Sunday, 28 October 2018

432MHz Trans-Atlantic EME on 95 watts, OK I was wrong

There seem to be two themes on this blog (apart from "I'm right and everybody else is wrong", but that is what blogs are for). They are

1) our pre-conceived ideas are wrong so we should try this,or

2) my preconceived ideas are wrong and I am a chump myself for not trying sooner.

This posting is rather about the second type.

On 27 October I worked NC1I on 70cms moonbounce. A fluke?
On 28 October I worked NC1I on 70cms moonbounce for a second time.

Here is what I wrote about my plans for 70cms on this blog on 19 July

This is not an Earth-Moon-Earth capable 70cms set-up. Or at least, it isn't designed to be. It is designed to be vastly better than no setup at all. Adequate, not excessive.

Erm. I was wrong about that. Clearly, it is EME capable. Or perhaps "it isn't designed to be" was my wishful thinking/ get-out clause.
432MHz DX Maps on 27 October 2018

OK, lets get this straight. I still think my 70cms set-up should not be EME capable. To review:-

Icom IC-7100, Microset RU432-95 95W linear, 17m of Hyperflex coax, SHF Mini-70 pre-amp, 2m of dodgy RG-213 and a 12 element yagi with a boom length of about 2.5m (part of a dual band antenna).

This is not world class in any way. The IC-7100, admirable as it is, is a mobile rig. I have cut corners - if I had wanted to go for EME I would have bought a 300W linear and a better pre-amp, but the extra cost (£900 !!!) put me off that entirely. I used existing coax which works on 70cm OK but it not earth shattering. I could have reduced the RG-213 to 3/4 or even half its length if I really wanted to - or replaced it entirely. And, lets face it, a 12 element compromise yagi is hardly up to 70cm EME muster.

It is talk like that (the last paragraph) which I criticise others for using as justification for not trying.


Just because it looks difficult is not reason not to try.
As usual, click to enlarge if necessary.

It wasn't a plan, this 70cms EME thing. At least, there was no plan until I heard NC1I. For the past couple of weeks I have been trying aimlessly to get back into 2m EME and failing. Conditions have been poor. Then on 6 October I noticed Bernd, DL7APV, mention on a chat room that he was working on 432. I went to the frequency and heard him so I reported that and he suggested that we try a QSO the next day. It didn't work. Back to square one.

Bernd has what I would call a "Super Station". 128 x 11 elements. That is pretty big, and it is able to elevate, which puts my 12 elements fixed horizontal pretty much into the shade. Why was I not able to work him on 7 October? After a bit of pondering it dawned on me that my antenna is best near to my moonset when the moon is close to my horizon, and at that point Bernd has passed moonset and cannot see the moon (at least for now). If I could elevate my antenna I would be in with a chance. Or I need to try with somebody who is still seeing the moon at the moment when my antenna is working at its best.
DL7APV's 432MHz antenna ...
My immediate reaction to seeing a 33dBD gain antenna is to run away and hide. My antenna has about 12dBD gain. However, I knew I needed to stifle that feeling. The two figures add together, it isn't a competition. Anyway I did not work him, though he said that there was a contest on 27 and 28 October and he would be on for that.

Come 27 October if I had any hope it was of, maybe, working Bernd.  The same problem arose - as I do not have an elevating antenna he was weak and had dropped out by the time ground gain had started to make my signals to the moon stronger.

As it happened my usual EME chat room was off the air. I decided to call CQ. I was using Live CQ to keep an eye on what was happening and I picked what seemed to be a clear frequency. By another chance I was 1kHz away from NC1I who was clear as a bell. This is a bit of a dream of mine on EME - stumbling across someone I can immediately hear. It isn't so unexpected; on looking up NC1I  on it turns out that he has a Super Station and runs 1.5kW, or at least he can run that much.

So I thought it out. If he has 1.5kW and I have 95W, that is going to give him say 13dB advantage over me. I can hear stations down to, say, -26dB so he might hear me if I heard him at -13dB. At the start he was -16dB. At one stage I went out and raised my antenna height as I feared that the moon would disappear behind the roof ridge, but it turned out that raising it took about 6dB off the signal - it was better lower down. Ground gain and height advantages produce funny effects and my antenna height is not that important when it comes to the moon. Of course, I still thought it might be. So the plan was to keep the antenna as low as I could and stick it out until the moon fell low enough towards the horizon for ground gain to give me a chance of working NC1I.

I started calling NC1I at 08:24. He finally heard me at 09:25. I was calling for an hour and during that time I had all sorts of doubts, in addition to the antenna height issue above. Doubts about antenna direction and whether this contact was possible at all or not. I had many doubts about Doppler effect and whether I had factored it in properly. Then, as the moon fell below 4 degrees (and all the other European stations had lost the moon below their horizon) NC1I's signal started to climb up each segment -13, -12, -08, -04 ... so it was easy to see that ground gain was coming to my aid. Also. my antenna was beginning to function better as the moon started to get closer to the horizontal angle at which the boom is fixed.

When I called at 09:24 I knew immediately as soon as NC1I replied that he had heard me. Even though it took a minute longer to receive the signal and decode it, he must have clicked on my callsign. His frequency moved about 150hz, the amount I had miscalculated the Doppler effect. He must have seen me. And then ... well it just went like a normal QSO. Nothing special about my first trans-Atlantic EME contact.

After the contact he was calling CQ and within fifteen minutes he had disappeared entirely. Moonset had arrived.

Just to prove that it was not a fluke I tried again the next day
This time I left it until the moon was lower - under 3 degrees elevation. I was risking moonset behind the hills. The result was the same though.

I know that logic comes in here - if I hear a station at -15dB and he has a 13dB advantage over me on transmit, then he is likely to hear me at -28dB. Add to that the fact that his receive station might have a better pre-amp and receiver than I have (almost a certainty). Thus he WILL hear me. The EME path is usually steady and I bet he lives somewhere which is electrically quiet (like on a ranch!). Still, I never really expected him to reply both times.

As for the distance (5133km on six figure locators) ??? Well, logic also tells me that if I can reach the moon it hardly matters where on the world my contact is. With an indicative path distance of 752,034km on 27th (a mere 747,302km the next day) it matters little which of us is where on the Earth. Still, working round Europe has seemed a lot easier than reaching the US on 2m. On 70cms my lower power is more or less balanced by more antenna gain so my ERP is much the same, so why am I surprised to do it on 70cms first?

I suppose these 70cm figures give a clue to my pessimism built on years of ignorance

2012 NIL
2013 1 QSO dx 92km (GM)
2014 NIL
2015 1 QSO dx 30km (GM)
2016 1 QSO dx 5km (GM)
2017 1 QSO dx 82km (G !!!)
2018 47 QSOs, 8 DXCC, 2 continents, dx 5133km

Lessons to learn? I am often wrong. I can even believe my own negative script. 95W and 12 elements did do it and I suppose if I had done a careful budget I could have worked that out in advance. Still, my job was to make my tiny signal reach him, which involved sticking at it until the ground gain kicked in, not raising the antenna too high, paying close heed to the moon's movements and not allowing my doubts to overwhelm me.

Here I go again. "I am surprised by those two contacts"

I should have tried this ages ago.



Tuesday, 23 October 2018

Galashiels Rally and how you should spend your money on VHF

Last weekend I visited to Galashiels rally. I should have taken a photo but it never occurred to me. Anyway there were plenty of people there and various trade stands. I bought a solder sucker (90p), a switched mains plug (£1.60), two fixings for wire antennas (50p) and a rather flash loud speaker for £6.00. This was all swamped by the fuel to get there and back, which I estimate at £10.00, plus an hour's drive there and another hour back. You see, I compare all costs and all benefits.

"He is mean".

It was worth it though to meet various people, including a couple of hams who I have worked before but not met. I enjoyed a chat with Dick GM4PPT who is a stalwart of VHF operation, and Robin, GM7PKT, who I have contacted quite a few times on FT8 on the 144MHz band. What both these amateurs have in common is that the paths between us are very difficult due to the mountainous terrain. So it was good to have the time to chat.

Robin's experiences with FT8 are very like mine. In fact the mountains which surround him are much taller than the hills I have to deal with. Despite this he is having success with FT8. This, and comments on this blog, all make me ponder about the success we have been having with FT8. I was a regular user of JT65 and JT9 before FT8 and somehow I never seemed to do as well with those modes, The facts though are that FT8 is slightly less sensitive than those modes. I suspect that a lot of it is due to the greater take-up of FT8 on VHF.

Also at the rally were a lot of second hand radios. There were the usual rather ancient VHF rigs, but there was also a rather neat looking Icon IC-7100, the very rig I was claiming is quite good value at £700. There it was at £550. And they didn't sell it during the rally so I asked how to buy it afterwards just in case.

At the same time I met another amateur who had brought a year old 2m and 70cm radio which he was offering for sale at £35 and eventually he took £33 for it. He then tried to buy a 40 year old 2m FDK for £25. Here he was bringing a perfectly good modern radio and trying to upgrade to an ancient one. He admitted to me that the FDK was very large and would probably not fit in his car. I asked him why he would make a swop like that and he said "nostalgia". In the end somebody else bought the FDK from under his nose - no doubt soon to find that it doesn't have CTCSS or 12.5kHz channel spacing and it is pretty deaf anyway.

Thinking a bit more about all this, I have come up with my own theoretical "law of diminishing returns". This is entirely non-scientific and definitely not a law. It is just my theory about how to best spend money. It was prompted by the experiences at Galashiels and also one particular local who has an interesting approach to VHF operation. The guy in question has outdoor HF antennas, and used to be a keen VHF dxer. For VHF now he uses an indoor quarter wave whip on a magnetic mobile base, stuck onto a biscuit tin lid.

I cannot help feeling that running a radio into a quarter wave vertical and using a biscuit tin lid for a "ground plane" is not a really good use of resources. So I have come up with a graph to represent my law of diminishing returns (which, again, isn't a law). The graph shows a better way of gaining returns for your money be showing an alternative red line.

The idea is that if you use an indoor vertical it doesn't matter how much you spend on a better rig it makes little difference. Your money is better spent on ancillaries like masts and antennas, or coax and pre-amps. Well, that is my view.

Of course lots of people have problems putting up large outside antennas (though the biscuit tin lid guy can as he has HF ones), or have planning issues, but it might be worth a try with something simple - more than buying a new radio anyway. Even if you go portable because you cannot get a good antenna up at home the same general rule applies, so long as you can lug the associated gear out to your portable site. It will usually make your station work better than the same investment in a fancy radio.
The GM4FVM VHF cost/benefit graph (aren't results measured in "JIMMYs"?)
 You will probably need to click on this to enlarge it enough to see it.

I am suggesting that after you have got a "new" multimode (by which I mean modern, the second hand IC-7100 at Gala show would do at £550 and save you some dough for antennas), spending more on radios just keeps you nearly flat on the dotted line. You will have diminishing returns in that there still is a return, a better rig is a better rig, but you get less benefit in term of results for the £££ you spend now than on your basic radio. On the other hand, spending on other things (along the red line) brings you steady returns. I have found that spending a £ on the red line brings a considerable result, whereas spending a £ on the dotted line seems to do very little..

Who am I to tell people how to spend their money?

I have no right to suggest all this, but I do believe that you get a lot more return out of improving your station generally rather than improving your radio. Yet at Galashiels nobody was selling yagi antennas, good co-ax or masts (well, there was one old but nice second hand Clarke pump up mast which I looked at for a long time!).

So what is the way I am measuring "results"? Well, based on my experience - locator squares, distance, countries, surprise long distance contacts, learning about propagation, lots of things. I never said my theory was scientific.

Hey, results are measured in units of increased utility (work that one out).

As for my order of things to improve, well that is based on what I see going on around me. A gable end mast is just a pair of T and K brackets attached by expanding masonry bolts into the end wall of a house - fine if you have a masonry end wall, but there are other ways of doing it. If you have a vertical, get it into the clear and as high as you can using a gable end mast. Ideally use something like a half wave which does not need a biscuit tin to ground it. Next thing is a directional antenna, even if it has to be turned by hand. We used to have TV rotators but nobody has made one that passes the CE test so they are not available in Europe at present. Rotators are simple things, just a motor and a gear box and you can usually get them cheap second hand.

Here is s simple example. For a while I used a vertical on 50MHz. I did very well during the sporadic E season. Then I got an HB9CV (the Diamond one) mounted on a simple bracket cadged off a neighbour and supported by 1.5 inch thick-walled alloy tubes. With the vertical I could work Europe; once I had the HB9CV I could work across the Atlantic. It wasn't easy, but it was possible.
Simple, HB9CV, old TV rotator, good enough to work Puerto Rico on 6m.
The step up in results from a vertical to a directional beam, even a simple one, was huge and far greater than any investment in radios or linears could have done. I was very chuffed when I worked across the Atlantic for the first time. That antenna opened the door to meteor scatter and aurora work too. Better antennas are better on receive as well, so they beat linear amplifiers by a mile.

After that, a better antenna - I am not suggesting that your first steps in improving your antenna are likely to be your last. I certainly have tried my first setup and then upgraded in every case (except, so far, 70cms). As you know, none of my current antennas has a boom longer than 3m and that is enough for me. My advice is to pay little attention to the number of elements and more to the length of the boom (the HB9CV being an honourable exception).

It cost a bit, but I found a tilt-over, crank-up, mast to be very valuable - also more valuable than a linear. For VHF use it allowed me to get to twice the height over the ground of the gable end type of fixing. Partly getting a tilt-over is due to me getting older and less about to climb and haul things about up ladders. Also I live in a wild and windy place. Once again a wall-fixed tilt-over mast is enough for me, free standing masts are a step too far here.

Whilst I rank the free-standing mast as being more useful than a small linear, I don't rate big linears anywhere. I do not see the need for full legal output anyway, and I am content with moderate power. After a while barefoot is not enough, but I am happy to look in the magazine at what the contest operators are using and get with about 3dB of majority are using.

Better coax. A lesson we all have to learn one way or the other. It is expensive but it is worth it and in my book worth more than the same amount of money spent on the radio. Coax does not last for ever, and when you need to change it there is a chance to improve it. A mast head pre-amp - the final essential item on my list to a achieve best results, something to bring your receive performance into line with your transmitting ability.

Then, maybe, someday, a better radio. I like better radios, but I am kidding myself if I was to claim that they really get much better results.

I bet I am criticised for saying all this. If it was not for the subsidy the amateur radio magazines receive from equipment sellers advertising really expensive radios then we wouldn't have a radio press. And we all love a nice radio, including me. Yet when I want to buy a £200 mast head pre-amp I had a devil of a job finding somebody to sell me one, whereas I can buy a TS-890 at £3999.95 (carriage extra) - reduced from £4299 - a snip - anywhere.

By all means spend your hard-earned money on a shiny new radio. But please, think about climbing the red line first.

"There he goes again - off on his hobby-horse."

"I bet he buys some fancy radio soon - he is just softening us up."



Sunday, 14 October 2018

My grudging appreciation of the Icom IC-7100

Yes, I know I have promised something more about 1970s VHF, but it is all just too complicated. I am working on it. In the meantime, this ...

I believe that the major Japanese manufacturers are puzzled by the Western habit of buying "mobile" radios and using them as base stations. Why, for instance, when Icom offer us the IC-9100 base station, would anyone want to use the IC-7100 mobile radio from home?

Erm, maybe because the IC-9100 is currently £2799.95 while the IC-7100 is £999.95.

Now of course the IC-9100 is a better radio than the IC-7100. It is better equipped, it has a built in ATU, it will produce 100W on 2m and 75W on 70cms (or at least it claims to, I have no personal experience) compared with the 7100's 50W on 2m and 35W on 70cm. With the 9100 you can add a module for 1296MHz, if you have £623.99 to spare for that.

If you accept that the IC-9100 is better, even though you might wonder if 180% more £££ would bring you exactly 180% more joy, that does not mean that the IC-7100 is easily written off as a base station.
The IC-7100 control box at GM4FVM

I must declare my interest. I have had an IC-7100 here since August 2013. You can look back in this blog and find me moaning about the "clicking" sound on transmit, which I can find but nobody else has ever heard (maybe it is inside my head). You can also find me complaining about the low average output on SSB, which I resolved by using an outboard speech compressor. Apart from that my total list of complaints is NIL.

(EDIT -  here is some of it

Five years is a long time for me to hold on to something which I might have doubts about. That's the thing about the IC-7100, it just does its job. It works. I have never doubted it. OK, along will come the IC-9700 which will I guess make a better VHF  base station than even the IC-9100. But will it cost £999 new?

I noticed a couple of second hand  IC-7100s on eBay. They sell for about £700, or even less. That is quite a bargain. No doubt there are some poor condition ragged ones about, perhaps modified ones too, but mine has had nothing more radical done than to add an N-type socket to the VHF side. Any others like it on sale might be a very handy used radio.

Let's think about it. Rather than comparing it with sets at three times the price, at it's own price, second hand, it is streets ahead of anything else around. The Yaesu FT-857 is an ancient plodder by comparison - it doesn't have IF DSP like the IC-7100.

The 7100 is still in production. You could pay sky high prices (£1000++) for an out of production IC-910, and not get the USB connectivity of the IC-7100. The 7100 just needs to have its USB plugged into the computer with no audio data interface. Sure the IC-910 is better in many ways but the 7100 gives you HF for free.

There are lots of out-of-production VHF radios you could buy second hand for maybe half the cost of the IC-7100. The problem with this is that they are now so old that their performance is below what we have come to expect. Solder joints are failing and capacitors are drying out. The IC-7100 is stable enough for data in that it does not drift significantly. It is probably more sensitive than the old rigs but maybe not quite in the latest transverter league. For £700 you would get solid performance by comparison with older equipment, but it is not quite earth shattering.

The IC-7100 was designed with FM and DStar operation in mind. It has good cooling and an effective fan. This means that it is very happy with high duty cycle work, and data seems to pose it few problems.

There are some nice aspects of using the IC-7100. It has separate PTT outputs for HF and 2m/70cm. This means you can use a linear on 2m and a different one on, say 4m or 6m, and the linears would only come into use when you select the right band. Of course, HF, 4m and 6m are all one one PTT output, and 2m and 70cms are on the other, just like the RF output sockets. I certainly made us of this feature. Also, as the control head is separate I could mount the radio at the point where the 70cms coax enters the shack whilst having the control box on the desk. This saves some lossy coax.

For the European market the IC-7100 comes equipped with 70MHz. This was a bonus for me at the start as I already had a 4m transverter. I planned to stick with the transverter. Within weeks I was using the IC-7100 on 4m exclusively. Later I used the LDG IT-100 automatic ATU with it on HF and that proved very satisfactory. After that it was my 6m rig, then my 2m rig, and now it is my 70cms rig. In that role I can produce a map of what it has done because it is my only 70cms transmitter (apart from FM which I only listen to).
70cms contacts at GM4FVM 30 June to 14 October 2018 (F1BHL/P sadly missed off the bottom of the map)
If this looks modest, it is 70cms and I had my first QSO on 30 June which is three and a half months ago. All of them on the IC-7100 - though lately with a 95w linear. On all bands I have had hundreds of contacts on the IC-7100, from Greece on 70MHz to Canada on 50MHz, to Australia on 28MHz and lots elsewhere too.

There have to be some downsides. My early model came with a fairly poor microphone. The physical design with its sloping display is a bit odd. Spinning the VFO feels rather peculiar as the control head tends to move - it needs the free moving finger cup which the IC7300 has. Some of the logic for switching between meters on the touch screen display seem strange. Some people don't like the monochrome display but it never bothered me.

This is a very personal thing. I borrowed an Icom IC-910 and hated it - the ergonomics appalled me. I do not like the looks of the TS-2000 (but it is discontinued now anyway). The IC-7100 is not a radio I love either. I cannot deny it has served me well. As a new buy at the current price of £999 (and less on the grey market) or about £700 used, it really does compare well with older models in the same market sector (which means the Yaesu FT-857). As for anything older still, I wouldn't consider any of them if I could find a clean used IC-7100. It certainly is not perfect, but it is modern and it works.

In case you think I might throw my IC-7100 out when I do eventually buy a VHF base radio, have no fear. I have plans for using it mobile - goodness, a mobile radio used mobile! Of course, I cannot buy a VHF base station until somebody makes one I would want or could afford, but that is another story.