Hi:
When listening to a broadcast station using an analog receiver you just tune back and forth near the station frequency
until you hear it, but that does not work for military radios where most of the time there is no transmission. Hence
the need for frequency or wavemeters like the BC-221 and the LM series to set them on the assigned frequency. The
calibration books for these meters were machine generated for each serial number unit. This was long before computers.
The later FR-149B/USM-159A Frequency Meter uses a long 35mm film strip and an optical readout to get the 0.01% accuracy,
and again is custom made for each serial number meter. But the need for them has almost gone away with the advent of
synthesized radios. But there must still be some analog radios in use since the manual for mine has a date of March
2006. Note they are accurate signal generators (to set receivers) and have a hetrodyne capability to set transmitters.
http://www.prc68.com/I/USM159.html
When working at a microwave company we used cavity wavemeters where at
resonance there was a suck out.
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
-------- Original Message --------
In a word,Wavemeters. Classic US onwas the BC221 with built in 100kHz crystal
calibrator
http://radionerds.com/index.php/BC-221
British was the "Class D"http://www.royalsignals.org.uk/photos/classDno1.htm
For UHF and Microwave it was Lecher lines or cavity wavemeters.
Robert G8RPI.
From: Scott Stobbe <[email protected]>
To: Discussion of precise time and frequency measurement <[email protected]>
Sent: Sunday, 12 February 2017, 6:08
Subject: [time-nuts] Vintage Frequency Measurement
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
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