[Hammarlund] update HQ-180 issues

[Roy Morgan]

On Dec 16, 2014, at 8:45 PM, Robert Sauvan <rsauvan at beyondbb.com> wrote:

> ...my quest to find why it has what I feel is lousy audio. Still sounds like crap.

Bob,

Measure the voltage on the grid of the audio output tube.  That is fed with a “Couplate” in my diagram. If the cap in there is leaky, your output tube is driven to very high plate current. 

Also measure the 6AQ5 cathode voltage. Suspect the cathode resistor bypass cap.


> ...RF Gain ... only really seems to do anything at all for about the first 1/4 of a turn after you turn on the radio. Beyond that it has no affect on the gain other than sounding wide open ... Maybe I need a new pot?

First measure the resistance from the ground end to the wiper as you move the pot (power off).  It should change smoothly with out any jumps or blank spots.  Here an analog ohm meter is your friend.  You can also measure the voltage that pot controls - likely it is in the cathode line of one or more tubes (I did not examine the circuit).

Roy



Roy Morgan
RoyMorgan at alum.mit.edu
K1LKY Since 1958