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Building A ’37-Style ‘RK-39’ Crystal Power Oscillator
1 July 2019 | by 
When I completed my ‘Jones 6L6 Push-Pull Oscillator’ project in the spring, I made a start on a new ‘spring-summer radio project’ which was to be based on some 1937 RK-39 tubes that had been gathering dust here for many years.
With an unusually sunny and warm spring, I soon found that my radio-bench time was being hi-jacked with a lot of outside yard work and getting all of next winter’s firewood split and stacked away before the really hot weather arrived.
I found myself working on the project in tiny bites, sometimes not making any progress at all during the passage of a week. Headway was also tempered by the fact that I’ll often deliberate for several days over the placement of a single component or the selection of one component over another. I find this slow pace and decision ‘pondering’ during the design phase of any project to be most enjoyable as it gets my old brain working more than normal, on things that really interest me.
I’m happy to report that my latest project is now complete and fully operational and ready for operation!
As usual, I have written and published a web page fully describing the project and some of the background details of the building process.
My ‘Building A ‘37-Style ‘RK-39’ Crystal Power-Oscillator' page can be found here.
Hopefully we can have a CW QSO with it in the near future!
3 Responses to “Building A ’37-Style ‘RK-39’ Crystal Power Oscillator”
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WOW!! That is a beautiful job. I would love to build one. Where can I get the tube??
Paul, K5HKX
Thanks Paul. I’ve noticed in the past that they could be found at many of the online tube dealers.
This is certainly up my street !!! This was exactly what I made in the early 1960s from the ARRL handbook—-worked right of the bat into a Windom wire antenna.
My dad, the original VU2BK ( 1946–2004 ) used a single 1625 in the final modulated by a pair of 6L6s & with dipole antennas–worked the world–between the 1940s & late 1960s–those were the days that money can’t buy ! I still play around with WW2 surplus which we collected over the years & its all in working condx —-amazing what quality stuff was produced–knock spots out of some of the new fangled electronics–specially as far as reliability goes.
Thanks Steve for keeping the old–still alive—we are a fast vanishing breed !