[Hammarlund] HQ129X Distortion

[Joel R. Hallas]

An interesting feature of a 6SS7 is that it draws half the filament current
of otherwise similar tubes such as the 6SK7. As I remember (never a good bet
<g>) 0.15 vs. 0.3 A. I always figured that they used those to save on power
transformer copper. I'm not sure how close to the limit they are, but I've
always stuck with 6SS7s in my '129X, and been happy not to have to replace
the c. 1946 power transformer.

Regards, Joel
Joel R. Hallas, W1ZR
-----Original Message-----
From: hammarlund-bounces at mailman.qth.net
[mailto:hammarlund-bounces at mailman.qth.net] On Behalf Of Larry Asp
Sent: Friday, April 04, 2008 6:00 PM
To: hammarlund at mailman.qth.net
Subject: [Hammarlund] HQ129X Distortion

The subject of audio distortion  with the rf gain control turned up full on
the HQ129X has come up a few times, and the standard advice given has been
to back off the rf gain control. This problem existed with my set up until
today, even though I have gone through it and replaced all the paper caps
etc. What often happens with the HQ129 is their owners replace the  4 6SS7
tubes in it with one or more 6SK7s. The 6SK7 does work in the set and gives
it a bit more gain (some say), but its not an exact substitute. Such was the
case with mine - one of the 6SS7s had been replaced with a 6SK7. I had the
good fortune of purchasing some NOS 6SS7s recently (JAN type) and replaced
the 6SK7 and the  old  6SS7s with with them, and - the distortion went away
- except for the signal from a broadcast station (10KW) located about 2 - 2
miles from my house (which I can control by backing off the RF gain). Hope
this helps - worth a try if you can find the tubes.
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