new DXCC and new square on 70cms.

Despite this, tropo was a disappointment over a period when pressure was high but the moisture content of the air was not suitable.

24 March seems a bit early for a full scale Es opening on VHF, but that is what happened. On 6 metres I worked 30 stations in 21 squares, 5 countries and two continents.
50MHz contacts at GM4FVM on 24 March 2020
On 4m it was not quite as dramatic but it was still an earlier than usual opening...
70MHz contacts at GM4FVM on 24 March 2020
Since then there have been fairly regular stations popping up on FT8 on 6m. Although I have had QSOs, none of it looks like the Es season has started here in earnest, or not yet.

Meteor scatter has produced a steady stream of contacts on 4m and 6m. I have turned on the 100km markers on this map, with thicker lines for 500km.
VHF meteor scatter contacts at GM4FVM, 24 March to 10 April 2020
The most distant contact with Jurek, SP9HWY, at over 1500km was a lengthy affair as it so often is outside a specific shower period. I am looking forward to the Lyrids peak around 22 April when I hope I might make some progress on 10m too. Mind you, if the Es season is underway then 10m might be pretty crowded.
==================================
Yes, lots of things are breaking down, not least of all me.

On the day our local dentists went into lockdown my largest filling fell out. I was "triaged" over the phone and told I was not bad enough to warrant attention so I should rely on temporary fillings for the duration. I had never heard of temporary fillings, so this required a visit to the pharmacist in the next town.

And so began my relationship with a gunky slime somewhere between chewing gum and Isopon on the crud scale. It is not really a filling, but it certainly is temporary. It keeps falling out. I suffer, of course, but in a stoical, level headed way as befits a mature adult who knows it is nobody's fault.

Grrr.

Then my 2m linear, which has already been back to DX Shop four times for repair, failed again ...
The LinearAmp Gemini 2 amplifier failed with a false SWR warning .. again.
For an amplifier to have failed five times in two years is really disappointing. I believe that there is some underlying fault which has never been addressed and I will deal with that in due course.

In the meantime some temporary assistance has arrived in the shape of an RM Italy LA250 linear. How long I can keep this is not clear but it solves the problem for now. The good news is that it is not a Gemini, it came from somewhere else, and it seems to work.

After the Gemini had come back from repair for the fourth time I sold my Microset brick amplifier in the expectation that I did not need it any more. Here is the RM, another brick amplifier, but one which seems to be in a different class. Fortunately I still have the 40 amp power supply and I can borrow the sequencer and bias-tee from 23cms. More on the RM once I have had time to try it, but so far so good.

My CUG mast, which holds up my 4m and 6m dual band beam, failed too. The top pulley broke when I was attempting to raise it. This has also happened before ...
Broken weld on mast pulley at GM4FVM.
The pulley has broken off its mounting plate. It is designed in a way to avoid a catastrophic failure in the sense that if it fails the mast does not fall. However, that design is itself a weakness as it involves a weld under strain which, as can be seen in the photo, is subject to corrosion.

CUG masts have been helpful and say that they have a new design where the pulley is riveted to the back plate. I hope to get one of those soon. The mast jammed half raised, but I was able to work the cable through the hole without the pulley and gradually lower it. It is now down and under its own weight, with the lifting cable slack. Possibly the cable was damaged during that operation, we will need to see, but nothing terrible happened. It is just stuck down now.

Now I have to stress that none of this matters much in the great scheme of things. The world is in the grip of a major crisis and my tooth problems, and even my tripped linear and broken pulley, are nothing in this. Some people have lost their jobs, others are at home on reduced pay, and still more alarming, many are in hospital fighting for their lives. Many have already passed away, and even the grieving have their problems as we know here, as funerals are disrupted.

My issues are not significant. However, this is a radio blog and not a corona virus blog. My duty is to carry on and spout my nonsense. I must do my bit. I even keep trying with KST Chat, even though I find it terribly tedious. I have had good chat with great people, but having it on for long periods locks me into a strange inability to act.

I think KST is warning me about the dangers of radio torpor. An induced state of inactivity, in this case induced by the radio. Doing radio because there is little else to do sets it off. Sitting here starting at screens, imagining there is something useful to do, when there isn't. Sometimes, you just need to get up and do something else, limited though that might be just now.

My general state of dread does not come from the threat I am under from this virus. I have been in danger before, as we have touched on here. There have been times for me, as for most of us, when I have been under threat. Usually this hardly gave me time to think. Either it was over and clearing up was needed, or I had already been knocked unconscious - or delirious - by then. Anyway, danger came as a shock, and it was over pretty quickly.

What is happening now is not an acute state, it is chronic. We do not know when it will end. Looking back, wars and so forth seem terrible in the sense that they lasted for four years, or five years, or whatever. We forget that to those present at the time they did not know when it would end. Just as we now do not know when the present emergency will end.

I feel a temptation to think that sitting in front of the radio is an end in itself. But the radio is a cruel mistress as I have noted before. Just sitting here does not dispel the feelings of dread, it increases them. Sometimes I just have to turn it off and go and clear out the garage. Surprisingly, there are lots of antenna bits out there which I must sort out.

Do something constructive Jim. Do not become a total misery (a partial misery is bad enough). Tidy up. Fix things. Made a new plan, Stan (ooops, not a good comparison).

Radio is a hobby. It is not an excuse to hide away. That way lies the sense of dread.

Spring is here and there is plenty to do.

Just do it.

And keep washing your hands.

And speak 2m from the microphone, just in case.

73

Jim
GM4FVM