Monday, 14 May 2018

Back from a trip, Deep Search and review of small boxes.

I am back from one of my jaunts. As usual it was a rail journey. Strikes on the French railway system put me off my planned route, so it had to be closer to home. It is my belief that you cannot appreciate the world if you do not know your own country so it was time to take a week off and visit The Scottish Highlands.

At this point I usually show a shot of me standing in front of a sign taken in South East Italy, or Belgium, or some similar far-flung place. However, the two shots of me proudly standing below the sign "Welcome to Wick" are both horribly out of focus. D'oh. So I will just have to rely on a photo taken on my phone out the train window ...
Lough Awe captured from the window of the Glasgow to Oban train
OK, I took better photos than this, but it seems to capture the moment better than the others. With trees flashing past as we sped along there was little I can do about the composition.

Having visited Oban, and Mallaig on the West Coast, plus Thurso, and Wick in the "Far North", all in short order, staying in Crianlarich and Dingwall along the way, I can confirm that the Highlands are high. I even took the hand portable and heard ... nothing.
Back here and I received an email from Joe, K1JT. Joe makes two good points about Deep Search. Some of you may recall my long and rambling posting on the subject here.

Firstly Joe has explained that most JT65 EME QSOs do not rely on Deep Search. "The fraction of QSOs (and decodes) that require DS is small for nearly all stations -- and certainly for those qualifying for, say, DXCC. Careful operators use DS to make QSOs faster when signals are marginal, because subsequent messages (after a full decode) are less likely to require repeats". That certainly agrees with my limited experience.

Joe also goes on to make another interesting point - "Recent versions of WSJT-X offer "a priori" (AP) decoding for the modes QRA64, JT65, and FT8.  This feature makes no use of an accumulated callsign database; instead, it makes use of information accumulated during a QSO.  It's very powerful, and works well; it's described in somewhat more detail in the WSJT-X User Guide"

Yes, though I have mentioned here before that not everybody reads the WSJT-X User Guide. They should.

Joe's efforts on behalf of amateurs have brought us very important extra resources for our research. In particular my knowledge of propagation has been vastly helped first by WSJT modes and then those brought together in the WSJT-X suite. I have passed along my thanks for his efforts.
It was nice to have a 2 metre QSO with Jeremy, M0XVF, yesterday. We have broadly similar stations but the terrain between us has always made the 133km path between us marginal. This was my first SSB contact on my revised 2m set-up, and so my first with my low noise amplifier. As it turned out, Jeremy has also installed an LNA and a sequencer. The result was that we had an easy contact peaking above S9 at times.

That little box on my mast is proving it's worth.
Several readers were somewhat surprised to hear that I had bought a small transverter for 70MHz portable use. It isn't really a quality item but it works. When I bought it I had a dim recollection that somewhere in the "general radio bits" box (an Ikea children's toy box re-purposed for this use) was a small box marked by me "70MHz bandpass filter ex-PMR, 10W max".
"Bandpass filter" plus 20 pence piece for scale
I cannot recall now where this came from. I will need to test it and make sure it is indeed bang on 70MHz, as if it came from a Low Band PMR radio it might need some tweaking. Still, I have a larger box with the right sockets to put it in and it should be just what I need to clean up the Ukrainian transverter's output.

I usually remember what is in the bits boxes because I often have to trawl through all of them looking for something which should be in "Computer Bags" box (yes, some of it is bagged and tagged within a box!) but turns out to be mis-filed in "Microphones" (where all the mics are loose in the box). But that is where the memory usually stops - where it came from and how I got it is often lost in the mists of time. But at some stage I must have thought this trifle was worth keeping for some unknown future project.
Speaking of transverters, the big brother box ME2HT on 2 metres now has a temperature controlled fan on top and a temperature sensing probe inside it.

The PA module is fine, but the mixer box starts with ambient at switch on and climbs relentlessly on receive from 20 to well over 30C. Then it wobbles all over the place. A bit of transmitting takes it beyond 35C at which point I feel the need of the fan.

The sensor turns on the fan at 30C or off at 29C. Net result is that the normal range of temperature fluctuation is now down to 2 degrees.

It's still a lash-up. To get the fan blowing on the right module I have fitted the top panel back to front. If I decide I need to fit it there permanently I will need to turn the panel back and drill ventilation holes through it. I'll try putting the top panel back and blowing the air from the back. Never drill holes if you don't really need to.

I am also toying with the idea of a small heatsink on the mixer module box. As that would still be inside the case I would still need the fan.

The benefit now is that the frequency quoted on FT8 is the same after I have completed a QSO as it was before. It is only a tiny benefit, but I would still rather have it.
Another small box useful during various tests has been my rarely used Trimble Thunderbolt GPS frequency standard. Once locked onto GPS it produces 10MHz with high stability, plus copious harmonics right up to 150MHz. It also has a 1 pulse per second output. It has a parallel connection to the computer. The original software has long ceased to work with modern Windows operating systems but "Lady Heather" software by KE5FX works well.
GPS Antenna, Trimble Thunderbolt and PSU
The Trimble can "discipline" the PC clock allowing accurate timing for data modes without an internet connection. I bought it on eBay and it is ex-equipment (the give-away is the sicker marked "used", surely an understatement). This is old tech these days. Much more compact and cheaper GPS standards are available now. It works though.

The PSU is in fact the new generic noisy one supplied by the eBay seller mounted in an ex-PC PSU box.
David, GM4JJJ kindly sent me a Mini-Circuits splitter for the receive path for my transverters.
Top - Rx Splitter, Bottom - FCD, Right - Fan Controller
Here it is linked to the Fun Cube Dongle, which can provide a panoramic view of the 2 metre band or, for example, the ability to listen on the SSB calling frequency while working on FT8. During testing with the GPS standard the FCD proved very frequency stable.

Sharing the same space for now is the lashed-up temperature control for the ME2HT fan. I see we are on 29.4C and the fan is running.
I live in the land of little boxes.




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