[NLRS] Crystals

[Dr. Gerald N. Johnson]

Rather than a custom crystal, Surplus Sales of Nebraska has a few 
hundred frequencies in stock at quite reasonable prices. 
http://www.surplussales.com

Remember that fundamental crystals generally are 20 MHz and lower, third 
overtone 20 to 60 MHz, 5th overtone 60 to 100 MHz, and 7th overtone 100 
to 140 MHz though there can be variations. Point is that if you need an 
overtone crystal its worth looking for one calibrated for a different 
overtone because it will oscillate just fine on all the possible 
overtones and the frequency will be very close to newF = markedFrequency 
* new Overtone/oldOvertone. Example a 3rd overtone 45.000
  MHz crystal will oscillate at 75.000 MHz when the oscillator is tuned 
for that frequency. That is also true of crystals sold by Mouser and 
Digi-Key who have a large selection of stock frequencies.

Fair Radio has a bunch of crystals in stock too. http://fairradio.com

73, Jerry, K0CQ

On 4/10/2018 10:34 PM, Doug Reed wrote:
>
>
> Please note that none of these vendors make compensated channel
> elements like ICM did. ICM would sell you the loose crystal but for
> triple(?) the price they would install the crystal, then recheck and
> adjust the temperature compensation components in the channel element.
> If you need a guarantee of temperature stability over the full temp
> range, then buying a loose crystal might not solve the problem.
>
> But you can probably do as well or better if you add some sort of
> heater element to temp stabilize the crystal. You can try the old
> school method using a 30-40 degree Celsius PTC heating resistor. Or
> there are several precision heater options for $20 or less. The
> original precision option was the Kuhne QH40A crystal heater, but I
> find Janilabs selling a similar product.
>
> <http://shop.kuhne-electronic.de/kuhne/en/shop/accessoires/crystal-heater/Precision+crystal+heater+40%C2%B0+QH40A/?card=724>
> <http://janielectronics.com/index.php?route=product/product&product_id=117>
> <http://www.setileague.org/askdr/xtaloven.htm>
>
> 73, Doug Reed, N0NAS.
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