[NLRS] Crystals

[Zack Widup]

They are certainly worth a look but they are really hit-or-miss. Of the
four crystal frequencies I wanted to have within the past 6 months, Surplus
Sales had one. They are also of unknown characteristics if you need that
data. But the price is right!

73, Zack W9SZ


On Tue, Apr 10, 2018 at 10:54 PM, Dr. Gerald N. Johnson <geraldj at netins.net>
wrote:

>
>
> 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/c
>> rystal-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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