[Collins] Crystal Mfg.

[Gerald]

On Sat, 2005-12-17 at 09:25 -0500, Merle wrote:
> 
> Hello to the list..
> 
> Several months ago someone was listed as manufacturing crystals for Collins and other equipment. I have not been able to locate who this person / Company was. If someone could provide the information I would sure appreciate it. Thanks and MERRY CHRISTMAS to all..
> 
> Merle W1GZS
> 
> _
The one I recommended was International Crystal Manufacturing
http://www.icmfg.com/ in Oklahoma City. Their crystals have always been
first rate and never needed to be returned. I can't say other places
have done that well though their prices were cheaper.

The best procedure if they don't have the calibration constants for the
S-line (which they should have) is to send them a crystal that you know
works right and have new crystals made to the same operating parameters.
I'm sure the crystal runs in parallel fundamental mode, but I can't tell
from the schematic what the shunt capacitance should be. Standards are
32 pf and sometimes 20 pf, but Collins could have chosen some other
value. I can't tell from the schematics what the load C is because the
grid to ground C is all strays in the transmitter, has an added 15 pf
capacitor in the receiver. The case is a military nomenclature HC-6U.

Be sure that the crystal frequency isn't the receive frequency that they
understand which you are specifying. The Collins manual lists all the
standard frequency ranges and crystal frequencies to match. Generally
the crystal on the low bands is 3.155 MHz above the receive lower band
edge and on the high bands the crystal frequency is half that. E.g.
(Flo - 3.155) / 2.  Tolerance .005% or better. Better costs more.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer