HQ-170 AVC "pulls" freq?

[Doug Hall]

Hi folks,
   I have a problem with my HQ-170 when using AVC. Strong signals tend to
"pull" the receive frequency somewhat. It's most noticable on CW. I'm pretty
sure that it doesn't happen on AM, but a small change in frequency doesn't
really affect AM reception that much anyway, so I'm not certain. With the
AVC off, signals are stable regardless of the RF gain setting. The regulated
+105 volt supply is stable. I checked the BFO tube tonight and it checked
bad (low emission) so I have to replace that, but the BFO still works. Could
a tube with low emission cause such an effect? I believe that the AVC
voltage is causing the problem somehow, but I'm not sure where. Has anyone
seen this problem before? Could a leaky cap cause this? Many of the old caps
have been replaced, but all the disc bypasses are original.
   This is the last thing I need to fix in order to be finished with this
very cool receiver. If you can offer some advice I'd sure appreciate it.
73,
Doug Hall, KF4KL

Looking for:
Hammarlund HQ-160 or HQ-180
National NC-183 or NC-183D
Hallicrafters SX-99 or SX-100
Hallicrafters HT-32 or HT-32A