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

Sun, 11 Apr 2004 06:39:08 -0400

Going along with this, the military used triple receivers (Hammarlund Super Pro
at the WAR station in MD) on each rhombic antenna system in a space diversity
arrangement. They were using AM and CW, not SSB. The receivers used were very
accurate and as Glen correctly pointed out, were never turned off unless they
had to be fixed. Even then, two others were still operating on that frequency.
If a person is used to spotting frequencies, you can be remarkable accurate. I
could do it thirty years ago, but now ... Three steps back and punt!	

DBF	

----------
From: Glen Zook <[email protected]>
To: Philip Atchley <[email protected]>; [email protected]
Subject: Re: [Boatanchors] How did they "pinpoint" frequencies way back when?
Date: Sunday, April 11, 2004 12:02 AM

The accuracy and stability of the receivers of the
World War II era are really not that bad.  The
bandwidth is fairly wide unless the crystal filters
are "cranked in" so a little drifting wouldn't make
that much difference.

Also, the receivers were never turned off except when
needing repair, thus were very stable.  In addition,
since the equipment was crystal controlled on the
"other" end, it would have been very easy to have a
crystal controlled oscillator on the receiving end to
"calibrate" the receiver.  Just turn on the frequency
"standard", "zero beat" your receiver, turn off the
standard, and wait for the scheduled transmission.

Glen, K9STH

--- Philip Atchley <[email protected]> wrote:

How did "intercept ops" accurately set their receivers
for expected incoming messages?

=====
Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

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