[Hallicrafters] SR-400A - no output

[Don]

Hello,

Thanks for reading this.

I recently acquired an SR-400A that seems to work ok on receive but
does not producing any real output. There is no indication of ouput or
plate current on the meter (it actually drops a tiny bit when I key the
transmitter).

Here's what I've found so far:

- V11 defective - replaced
- V5 possibly defective - will leave for now since I don't have
  a replacement
- C180 and R110 missing from V18 (driver screen grid) - replaced
  (someone was working on this before me!)
- bias sets ok
- SSB and CW can be heard on a nearby receiver
- in transmit (CW or tune) the following peak-to-peak RF voltages
  were measured on 80 metres with the RF level control set at maximum
  - V11 pin 7 - 2V with V4 removed (het osc only), 8V complex
    waveform with V4 installed
  - V11 pin 9 - 8V
  - V18 pin 2 - 2V
  - V18 pin 6 - 8V
  - antenna jack - 4V
- DC voltages at V11 pin 6: 13
                         7: 0.22
                         8: 231
                         9: 244
- DC voltages at V18 pin 2: -13
                         6: 229
                         8: 213

As you can see, I'm not getting much amplification in the driver
chain although operating voltages appear to be ok. I've tried peaking
L11/L34 but that didn't help. I tried a 6CX8 for V11 (no other spare
6AW8A) but that didn't help either. I don't have a spare 7558 for V18
and don't know of any substitute.

Can anyone give me some advice about what might be the problem?

73, Don