[Heathkit] Powering the Heath HX 20 SSB transmitter

[WQ9E at btsnetworks.net]

John,

I had no problem finding a couple of HP-20 supplies on ebay a few years ago so they do show up.  The older UT-1 (which was sold for the earlier AM mobile twins) will also be fine.

If you reset the grid bias in the HX-20, it should be fine with the HP-23 supply since the additional voltage won't hurt the 6146 as long as you adjust the other operating potential.

Since the HP-23 series use voltage doubling you cannot use the simple expedient of switching to a choke input filter to reduce the output voltage.   If you want to do a more serious redesign, you might be able to convert the existing HV section to a full wave type and then stack it on top of the LV supply to generate the proper HV.  Take a look at the "totem pole" design Tektronix used in the regulated supplies for their 500 series tube type scopes for an example.  In these supplies the separate supplies are stacked to provide the higher operating potential.

Rodger WQ9E

----------------------------------------
From: John King <k5pgw at yahoo.com>
Sent: Friday, February 25, 2011 9:08 PM
To: Heathkit at mailman.qth.net
Subject: [Heathkit] Powering the Heath HX 20 SSB transmitter 

________________________________
 When I bought my first HX 20 as a kit about 50 years ago, I bought a HP 20 
power 

supply to power it. I now have a nice HX 20 again and no HP 20 power supply. I 
do have a HP 23A which puts out about 200 more volts of HV and can be switched 
from 300 volts to 275 volts low voltage.

Has anyone successfully powered an HX 20 transmitter with a HP 23A?  If so, I 
would appreciate any tips you can give me with that combination. Your input will 

be greatly appreciated. Thanks and 73, John, K5PGW 

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