[Johnson] Johnson 500 bias voltage

[David Harmon]

Hi Bob.....
It's a great rig....you'll love it!

A lot depends on which PA tube it has.
Go to the AM Forum and read this thread I made some time ago...
http://amfone.net/Amforum/index.php?topic=33684.0



73

David Harmon
K6XYZ
Sperry, OK


-----Original Message-----
From: Johnson [mailto:johnson-bounces at mailman.qth.net] On Behalf Of Robert
Nickels
Sent: Sunday, January 29, 2017 3:25 PM
To: JOHNSON LIST <johnson at mailman.qth.net>
Subject: [Johnson] Johnson 500 bias voltage

Working my way through a basket-case Johnson 500 power supply-modulator 
and have a question that someone who'd been there and done that might be 
able to answer.    The book specifies the bias voltage at -150VDC but  
I'm seeing over 300 volts unloaded and around 225 with just the slow 
release and HV relays engaged (PTT keyed).    This is without the RF 
unit connected and that load will further reduce the voltage, but I'd 
like to verify that it's OK before doing that.   Most of the iron on 
this deck has been replaced but the LV transformer is the original based 
on wire colors, so I'm hoping that it's just the way it is without load.

Thanks and 73,

Bob W9RAN

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