[Hammarlund] HQ-129-X Mixer Noise

[Frank Barnes]

I'm sure you are right about that.  It seems to have more "hash" noise than
a Hallicrafters S-40B using the same antenna, perhaps because it's a better
receiver?   The current antenna is ~400 feet long, running in 3 directions
at a low elevation in the back of my lot.   I'm thinking about a shorter,
dedicated antenna for it (I live on a 1 acre heavily wooded lot), perhaps
just 100 feet.  I'll research antennas that have any noise rejection
capability (would have to receive from the South and block from the North)
and also intend to shut the down the AC in my house, breaker by breaker, to
see if my house is the culprit.   And, with propagation so lousy around 40
meters, there is not much to be heard until evening/night.  Even my Yaesu
hears almost nothing until evening.   The HQ129 seems to hear what the
Yaesu hears at night, but has slightly more hash noise.   Wish the sunspots
were back!

On Wed, May 22, 2019 at 1:04 PM <djed1 at aol.com> wrote:

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