Heathkit HG-10 Mod?

[n1uvi]

I recently acquired a Heath kit HG-10 VFO
The unit works very well so I'm not going to fix it, but a curious thing,
the 6CH8 has been changed out for a 6CB6 and a 6C4 has been added to the circuit next to
the 6CB6. Anyone have an idea what might be going on inside my HG-10??

The 6C4 looks like an oscillator circuit. and the 6CB6 a buffer,  I assume this mod might provide more drive, perhaps
for use with a different rig other than a DX-60 ? Has anyone seen this mod in a HG-10 before ??

[WD5JKO]

  My guess is that the 6CH8 needed replacement, and being an oddball, the OM just replaced it with the 6cB6 and 6c4 that might have been in his junk box. The popular tubes 6U8/6GH8/6EA8/6MU8 all have a different base.

  If the conversion was done well, then just enjoy the HG-10. I always thought the output was kind of low compared to the VF-1. Maybe that was part of the reasoning to make tube changes. Is the circuitry the same as before?

Jim
WD5JKO

[W3RSW]

Similarly, I solid stated the Osc. And follower of an HG10B with a solid state fet lash up in a socket matching plug.  Traded it to Ron, wa3wbc, some years ago. I might be able to find the circuit drawing. Ran 13.8 Vdc to Vfo side of the dropping resistor I think. It 's been awhile.  Worked well and I gave him the whole works.  Ron, you still have it?

I found my old sketch. Used a 2n3823 fet to tube pins  2,6 & 7, and a common hf NPN to tube pins 1,8 & 9.  Only other components are two resistors, a 10k bias resistor from tube pin 5 to 8' and a 470 ohm emitter R from tube pin 1 to 5.

Tube Pin 2' fet drain.
             7' gate.
             6 source

Pin 9' collector of NPN follower
     8 base
     1' emitter.

All above mounted on 9 pin tube plug.  Shield of fet goes to ube pin 5' of course.