[Hammarlund] Fw: Hq170 hum

[Mike Taylor]

----- Original Message -----
From: "Mike Taylor" <reel2reel@hotmail.com>
To: <crgrbrts@verizon.net>
Sent: Saturday, February 21, 2004 1:13 AM
Subject: Hq170 hum


> Craig, Its unusual for audio output leads to pick up hum, but not
> impossible. Generally, the speaker isn't sensitive enough to reproduce hum
> picked up by output leads. The hum is probably at the output of the audio
> finals. But you could try moving the leads away from the power supply,
> tightly twist them, and snug them to chassis. Or try sheilded cable from
the
> transformer output to the speaker. Also tightly twist tube filament leads
> and snug them to chassis if you haven't done so already. These steps
solved
> hum problems in  receivers I've had in days gone by. Before anything else,
> notice that your owners manual says to try reversing the plug in the wall
> outlet. Sometimes it helps...sometimes not. (Does with my HQ-180).  A good
> earth or waterpipe ground may do the trick... (Even the round ground hole
on
> the outlet) but  sometimes not. These are last minute things that have
> worked for me at various times with different radios over the years.
Perhaps
> your re-built power supply needs a little refinement.(Maybe more MFD). And
> don't forget that it could be a tube. Even unplugging another piece of
> equipment from the wall outlet or disconnecting an antenna lead from it
can
> reveal the culprit. We all have such stories and I'm sure you'll hear many
> more from the very technical to just dumb luck. Keep us posted on your 170
> odessey. 73's, Mike
>