Showing posts with label ham-radio. Show all posts
Showing posts with label ham-radio. Show all posts

Experimental QRP transmitter by UB5DT, "Radio" magazine, April 1967

"Radio" magazine cover, April issue, 1967
For those of my friends tube radio builders, who asked me about "Soviet novice transmitter", "XUSSR QRP TX" (as it pronounced in telegraph),"something authentic, but not too complex" etc, such a RIG should be a good choice - easy to build and clearly adjustable design, small amount of widespread parts, a lot of potential operational fun (two possible output sockets, changeable configuration, very uncommon CW note, i believe). And, after all - a frumpish bald telephonist on the cover as a genuine sign of Soviet authenticity.

Experimental QRP Transmitter by I. Tsapiv (UB5DT):

This simple two-stage telegraph transmitter has been developed for a QRP experiments on the amateur HF bands.

The rock bound exciter on the 6П3С (6L6-GB) vacuum tube utilizes circuit known as the "Three-point" (or Tritet in common notation). The crystal controls the frequency of oscillation - 3510kc in this case. Signal output is taken from a separate tuned tank circuit L1C4 in the plate circuit of exciter; this tank should be tuned to 3510kc or 7020kc.

The second stage on the 6П7С (6BG6) tube acts as an amplifier or frequency multiplier (doubler or tripler) depends on an inductance of the L2 coil and bias voltage on the signal grid of this tube.
QRP Transmitter
If you would like to use this transmitter on 80m band as well as on 40m with a noticeable lowered power, you have to connect an antenna to the "A1" connector and pull the amplifier tube (6BG6) out from the socket. For the general power output on 7020kc and QRP operations on 14040kc and 21060kc that tube has to be back and antenna switched to the "A2" output connector.
Measured Power:
frequency single stage (6П3С) both stages
3510kc 8 W -
7020kc 3 W 18 W
14040kc - 6...8 W
21060kc - 1,5...2,5 W

Several interesting QSO's  has been obtained using this transmitter in October 1966. For example, UA0MX and K2AGU on 14Mc, and F9MC on 21Mc with a power level as low as 1.7 Watt.

TNT Uncovered - Flea-Power (QRP) Telegraph Transmitter in the Pilot Radio's "Radio Design" magazine, 1930's

Pilot Radio And Tube Corporation, trade mark

I found this article in the Lloyds Dipsy Dumpster - site, where you can find a lot of rare vintage radio articles, manuals and data sheets.

It is remarkable, that "Pilot Radio & Tube Corporation", well known as a manufacturer of the great Super-Wasp receivers, was a publisher of a Ham-Radio literature, handbooks and magazines, as well as many of early radio manufacturing companies. As for me, I like that sort of advertising much more, than modern spam in my mailbox and if it would be possible, it should be a nice choice to make this QRP transmitter using a native Pilot's parts only.

Anyway, when I've read this article, one interesting fact has drawn my attention - I can recognize the TNT when I see a TNT design, but in the text this transmitter has been described as a TPTG.. Moreover, there is a grid capacitor on the assembles view, but with a opposite description below: "condenser is not needed". So, in the article we can see that mysterious moment, when as the chrysalis becomes the butterfly, TPTG transmitter was transformed into a trendy TNT.

USSR HAM-Radio CallBook in 1926

I just found a very interesting paper - a complete list of all transmitting amateur radio stations in 1926 in the USSR, club stations, as well as personal ones. It is remarkable, that the frequencies and power levels of club stations are selected in such a way that ensures reliable traffic between distant regions and Moscow - the farther station from center, the higher its power and shorter its wavelength. And another note - individuals had managed to use different wavelengths, so it was not too easy to contact each other that times.

Simplified Amplification

UB5UN & UT5AA SSB Handbook
There was a Book Of The Books in early 1970's - "Amateur Radio SSB Equipment" by S. Bunimovich (UB5UN) and L. Yailenko (UT5AA). Funny, but this book can be found in a common pirate's shack as well as in an Extra-class (1-st xUSSR category) HAM one. Yes, xUSSR pirates used AM only (mainly?), but this book was a great source of knowledge about tubes, transmitting equipment etc for everyone who been proud to heat The Ether.
There is a huge pile of a very complex things that described so comprehensible in this book, such as Phase Shift SSB Modulators, complete Transmitters, SSB Receiver's features, Dynamic Biasing and much more, but it is too hard work for me to translate all of those great articles and I decided to start with exposition of pair of a Ground Grid Linear Amplifiers - so simple, not so powerful, but namely these amplifiers was most popular in 1970's. Thought, every xUSSR HAM made one of these amplifiers and used one with a great success.
As for me, I did :)