[ARC5] Drift in ARC-5s - and other matters.

[David Stinson]

----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at verizon.net>
Subject: Re: [ARC5] Drift in ARC-5s - and other matters.


>> These units were designed for aircraft to aircraft and aircraft to
>> ground operation using VOICE. Not CW.
>
> Sorry. That is wrong. They were used very heavily on CW. The
> main use of voice with them was in fighter aircraft before the AAF
> switched to VHF.

I'm sorry, Ken.  The SCR-274N was not, in fact,intended for CW.
CW operation and long-range comm was the provence of the Liaison set.
Command Set CW was a matter of emergencies and for
radio direction finding.  The AN/ARC-5 transmitter control box
did not even include a key.
Also- both sets did have MCW positions and, when the key was
used, it was very likely to be used in this position.
The AAF never, during the war, "switched to VHF" as a hard policy.
VHF and HF use was a matter of location, equipment availablity
and unit.  They were used concurrently throughout the war
and long afterward, by both the AAF and the Navy.

The reason for the wide IFs was a "lessons learned" decision, designed
to make allowance for errors in frequency setting and drift with 
temperature.
Too-narrow IFs would result in members of your flight missing
transmissions from other members.  Then the pilot, *who had primary
control of the Command Set,*  would start cranking away and the
next thing you know everyone is on the wrong freq and no one can talk.
Which lead to a lot of griping about "bad" radios when the real
problem was "between the headphones."
This was the very reason the later sets were "stablized" (circle-S marking)
and the crank tuning handles were removed.

You are right about the keying- everything gets keyed, which made
for slow QSK.  I would not want to run the rig on CW regularly.
I don't think the multiple relays would take daily CW operations.
If  a person is using the selector relay in a "ham rig" configuration,
that's pretty OK.  But if you're running the "whole hog" rig,
CW should be occasional.  It's really a 'phone rig.

Kindly,
David S.