RadioBanter - View Single Post - Temperature compensation in channel elements

Ralph Mowery · November 7th 18, 03:34 PM posted to rec.radio.amateur.homebrew

In article ,
says...

Anyone know of a company that will re-crystal channel elements for LMR amateur radio equipment?

Doubt that any company will now that International Crystal went out of
business.

Here is a word from a while back on companies that will make you a
crystl and you can put it in the element .

As long as it is amateur radio that should work. I have just
recrystaled a couple of elemnets for the GE Mastr ll units and they seem
to be ok.

Below is the copy of a message.

There appear to be two choices. Bomar had left the business, but
returned after International Crystal shuttered their doors.
Unfortunately the price is rather steep ($100+ for a pair of loose
crystals!). QuartsLab in England however, is around half that price for
great quality. They can make standard inflection (25 deg C) crystals or
elevated inflection (50 deg C ?) crystals for GE rather easily. It is
helpful to give them as much data as possible. Don't expect them to just
do the math for you, for example. Give them the Operating frequency and
the Fundamental (crystal) frequency. Be sure to specify and document
High Side or Low Side injection for the RX side.

When they made my first pair for UHF, they mismanufactured them for the
wrong load. They ended up ~180KHz high. Second go-around though, they
corrected this error (free of charge) and the new set literally dropped
right in with only a small adjustment to the trimmer needed. The trimmer
is near center & stability is excellent.. If I feel like going through
the work of selecting a exacting compensation capacitor with the right
coefficient, it will make true 2C spec over the whole temp range. For my
climate-controlled setting, it keeps to +/-2ppm easily as-is.

Bomar can be found at http://www.bomarcrystal.com. QuartsLab can be
found at http://www.quartslab.com and reached at .
Dave Hayes at QuartsLab was very helpful and accommodating in our
dealings. He will be seeing more business from me. Bomar was always good
to us in the past, but like most of us, I shop for best value. A friend
recently bought from them also & we had no problems, only a longer wait
time than from England. (8 weeks vs. about 6 weeks)

73,
Matt W6KGB