[Hammarlund] HQ-129-X Mixer Noise

[djed1 at aol.com]

Hi Frank-If the noise drops when you disconnect the antenna, then its not caused by the radio.  These days most of us (in suburban locations) suffer with high noise levels caused by the multitude of electronics around us.  While you could theoretically improve the sensitivity of the radio by modifying it, in practice it would make no difference since your S/N is determined by outside noise.  You could try improving your antenna by getting it away from noise sources.  For example, my beam is further away from my house and is higher than my wire antenna, and the beam has somewhat less noise.  These days, even the older radios have adequate sensitivity given the high external noise levels most of us live with.  Ed  W2EMN

-----Original Message-----
From: Frank Barnes <fbw4npn at gmail.com>
To: hammarlund <hammarlund at mailman.qth.net>
Sent: Wed, May 22, 2019 11:58 am
Subject: [Hammarlund] HQ-129-X Mixer Noise

I'm new to the group and have an old subject which I'm sure has been
discussed multiple times.  I've restored an HQ-129-X and I really like
it.  It was a lot of work to bring it back!
I really like the quality and love the 3-IF system.  I'll use it mostly on
40M CW and for some general SW listening.
However it seems to have a lot of "noise" - sort of a background hash.
 More than some other receivers I've used, including my Halli S-40B.
Disconnecting the antenna eliminates the noise so I think that means I'm
hearing noise radiated from power lines, appliances, etc.

Am I hearing mixer noise?  I've read about replacing the 6K8 mixer with a
very expensive 6SB7Y (requires some rewiring).

Does anyone have advice regarding quieting the mixer noise, other than tube
replacement?

I'm also interested in replacing the RF tube with a better one - 717A?
6AC7? 6BZ6 mini?  Any advice/experience?

-- 
Frank Barnes
W4NPN
Chapel Hill, NC
Grid Square FM05
Cell 919.260.7955
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