The AM Forum

For those of you trying to avoid getting an energy star rated shack, this is the VHF preamp for you!  It probably draws around 300 watts total between filaments, fan, B+ needs, transformer loss, etc.

For a long time I've had a project in mind, a regen receiver using an 833-A.
Maybe, finally this winter.

I did once build a GG preamp for FM broadcast using a WE 416 I got out of some surplus C-Band telephone gear, it worked great, yeah, prolly pulled 50 watts.

Thanks for the posting.

Reminds me of when I worked for a company that built some of the hardware for the LAMPS anti-submarine warfare system. The sonobouy receivers festooned on the P3 Orion's had a pretty rough RF environment to work in. To operate without being driven non-linear by nearby transmitters they had a 2N3866 transistor, more commonly used as a final amp in 2 meter HT's, as the first RF preamp. It had about 150 ma of standing current running through it, and a heat sink as I recall. Not as hairy as a 2C39, but still pretty stout.

I like it, good front end protection too.

He must have run that into a SCR-522, any other radio would have blown its input stage.

And dont try it ahead of any SS.

Bill, 

I look forward to seeing results and photos from that project.

Are you going to write an ER article on choosing the best transmitting tube for a regen?  :)

About the use of the 2C39A tube also as a low noise receiver amplifier.
The Boonton 230A (later HP230B) uses 3 of these tubes.

In the early days of VFOs, right before WW2, some people tried using transmitting tubes like the 211 as the oscillator tube.  The idea was that a transmitting tube had so much dissipation rating relative to the power of the oscillator circuit, that when running as a low powered oscillator (real VFO, not a one-tube self excited oscillator transmitter), the tube's temperature would not change significantly.

I suspect the results were disappointing, since after the initial warm-up most VFO drift results from rf heating the coil and capacitors in the tuned circuit, not from rising tube temperature. The normal warm-up of a 211 would likely cause much more drift than that of a 6C4.

Solid state VFOs tend to be more stable mainly because the oscillator usually runs at a lower power level than that of a tube type oscillator.

I had one of those. The one I had called for a special version tube with a smaller anode radiator.