On Apr 22, 3:05*pm, Darrell wrote:
This is typical of many receivers. It is generally caused by variations
in local oscillator injection to the mixer. As you change the amount of
capacitance with the tuning capacitor, you change the amount of feedback
in the oscillator. Most oscillator circuits suffer from this.

73,
Darrell, WA5VGO

Hello. I've been restoring a Hammarlund HQ-145 that has been neglected
for many years. After performing the RF alignment, I noticed that the
sensitivity at 10 Mc on the 10-30 Mc range is about 10 dB worse than
when tuned to 10 Mc on the 4-10 Mc range. This was even after
adjusting the 10-30 Mc ANT and RF coils as instructed by the manual.

The sensitivity is actually much better at 30 Mc than it is at 10 Mc
on that band setting. I wonder if this was a design compromise? Or is
there still something flaky with my HQ-145?

I would appreciate it if someone else with a working HQ-145 would
please check whether theirs operates the same way. Just tune into WWV
at 10 Mc on both band settings and see if there's much difference in
signal strength. Thanks!

Tnx,
Joe K9LY

You are correct about the injection, but the HQ-145 did not suffer
from this, at least mine did not. Check the Oscillator injection -
you will probably find that it is down due to a bad component. Either
the tube is weak or you have a bad bypass cap. Also check the values
of all of the resistors with a meter.

Tim AA6DQ