Rick & Charlotte wrote:
>your wrong Kevin . thay do .. you just have to ask .. our UHF mircor
>has xtals from them and thay are .. thay work fine .. and we use the
>100% in the shop with not a problem
>
I did ask.
You had better look to see if they changed the compensation components
in your elements. In the fall of 2002, I had a very lengthy
conversation with the engineering department of West Crystal after they
informed one of my list members that if he sent his element in that it
would be "Temperature Compensated". The engineer finally admitted that
West Crystal does not change the Temperature Compensation components
inside the element/ICOM. He said they only either change the parallel
capacitor to net the crystal "on frequency" with the trimmer centered,
or grind it to do so.
I'm not saying they aren't a good firm to deal with, but I am saying
they do not temperature compensate elements or ICOM's.
On the other hand, you don't need to believe me, simply call them and
ask....and remember to be very specific, as they will try to con you
into believing that netting and compensation are the same thing; which
they are not.
Things to consider...
ICM and BOMAR warrants not only their crystal, but the element for
life. ICM and BOMAR temperature compensates the crystal AND element
together. I don't know of any other companies that ACTUALLY replaces
the temperature compensation PARTS (capacitors, etc.) to make a 2 PPM
element REALLY 2 PPM, or a 5 PPM really 5 PPM and so on. There are lots
of companies willing to build a crystal and install it into a element
and NET it on frequency, but none I know of (except BOMAR and ICM)
really does the temperature compensation correctly. If there are
others, I'd appreciate knowing about them.
Just because you buy a 2 PPM crystal and put it into a 2 PPM element
(ICOM) doesn't mean it will be 2 PPM over its entire operating range.
Each crystal unit must be compensated for individually in the element
chosen. The parts selected for YOUR element when it was made originally
*MAY* actually throw the frequency off *further* than 2 PPM with your
new crystal installed, so be aware that the $80 each you are paying is
not just for nothing. ICM places the channel element, ICOM, whatever
into a variable temperature chamber to vary the temperature and select
the proper high and low compensation parts (resistors, capacitors, etc.)
so the crystal actually stays on frequency. BOMAR does the same thing,
but at a reduced price over ICM, $25 per element if you supply the element.
ICM and BOMAR also verifies modulation characteristics when they build a
FM transmitter element that has the modulator inside it. Some crystals
produce frequency well enough but don't modulate well. Some crystals
will produce an asymmetrical modulation wave while some just won't
produce enough modulation period. Again, you aren't paying the extra
money for nothing.....
Kevin Custer
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