[Hammarlund] WTB;Power Supply (ddswl)

[Al Parker]

Hi Folks,
    Here's what I wrote about p.s. reqmts several yrs ago when I did an 
SP-210LX.  You can find it and more on my website at 
http://www.boatanchors.org/SP200.htm
---------------------------------
(before doing anything in the p.s., but with a recapped rcvr)
I checked voltages from the power supply, and at tube sockets.  The supply 
should give +140vdc, +270vdc, +385vdc, -50vdc and 6.3vac.  The high voltage 
lines were -50, 110, 240, and 330, & I measured  10, 4, 65, & 42 ma on each. 
I had already changed the AC line tap on the transformer to the 125 VAC 
position, and my line voltage was 122, so I expected things to be close, 
maybe a little on the low side, but not this much, particularly on the 
140volt screen supply.  The tubes were only seeing about 100v on the 
screens, after their dropping resistors.
   The power supply, at 60 lbs, is not under designed.  The screen voltage 
is supplied from the 270vdc line using a voltage divider/bleeder resistor, 
which checked out OK when cold, but apparently drifted high when heated 
under power.  It was changed to supply close to 140vdc, and receiver 
sensitivity seemed to improve.

------------------------------------

----- Original Message ----- 
From: <DJED1 at aol.com>
To: <w5jv at hotmail.com>; <hammarlund at mailman.qth.net>
Sent: Friday, November 20, 2009 12:33 PM
Subject: Re: [Hammarlund] WTB;Power Supply (ddswl)


>I think all the voltage requirements are spelled out in the military tech
> manual for the BC-779 etc.  Probably the only missing info is the current
> requirements.  I can probably dig up the info if anyone is  interested.
> Ed
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