[Hammarlund] HQ-180 Mods

[k2cby]

Ray,

You may have less trouble than you think.

You say that the static is present even when the volume control is all the
way down.

This means that the source of the noise is somewhere downstream of the audio
gain control.

The only things in that neighborhood are the audio amplifier and the output
stage.

Take a rather large (.01 to 0.1 uF) capacitor. Connect it between the
control grid of the output tube and ground. If the noise goes away, the
problem is somewhere between the volume control and the grid of the audio
output tube.

My bet would be a leaky coupling capacitor between the plate of the audio
amplifier and the grid of the output tube.

If that is OK the next place to look is the cathode bypass of the audio
stage.

/Miles, K2CBY

 

Miles B. Anderson, K2CBY
16 Round Pond Ln.
Sag Harbor, NY 11963

k2cby at optonline.net