[ARC5] CW Use in Fighters

[Mike Morrow]

> I even recall seeing a aircraft radio control box with a built in
> CW key in an old issue of the Fair Radio Catalog, but did they 
> actually ever plan to use that mode?

US Army HF Command Sets
SCR-A*-183/283   Receiver is VOICE(MCW) only.
(1932)           Transmitter is TONE(MCW), CW, or VOICE. 
                 (Pilot control has key.)

SCR-274-N        Receiver is MCW(VOICE) or CW.
(1941)           Transmitter is TONE(MCW), CW, or VOICE.
                 (Pilot control has key.)
                
US Navy HF Command Sets
RU-*/GF-*        Receiver is MCW(VOICE) or CW (except earliest receiver).
(1932)           Transmitter is MCW(TONE), CW, or VOICE. 
                 (Pilot control has key.)

ARA/ATA          Receiver is MCW(VOICE) or CW.
(1940)           Transmitter is TONE(MCW), CW, or VOICE.
                 (Pilot control has key.)

ARB/ATB          Receiver and Transmitter are VOICE/MCW/CW capable.
(1942)           (Pilot control has key.)

AN/ARC-5         Receiver is VOICE(MCW) or CW capable, but in MOST
(1943)           installations the pilot controls allowed only VOICE
                 (there was no VOICE/CW selector on the C-27 and C-38
                 controls).
                 Transmitter is TONE(MCW), CW, or VOICE, but in MOST
                 installation the pilot controls alllowed only VOICE
                 (the TONE/CW/VOICE selector has a cover installed
                 over it, and the pilot control has NO key).

> ...in CW or Tone modes the transmitter dynamotor keeps running continuously
> whereas in Voice mode it only spins up when the mike key is pressed

That's an essential arrangement in all dynamotor-supplied sets, all the way
up to the AN/ARC-38A.  One doesn't want the dynamotor energizing/de-energizing
with each closure/opening of the key.

> But for the SCR-283 installation for the P-40D they point out that the
> receiver lacks a BFO so CW is not available.  So if the earlier radios
> lacked the capability, why were pilots schooled in Morse Code?

The USAAC SCR-A*-183/283 sets had MCW capability on receive and transmit,
and had a key on the pilot's control.

The USN RU-*/GF-* sets, except for the earliest receiver, had CW and MCW
capability on receive and transmit, and had a key on the pilot's control.

That said, I doubt that many pilots had a real practical knowledge of
Morse beyond reading navigation beacon IDs.  I had an instructor in high
school who joined the USAAC in 1937 and was a pilot for three wars.
He told me he would not have been of much service actually communicating
in Morse at any but a snail's pace.  And he was pre-WWII old-school!

> But I have yet to find any written down historical cases in which pilots
> in single seat fighters used CW for two way communications.

That's because it was rarely, if ever, required.  The US Navy came to that
conclusion by the time the AN/ARC-5 sets were being designed in early WWII.
In most AN/ARC-5 installations, the pilot lacked receiver and transmitter
controls for frequency, mode, and even power on/off.  No key was provided
on any AN/ARC-5 transmitter control. 

Though not a command set, I question the value of the AN/ART-13* pilot's
control box in USAAF AN/ARC-8 installations.  The pilot had no control of
the AN/ARR-11 (BC-348-*) receiver, so what good was the C-87/ART-13 which
allowed the pilot to select channels and mode on the transmitter?

The USN's equivalent system, the AN/ARC-25, utilized the AN/ARR-15 receiver
with the AN/ART-13.  A pilot's control makes sense there, such as the
C-733A/ARR-15A for the R-105*/ARR-15, and the C-740/ART-13 for the T-47/ARR-13.
However, the AN/ARR-15 can NOT be remotely switched between VOICE and CW mode.
Prior to arrival of the AN/ARR-15, the ATC or AN/ART-13 was often used
with the remote spline-tuned ARB, so even then there was some value to the
AN/ART-13 pilot control.  But none of this is true for USAAF installations.

The AN/ARC-2* is an all-in-one-box HF command set that, with the loss of
importance of the HF command set, was typically employed in USN and USCG
aircraft after WWII as a baby liaison set.  (It wasn't at all suited for
that.)  Its pilot control has no Morse key, nor even the capability to
change emission mode.

73,
Mike / KK5F