[ARC5] SCR-274-N Transmitter Dial Accuracy

[Mike Morrow]

Michael wrote:

>The military version Type K transmitter was specified as having a
>frequency precision of .03% of the dial reading.  The ATA and
>A.R.C.-built SCR-274-N transmitters met this specification.  Then came
>contract 1470-NY-41 and Western Electric...
>
>Apparently, WE continued to have problems since I have a BC-696-A,
>serial number 29387, originally purchased for parts but with the
>following legend on the dial: "Caution.  Do not rely on dial
>calibration for a frequency setting closer than four hundredths per
>cent."

I've come across several SCR-274-N transmitters with that legend in
yellow impressed on the tuning dial.

>Note that the ARC-5 transmitters were able to hold the .03% dial
>reading specification.

I have the same opinion that Dave Stinson just expressed, that these
specs were somewhat arbitrary and of "no never mind" in real use.

I have often wondered how the users of the MF/HF commands sets
netted the receiver to the associated transmitter, since there is
no MONITOR/NORMAL switch such as is found on the SCR-287-A and
AN/ARC-8 UASSF liason sets which allows the receiver to monitor
the output of the transmitter.  In the command sets, the receiver
output is disconnected from the audio bus and the modulator sidetone
output is applied to the audio bus when the transmitter is keyed.
Thus the receiver can't be effectively adjusted to the transmitter.
With stabilized preset lock-tuned communications receivers in the
AN/ARC-5, this would not be such a concern.  But with the tunable
receivers of the the ARA and SCR-274-N (and some AN/ARC-5), it must
have been common to develope a departure of the receiver tuning
from that of the associated transmitter in flight, with no easy way
to get the receiver back on frequency.  In any event, the frequency
tolerance of the transmitter dial would be immaterial.

>This wasn't the only time "the big company that had to help poor
>little A.R.C. out" messed up but rather serves as an example of a
>company that believed its own PR too much.

I have a great admiration of the efforts of Western Electric during
WWII.  I doubt that any other contractor produced the extremely broad
diversity of output in such gigantic quantity.  Certainly WE was without
any doubt a far far more important contributor to the war effort than our
favorite A.R.C. was or could ever have been.  

In the "command set" arena alone, all the truely innovative and useful
gear used in the typical AN/ARC-5 installation (R-4/ARR-2 VHF homing,
R-28/ARC-5 and T-23/ARC-5 VHF comms) were WE products.

Our beloved A.R.C. produced beautiful gear that was, ultimately, of
little *general* long-term value before obsolescence, outside the long
lives of the beacon band receivers.  They produced the ultimate MF/HF
command set just at a time when the sun was setting on MF/HF use for 
"command" communications.  This description applies to the AN/ARC-5,
but I beleive it is applicable even to the original ARA/ATA.

Mike / KK5F