[Hallicrafters] HT-32 sideband oscillator

[Glen Zook]

Try using the crystal from the HT-32A in the HT-32 Mark I.  If the signal is there with the replacement crystal, then there is a very good chance that the crystal is the problem.  If the problem remains, then look elsewhere.

Glen, K9STH


On Tuesday, May 20, 2014 7:55 AM, Jeff <jeff at podengo.com> wrote:
 


All:

Looking for any advice. I've got an HT-32 Mk I that is dead on 40,15, and 10.  Works great on 80 and 20. I've traced the problem (I think) back to the sideband switching oscillator - the 12AT7 on the sub chassis.  I've got a carrier at 4.050 MHz, but none at 13.95 MHz. Rotating the band switch and function switches produce apparently correct behavior, turning the 4.050 oscillator on and off, but I can't get the 13.95 one to come on despite thorough cleaning of switches. Heterodyne oscillator seems to be ok- have a carrier at 21.5 MHz. 

Resistance is way off on the grid of the 13.95 side -  pin 7 is supposed to be 65k, and it is reading 101k.  Grid 2 is supposed to be 32 vdc, but mine is reading minus 30 vdc.  That's the value on the schematic of the HT-32A, so wondering if that's a typo.

I'm having a hard time accepting that a crystal somehow has gone bad, so before I go to the expense and hassle of replacing it, I thought I'd solicit some other opinions. Replaced the 12AT7 with three other tubes - same results.  I've got an HT-32A sitting right next to it, which behaves as expected - so it doesn't seem to be my testing protocols.


So, instead of shotgunning components in the sub chassis, anyone have thoughts on a more surgical approach?


Jeff
WB3JIH

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