[ARC5] ATA, SCR-274-N, AN/ARC-5 Transmitter Calibration Crystal Y-50

[Mike Morrow]

> There seems to be a widespread belief that a crystal was fitted
> to each transmitter and carried aloft on each flight,

That is a rare case of common belief being absolutely factual.

> but the maintenance manual says only that one may be plugged in for
> the purpose of checking the dial calibration.

Well...not quite.  

The ARA/ATA and SCR-274-N manuals both contain the following statement:

"Y-50 is a peizo-crystal resonator...A similar crystal unit, but of
a different nominal frequency, may be substituted for the unit normally
supplied..." 

The AN/ARC-5 manual states the same in slightly different wording:

"Y-50 is a quartz crystal...If desired a similar crystal unit, but of
different frequency, may be substituted for the unit normally supplied..."

> Does anyone know whether the transmitters were supplied with
> crystals fitted, or whether the sockets were normally empty?

Y-50 was **always** supplied.  If it is missing, then the transmitter has
likely been the victim of ham "improvements".  :-)

73,
Mike / KK5F