[Boatanchors] How did they "pinpoint" frequencies way back when?

[Stuw7fe@aol.com]

In a message dated 4/10/04 19:59:12 PM US Mountain Standard Time, 
beaconeer@elite.net writes:


> Hello again,
> Something I've wondered about.  Back in the old days of, say WW II.  How did
> "intercept ops" accurately set their receivers for expected incoming
> messages?  Say that they expected a message from "Agent X" of the French
> underground on 6003 KC (I pulled that from the air).  How did the operator
> in England know they were actually listening on 6003.  After all, the agent
> couldn't risk long "on air" time calling CQ.  (I presume the transmitter
> used by "Agent X" was Xtal controlled and could be used to also zero beat
> the agents receiver to the same freq).   I'd say Xtal controlled receivers,
> but most of the receivers of the era seem to be VFO controlled.  In this day
> of everything digital it'd be no problem, but what about the old "drifty"
> days?   I know England used the BBC to send coded messages but the French
> Underground didn't have that luxury.
> 
> 73 from the "Beaconeers Lair".
> Phil, KO6BB
> 

Same way I do with my Drake 2-B, I'll bet. Turn on the 100KC crystal 
calibrator and mechanically set the hairline on the dial to match the even 100KC 
point.  The receiver dial would then be accurate within in that +/- 50KC range to 
at least 1 KC.  With the typical 4 to 6 KC wide IF's, they would have no 
trouble hearing ol' Henri LeClerque, (or Fritz Schultz for that matter......).  But 
I'll bet they did a lot of rocking the BFO around to be sure they weren't dead 
zero beat...although there was probably enough key click on Henri's (or 
Fritz's) little transmitter to be heard even at zero beat.

Stu  W7FE


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