[Milsurplus] Command Set Transmitter Keying

[Mike Morrow]

Michael wrote:

>The Command Sets were primarily used for local communication via AM voice.

Especially the USN's AN/ARC-5.  The most commonly-used receiver control box
(C-38) and even the C-27 and C-125 units provided no way to turn on the
receiver's BFO.  The most commonly-used transmitter control box (C-30A)
had a screwed-down cover over the CW-TONE-VOICE switch to discourage one
from taking it out of VOICE, and to eliminate an unneccessary control.
Plus, none of the AN/ARC-5 transmitter control boxes (C-29, 30, or 30A)
had a CW key.

>I assume the CW function was added as a backup in the event of a failure of
>the Liaison Set transmitter. 

Well, maybe, but the command sets were likely installed in more aircraft
that did not have liaison sets than those that did.  I suppose CW capability
was present because it was easy and cheap to provide, had traditionally been
provided, and could be used in the event of modulator failures of various sorts.

An AFJROTC officer (Col., USAF) at my high school many years ago had entered
the US Army Air Corps in the late 1930s, then made the USAF a career as a
pilot through Vietnam.  (Man, was he old to us high school kids!)  I was a
ham back then, and though he had no interest in the radio hobby, he demonstrated
very good capability in practical Morse operation.  I suspect one would not find
that skill in the repertoire of combat pilot capabilities today.

>Could the chirp have been a normal and acceptable feature for this set
>in its role as an emergency backup radio?

Possibly, but 65-year-old equipment sometimes exhibits characteristics today
that it may not have when it was new.  Who knows what a new-made, stock, complete
original configuration, command set that is supplied by robust aircraft engine-on
DC power and feeding the aircraft antennas for which the set was designed would
sound like?  I don't know of any instance where *all* of these conditions (the
exact environment for which the gear was designed) have been met in the past
sixty years or so.

Mike / KK5F