Sunday, 18 June 2017

A dual-band antenna, 70MHz JT65, and classic rigs

These are the days of the Es season when I change gear. I go into cruise mode.

The "new-ness" of it all has passed. I have no need to work the same station today as I worked yesterday. Others do have this need for some reason. Mostly I sit and watch them all working each other, and I wonder what they have learned since the day before.

Personally, I prefer to look for new squares and new countries. I am of course happy to answer calls if I call CQ, but then I do not spend all day calling CQ. I leave it to others to call CQ continuously. And they do that duty rather well.

True, I have had a few successes in the past few days. IK2MMB (JN45 1382km) was a nice contact on 2m on 16 June. HA/SP7VC (KN17 1866) was a new square on 4m. I really appreciate people activating these rare squares.

It was not so good with an activation from the Nordic VHF meeting in Sweden. The 4m meteor scatter station would have been a new DXCC as well as a new square but it was not to be. I heard them many times, but could not get through. I tried to email them as they did not seem to be sticking to the split they were alleged to be working, but I only got a reply after it was over, and it said that I was too late. Clearly this team put a lot of effort into this activation but sadly I could not work them. Again, for another year. I said that last year.

Also nice have been some contacts on 70MHz JT65. There is no frequency allocated for JT65 on 4m. In fact, the WSJT-X software is supplied with entirely the WRONG preset. It defaults to the WSPR frequency, and every month or two I see people who use this setting this being scolded on the cluster.

Anyway, several people have commented about 4m and I decided to try 70.176. This is not ideal as it falls inside the precious German allocation, but where else to go? I then worked G0XVF and G0MJI, both of whom have been pressing for some JT65 action. Then I was really surprised to work GM4ZMK, also on 4m JT65. This was followed eventually by DL5MCG (JN48 1113km), my first "DX" JT65 contact on 4m. It is not for me to say that 70.176 is the "right" frequency, but I hope that it (or some other one) becomes standardised.

So why do I want to see JT65 on 4m? For the same reason I like it on VHF in general. There seems to be a general lack of interest in data modes amongst some VHF operators. However, JT65 is not just a replacement for SSB or CW, it offers its own special attributes. It is particularly suited to long distance DX working. It was designed for Earth-Moon-Earth use and that is a similar steady low strength situation.

Lately we have had many stations worked from Europe on 6m, as far away as China, Japan and Korea. This, it is suggested, is "Short Path Summer Solstice Propagation" (SPSSP). How this differs from multi-hop Es is subject to discussion. For example, is the frequent path from here to the Caribbean, or the United States or even South America at this time, also SPSSP, or what? Well, in any case, JT65 is brilliant for it. CW also works, SSB is tricky and that is it.

As I write this I am still struck by a station in China who was working streams of Southern European stations on 6m, and who then posted that he was hearing the Angus beacon on 4m well over S9. The Angus beacon in China! Then the posting appeared that Haiti is now available on 4m too (is this official?) plus last year's information that at least one other South American country (was it Colombia?) is also active.

First of all - the 4m Angus beacon was heard in China when there was no 6m path for me. How often would 4m paths be available, perhaps on different trajectories, when 6m is open? How did we not know about SPSSP before a few years ago (i.e. not before JT65)? What can we do with it? Does it extend to 4m regularly, if at all?

I saw an interesing post on a Belgian amateur site. It said that this is a "scientific hobby and not just a communication hobby. In other words, it is not CB". How true. Here we have a genuine scientific discovery in SPSSP, and that beats working the same station on successive days. Well, it does for me anyway.
I have been trying to reduce the number of poles here. Also, my cobbled together ex-dual band beam was in use on 6m, and something had to be done before it fell down in the wind. I seem to have resolved all this, though I now have another dual-band antenna, which was not in the plan to start with. Or two antennas mounted at the same height working on two different bands.

The replacement for the old 6m beam is commercial. Making it into a dual band beam is entirely an FVM invention. It is a Sirio SY50-3. This is the three element version. It is rather well made and should survive the weather here well.

The elements appear to be aluminium tubes with castings for the attachments. The attachments hold the elements using worm screws tightened with an Allen Key (Hex Key). The attachments themselves are pre-fixed to the boom at preset lengths. They are lightweight castings and look very impressive.
Attachment for the reflector on the Sirio SY50-3

The antenna is otherwise conventional, with the dimensions you might expect. The coupling to the coax is via a gamma match, and the recommended tuning settings seemed to work with a low SWR.

I am impressed by the construction. Whilst light weight, it looks sturdy. It took about 90 minutes to build (during which I built it back to front - in some ways I am still like a beginner).

The irony is that I am now about to replace the co-ax to that antenna because it was ruined by water ingress - through a Sirio vertical. Sirio antennas have generally served me well, but their 4m J-pole CX 4-68 seems to have a problem. I was warned that it lets in water, so I double wrapped the joints with self-amalgamating tape. Despite this, it filled with water, which seeped past the PL-259 and into the co-ax. The CX4-68 is a great antenna, but it has this basic flaw.

So, with the new Sirio beam up, and my Sandpiper ring base 5/8th 4m vertical above, where am I to put a 2m vertical? Why do I need a 2m vertical? Good question.

I then took my trusty old dipole, which has been in use here for many years. Over the years it has been altered to serve for 2m, 4m and 6m, horizontal and vertical, fixed and rotatable, portable ... everything. Now it is formed as a 2m dipole and fixed vertically between the driven element and the director of the Sirio 50MHz beam.
Sirio 6m SY50-3, with 2m vertical dipole and Sandpiper 4m 5/8ths vertical
This is a bit difficult to photograph. It is hard to see that the 2m antenna is vertically polarised, and the 6m horizontal. And the stand-off for the 2m antenna is exactly beside the boom on the 6m beam in the horizontal plane, but it never looks like that from the ground.
In reality, the 2m support is beside the 6m boom.
I had done this before of course. You may recall this 2m antenna briefly beside the 4m beam in the past. It may not last much longer this time. It is a lash-up. Any compromise will affect both the 6m beam and the 2m vertical. For now though it is working fine.
"Classic" rigs have quite a following.

Myself, I can do without.

There may have been a "golden era" of amateur radio equipment. It started with commercial SSB transmitters and transceivers. Early Collins, Drake and KW rigs are in this category. Then a series of hybrid transistor/valve rigs from Yaesu and Trio/Kenwood.

However, I would say that rigs from the all-transistor era which followed are not worth resurrecting. Early transistorised rigs have output transistors which are prone to failure (they were dodgy at the time), failing switches, filters going out of alignment, capacitors leaking, resistors cooking ... in fact they are something of a liability. The older ones are similar, but worth fixing thanks to the (hard to find) valves.

Then we had the arrival of surface mount technology at which stage nothing is easily repairable. Unique displays fail and replacements are not available. The chips were discontinued years ago. The switches fall apart. Everything is tiny.

Try to put these rigs on the air and you find the problems. From my point of view drift is the big drawback. These things were designed before we had JT65 and WSPR. They cannot cope. For FM they often have the wrong spacing, the wrong deviation, no CTCSS, noisy synthesisers ...

Are there no classic rigs in the modern era? Possibly the FT-847, a rig I have never owned.

I can see the idea of buying an old VHF rig. They used to be single band, and often they were much loved in their day. There is no such thing as a VHF rig now, so the old ones appeal. In general, they do not fit into the modern shack. For all the reasons above, old rigs are a problem best avoided. The VHF ones seem to be worse as technology has advanced.

They say you appreciate your own old rigs. So it is personal. Yes, my Trio JR-599 would be a classic if I still had it. Or my FT-101s. Or the TS-530 I never had. I recall the KW2000E from the radio club at the Belfast YMCA radio club, and the FT-200 in the Queen's University club. Do I want these now? No thanks.

Key factors for me now - panoramic displays, DSP filtering, ideally SDR architecture, USB digital in/out for data modes, very good frequency stability - all things unheard of in the "good ole days".

So why do these old tubs attract so much interest? Well, the shops like taking them in as trade-ins ("part exchange") and then selling them on. Magazine articles praise them but ignore the problems. Everybody is making money selling them and writing about them, so of course they say they are great. Yes, put one on your shelf. But don't expect it to be much use these days. Turn it on and take a photo with the lights on (if you can get them to work). Then turn it off and admire it. They look great. That's about it in my book.

I can see that true pre-SMD classics are great restoration projects. The repair then is the object, rather than trying to suggest that the restored rig is comparable to anything we might use today.

If there is a classic rig worth having, it was made before 1980 in my view. After that they are just bundles of heartbreak.

They do look nice though. If I wanted to live in a radio museum I would not be working much. Luckily, I want things to work as well, so that is OK by me.

There is room in this hobby for all sorts. Sure, put your old rig on the air. It is not for me though. I will watch you drift past my waterfall. If you can get your receiver to stay put you will see my truthful reply "no decode". Sorry.




  1. Hey!
    It was an experiment!

  2. Hi Dale.
    I had to sit and think about what you mean by that. I was not getting at you!
    I would get at the dealers who sell really old gear as if it was comparable to new stuff. Sometimes for more money than new stuff. And I am against magazines for touting old gear as "classic" when in reality it is fraught with problems.
    I see a dealer today asking £700 for a 20 years old radio which is rightly reviewed on eham as being "old gold not shining any more". An FT-450 would do better for less money.
    Keep up the good work.

  3. Wounded I was. Wounded to the core!

    Naw I never thought you were getting at me, but the dates aligned.
    You are of course correct however have you ever heard of retro computing?
    It's a thing.

    Part nostalgia and part the challenge of pointlessly getting and old bit of kit to do something modern.
    ZX Spectrum Twitter client or building Wi-Fi modems for BBC Micros.

    Totally pointless. I got into it about ten years ago. In that time the cottage industry around it has exploded. Mostly fuelled by the Pi and Arduino.

    It's interesting. Check it out if you've not seen it.

  4. Dale.
    I understand. I had a ZX81 and I still have the power supply (D'oh). I have such basic (more modern) things as a Psion and at least three Palms, which still work.
    I remember the first time I actually got the ZX81 to draw a box, pixel by pixel.
    GM4XXL has presented me with a Mark 1 Pi to play with.
    I know this is not retro, but it is interesting.
    I am not anti-vintage. I am anti selling rigs for large sums on which the solder has corroded away (not that it was good solder even when new). 70s rigs can be good as far as they go, but 80s and 90s ones are very badly built. Or so I feel. There may be one or two exceptions, and of course any that still work are already qualified as stayers and are likely to last even longer. So maybe the odd portable Yaesu is OK!
    I hope to speak soon.
    73 Jim GM4FVM
    ? Wi-fi on an BBC Micro ? Now that would have got them thinking way back when?