I have about 60 military crystals ..they are marked Channel 277 thru CH
347 .Anyone know if they are overtone ,and, know of a good way to
check them.. My grid dipper will not oscillate with them like it does
with basic fundamental crystals ,like 7193 KHZ. etc..THEY ARE FOR
SALE TOO..W4PQW

"mrhaney" wrote in message
oups.com...
I have about 60 military crystals ..they are marked Channel 277 thru CH
347 .Anyone know if they are overtone ,and, know of a good way to
check them.. My grid dipper will not oscillate with them like it does
with basic fundamental crystals ,like 7193 KHZ. etc..THEY ARE FOR
SALE TOO..W4PQW


Mr. Haney,

All crystals will operate on their fundamental as well as the overtone
modes. Too bad they aren't working in your g-dipper. What holder are they
in? Is it the old standard FT 243 (if I recall the number correctly).
Channel numbers could be for anything. A simple Colpitts osc could be built
to see where the fundamental is.

Use the SECOND circuit he
http://hem.passagen.se/communication/txo.html
Use both 150 Pf. The total of C3 and VC1 can be around 50-100 pf and it
should oscillate so you can measure / count the freq. R3 = 2.2K should get
it going.
73, Steve, K9DCI

mrhaney wrote:

I have about 60 military crystals ..they are marked Channel 277 thru CH
347 .Anyone know if they are overtone ,and, know of a good way to
check them.. My grid dipper will not oscillate with them like it does
with basic fundamental crystals ,like 7193 KHZ. etc..THEY ARE FOR
SALE TOO..W4PQW



Hi !

You are raising nostagig memories.
In 60 tales those FT241 xtals were used for home brew 455 kc xtal
lattice filters for SSB transmitters and home brew receivers.

Bought some 100 pcs of them from "Jan Xtals" surplus shop in USA.
Oscillator circuit for those FT241 xtals was not so trivial as for ham
band xtals (as you experience with your dipper)
Used BC-221 to select individual xtals for lattice filters.
You can check them by measuring series resonance.
You can also make a simple J-fet oscillator

Oh those surplus times
A school boy had to consult a couple of hotel porters to change
Finmarks to USD to buy surplus xtals from USA to make lattice filter to
contruct SSB transmitter.

73 de Risto OH2BT

Thanks Risto, exactly what I needed to know..I do recall something
about using them in a lattice filter.. I may try that.. W4PQW

mrhaney wrote:

Thanks Risto, exactly what I needed to know..I do recall something
about using them in a lattice filter.. I may try that.. W4PQW



Hi !

Go to library and borrow an old ARRL Single Side Hanbook (fourth edition
is very good) from 60 tales.
Maybe some of your friends is having it or it already stands in your own
bookshelf.

73 , Risto OH2BT