[ARC5] [Milsurplus] Anyone Else Run an ARC-2?

[Bill Carns]

Not knowing the exact performance of an ARC-2 PTO during the transmit heat
cycle, here is a suggestion.

With the cover on (the way you have been using the rig) document as
carefully as you can the drift vs. time while in transmit.  If nothing else
just make  a gross "1 kHz in X seconds" measurement.

Then, take the cover off and put a small fan on the PTO so that it sees room
temp air during the transmit key cycle and measure it again.

This will tell you where the culprit is and I suspect that it is drifting
due to temperature in the box.

1 kHx sounds a bit excessive but you need to remember that this was 1945 and
the AM receiver bandwidths were measured in 10s of kHz and a 1 kHz drift was
not that noticeable.

You may have lost a temp compensating cap in the PYO though. We see that all
too regularly now.  They are getting old.  --  like me.


Bill Carns, N7OTQ
K0CXX, Trustee MRCCC
President Collins Collectors Association
Editor, Signal Magazine
Founding Member # AC94-0009
512 618 2762 (Cell + VM)
512 847 7010 (Home + Fax)




-----Original Message-----
From: milsurplus-bounces at mailman.qth.net
[mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of David Stinson
Sent: Sunday, August 18, 2013 8:38 AM
To: mrca at mailman.qth.net; milsurplus at mailman.qth.net; ARC-5 List
Subject: [Milsurplus] Anyone Else Run an ARC-2?

Has anyone else put an AN/ARC-2 on the air?

On key-down, the PTO drifts about a KC.
Before I take the cover off this gorilla of a radio and wrestle it to the
ground, was wondering if this is common to the ARC-2 or if I need to look
for a bad cap on the 250 VDC buss dragging it down on PTT.

73 DE Dave AB5S

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