Compliments always welcome

I have just received an unexpected email from Michal, a Polish radio amateur, callsign SQ7JZI, who has been monitoring my longwave transmissions recently. He wrote, " Incredible VLF signal to 137KHz, congratulations. What equipment do you use ?"
Of course I had to tell him, and encourage him to radiate his own signal. Then there will be 3 from Poland on the 2190m band.
Signals on this band are rare; still none at all from many of Poland's neighbouring countries. I hope someone from there will one day be able to change that. It would certainly add interest.

Circuits

This evening I have been transmitting on longwave, waiting for a contact partner, but none appeared, although I know that my signal was being received in Nuernberg, Germany, 745 kms away.
While waiting, I realised that until now I had never placed on my blog a circuit diagram for any of my construction projects; and yet there might be some visitors who would like to copy some of my designs.
Although the picture can be enlarged by clicking on it, whether I do this again still depends on the clarity.
Anyway, I try it at least once, with the circuit schematic of my GS31B 50MHz amplifier from 4 years ago. ( see also 25th January 2010 ).

My Russian toys

Though not dolls, there is nevertheless a progressive increase in size.
They are Russian made high power triode tubes, ( thermionic vacuum tubes, valves ), ideal for use in VHF/UHF transmitter power amplifiers, and significantly cheaper than western alternatives.
So, from L - R, the ones I have are type GI46B, GS31B and GS35B; in each case the suffix 'B' denotes tube variant suitable for forced air cooling, with or without the finned anode cooler. ( An 'A' here would mean water-cooled ).
The GS31B is a spare in case the one in my 50MHz amplifier, ( see post of 25th Jan, 7.23pm ), fails one day.
I am currently building an amplifier for 144MHz using the GS35B.
I haven't decided what to use the GI46B for yet. If I can obtain a second one, then making an amplifier for 432MHz using both tubes with their outputs combined would be an interesting construction project.

International Space Station

I was sitting in my radio room while wondering what to do next when I saw a radio contact confirmation card on the wall. Perhaps because it has been there a long time, I rarely notice it. As it may be of interest to the many visitors to my blog, I have put it here. The card shows the International Space Station, ISS, of course, and was sent to me as a memento of a conversation I had with Bill McArthur, the Mission 11 (?) commander, as the ISS passed over on 27th November 2005 at 11.00am.
I guess the ISS has grown in size since then !

Frequency synthesiser

Having decided on all the additional functions I want, ( band change, tuning step selection, PTT and output filter ), and the switches and connections that will be needed, during the last few days I have progressed further with the frequency synthesiser project from the experimental and development stage, ( see 25th January ), to the first, ( boxed ), prototype. The green, back-lit, dot-matrix liquid crystal display gives a particularly pleasing appearance. The source code still needs some refining. The inset shows new code being uploaded via the 'in-circuit serial programming' interface, ICSP.

Weather bad, longwave good

Tonight it is snowing again. The large coil is outside and connected to my antenna, but has little protection from precipitation. Although the weather is poor, radio propagation conditions on longwave tonight have been good. I have just completed a contact with Gerhard in Austria. The screen shot shows him calling me at the start. The other horizontal lines are sidebands from the LORAN-C navigational system on 100KHz. There are LORAN-C sites in coastal regions of northern Europe. We have to put up with its interference until the system is supersceded by GPS. The sound it makes is like a steam locomotive travelling at 100mph. To our advantage, however, these 'lines' give a useful indication of propagation conditions on 136KHz, and were strong and clear tonight; hence the possibility for my contact with Gerhard.
My signal was also picked up 745 kms away in Nuernberg, Germany !

Home-made PCBs

I made a printed circuit board, (PCB), today as part of the same construction project reported on 25th January. The quality achieved when making ones own boards in the kitchen at home can be remarkably high. I use silkscreen printing and photographic methods of production depending on the nature of the board. If I need a copper ground plane, (as in this case today), in order to equalise earth currents because radio-frequency signals will be present, I adopt the photographic method. If there are only to be tracks present, then the silkscreen printing method is quicker.
The picture shows the silkscreen layer, (top), for component locations, then the track pattern, (mid), and finally the etched board ready for drilling and populating. Click on the picture to enlarge it.

Modifying PC PSUs - finishing off

Recently my electronics workshop in the cellar has become just warm enough to visit to complete the modifications. Since the posting on 26th January, I have chosen to use 30 Amp Anderson Powerpole connectors for the red/black 12V output terminals; fitting a LED 'power-on' indicator and non-slip rubber feet underneath completes the work.
( Thanks Richard for donating the original. )