Elkin 12-tube on ebay

[KG0MN]

I don't think I could afford the tubes for this if is using TV sweep tubes like some of them used to. Plus he is asking $550.00 which doesn't seem that high if it works properly. Anyone know what the output on these are?

Elkin RARE 12 Tube Linear Amp Amplifier | eBay

 

[ExitThirteen]

A 1625 tube is the same as a 6LQ6 for plate dissipation, about 30W per tube. So I'd reckon this would have similar output as a 12 tube D&A Phantom. Approx. 500-600W PEP on a good wattmeter. Note the 4 - 6BQ5's in the upper left corner of the amp, laying horizontal across the transformer, that aren't actually hooked up.


~Cheers~

 

[Shockwave]

The 1625 is a world war two military transmitting tube often forgotten about today. RCA made millions of them for the war effort through the 1940's and 1950's. The ones marked for military service are the best.

Four NOS can be found on eBay right now at this link for $25 shipped: Tubes 1625 One Lot of 4 Usnavy CRC RCA | eBay. The most interesting thing about this Elkin is not that it used 12 old tubes, it's that the circuit uses them in a push-pull RF configuration.

Notice how they are wired in two sets of six? That's not one stage driving the next when you look at the type of tank coil those two banks of tubes feed. This circuit runs cleaner by canceling harmonics and is the only 11 meter tube amp I've ever seen like it. Since it has no driver stage, you can bet these tubes are grid driven too!

I just noticed this Elkin has four voltage regulator tubes mounted off to the side. They could only be there to establish a stable, low impedance power supply for the screens of the final tubes. This amp is grid driven and was built by someone who appeared to know what they were doing.

 

[Shockwave]

Note the 4 - 6BQ5's in the upper left corner of the amp, laying horizontal across the transformer, that aren't actually hooked up.


~Cheers~

Those four tubes would be the screen regulators. Notice they are 7 pin miniature and not 9 pin like 6BQ5. Probably 0A2 or 0B2 tubes. VR tubes only need two wires connected to them since they drop a precise voltage across two elements with no filament inside the tube.

Similar to a big neon light bulb that can support current. They can be wired in series and parallel combinations for added voltage or current.