[Hammarlund] My HQ-170A is a hummer!

[Craig Roberts]

Well, I've been using my eBay queen ex-basket case HQ-170A as a sort of
Hammarlund lab -- I mean, what did I have to lose?

As a last step in restoration, I've installed a high quality audio output
transformer to replace the low-end universal transformer stuck in there by a
previous owner. (One wonders what happened to the factory job).  My
transformer's a 5K to 3.2 ohm unit and, combined with my newly acquired
SP-200 speaker, puts out wonderfully high fidelity audio.

And that's the problem. The frequency response is now such that I'm hearing
a distinct 120 cycle hum under the signals. The hum is independent of the AF
Gain and RF Gain controls, so it's at the end of the chain. Now, the problem
could be lead dress, I suppose. There's quite a distance between the
transformer and the speaker terminals and the output lead runs right next to
the power supply components.  Since my receiver was modified and somewhat
butchered when I got it, I don't know where the lead's really supposed to
be -- suspended under the components?--snugged down against the chassis? Can
anyone tell me, please?  Also, if you have any hum reduction tips, please
share them.

Also, I'd love to get an original 170A audio output transformer (with the
dual 3.2 ohm and 500 ohm secondaries) if anyone's got such an animal to
sell.

Many thanks and 73,

Craig
W3CRR