FT-243 Frequency Codes
 

I read here or somewhere about how to translate the numbers stamped on
a FT-243 Crystal
to be able to tell the Crystal's Frequency. I have some with these
numbers stamped on them,
and want to be certain of the frequency, since the ink with the exact
Frequency has long since faded. TNX ex 73, Mike

FT-243 Frequency Codes
 

"KE9EX" wrote in message
oups.com...
I read here or somewhere about how to translate the numbers stamped on
a FT-243 Crystal
to be able to tell the Crystal's Frequency. I have some with these
numbers stamped on them,
and want to be certain of the frequency, since the ink with the exact
Frequency has long since faded. TNX ex 73, Mike


If you don't get an answer--the FT-243 rocks are fundamental cuts. It
would be easy to build an untuned Colpitts oscillator, and use a counter
to determine the crystal frequency. A simple c-mos IC oscillator would
probably also work.

Pete

FT-243 Frequency Codes
 

ANOTHER WAY IS TO USE AN MFJ ANTENNA ANALYZER - JUST USE ALLIGATOR CLIPS TO
HOOK THE XTALS PINS TO THE SO-239 ON THE ANALYZER -

TUNE ACCROSS - THE RESONANT FREQ WILL SHOW AS A 1:1 ON THE ANALYZER METER -
JUST READ THE FREQ OFF THE LCD.

- or -

USE ANY XTAL TRANSMITTER BY PULLING OUT THE BUFFER/DRIVER TUBE AND TAKING A
FREQ COUNTER OR SW RECEIVER NEAR THE OSCILLATOR TUBE AND KEY THE
TRANSMITTER.


WDØHCO - Biz


If you don't get an answer--the FT-243 rocks are fundamental cuts. It
would be easy to build an untuned Colpitts oscillator, and use a counter
to determine the crystal frequency. A simple c-mos IC oscillator would
probably also work.

Pete

FT-243 Frequency Codes
 

KE9EX wrote:
I read here or somewhere about how to translate the numbers stamped on
a FT-243 Crystal
to be able to tell the Crystal's Frequency. I have some with these
numbers stamped on them,
and want to be certain of the frequency, since the ink with the exact
Frequency has long since faded. TNX ex 73, Mike


Hi,

I wouldn't trust the crystal holder channel number to determine the
operating frequency.
It was very common after the war to reuse holders with different
crystal blanks. I've got a few here with paper labels giving
the actual crystal frequency, which has nothing to do with
the channel number embossed on the crystal holder.

Many surplus crystals were reground and mounted in the old holders,
here is a web site showing the technique used:
http://www.subdevo.com:82/n4jvp/crys...alGrinding.htm

73,
Ed Knobloch

FT-243 Frequency Codes
 

KE9EX wrote:
I read here or somewhere about how to translate the numbers stamped on
a FT-243 Crystal
to be able to tell the Crystal's Frequency. I have some with these
numbers stamped on them,
and want to be certain of the frequency, since the ink with the exact
Frequency has long since faded. TNX ex 73, Mike

I don't know offhand, BUT I know one of the Hints and Kinks books has
a Pierce crystal oscillator circuit intended as a crystal tester. One
FET, a couple resistors, and you take the output to a counter. Now you
know what any crystal is, even one that some ham has polished down to a higher
frequency. I have seen quite a few hamfest crystals that have been
modified since they were surplussed.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."