[Hammarlund] SP-200 Audio Bypass

[Al Parker]

Hi Joe,
    A bypass like that is normal in the audio output cathode, as is the
resistor.  As for the resistor wattage, I'd try what's in there to see how
warm it gets at normal audio levels that you use, I'd suspect that it'd be
OK.  The 800 vs. 750 ohm is within 10% and is OK.  47 mfd for the cap also
is fine, electrolytics have a even higher tolerance spec, and it's better
to go a bit higher in this application than lower.
    I did a complete refurb on an SP-200 series, you can see it in the
Service section of The Hammarlund Historian website:
http://www.hammarlund.info
    I hope it helps you out.  They're a nice rcvr, great audio output.
You oughta ck the p.s. output voltages tho', they're probably low, and
easily fixed.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.boatanchors.org
http://www.hammarlund.info

----- Original Message ----- 
From: "carolew" <carolew at bellatlantic.net>
To: "Revcom Electronics" <revcom at wbsnet.org>
Cc: <boatanchors at mailman.qth.net>; <hammarlund at mailman.qth.net>
Sent: Tuesday, July 18, 2006 7:27 PM
Subject: [Hammarlund] SP-200 Audio Bypass


>     I just picked up a very nice Hammarlund SP-200 that plays like a
dream. I
> will undoubtedly be peppering you folks with questions as I work on it.
The
> collective knowledge here boggles my mind.
>
>     In looking at the 2nd AF stage, I see some issues:
>
>     1.   There is supposed to be a 40 mfd/150V cathode bypass cap. Was
there
> any production change that eliminated this cap? Any reason to eliminate
it? If
> not, I plan to install a 47 mfd/150V cap. Any problem with this?
>
>     2.  The cathode-bypass resistor is supposed to be 750 ohm/10W. The
one in
> there measures about 800 ohms but is only a 6-watt Koolohm unit. Is that
> wattage too light? Should I replace it with a 750-ohm/10W unit?
>
> As always, thanks!.
>
> Joe Connor
>
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