[R-390] 200 kHz Crystal

[Bob Camp]

Hi

The ceramic resonators normally have a frequency tolerance of a few 
tenths of a percent. Their temperature stability is in the same range 
for most "mixes" of powder. In both cases these numbers are tens to a 
few hundred times worse than a typical crystal. They work fine for some 
things like simple computer clock sources but do not do as well for 
frequency standards.

	Take Care!

		Bob Camp
		KB8TQ

On Feb 20, 2005, at 10:40 PM, Michael Murphy wrote:

> Bob,
>
> Ocean State lists a ceramic resonator for 200 kHz for $1.39. This may 
> not
> oscillate without exploding  but it sure would make an interesting
> foundation for a plug-in solid state calibrator source for the 390A. 
> No idea
> if it would be stable over temp, but if it were kept at a constant 
> temp, it
> may work.
>
> http://www.oselectronics.com/ose_p68.htm
>
> Blip Blip Mike Murphy WB2UID
>
>
> ----- Original Message -----
> From: "Bob Camp" <ham at cq.nu>
> To: "Mark Huss" <mhuss1 at bellatlantic.net>
> Cc: <R-390 at mailman.qth.net>
> Sent: Monday, February 21, 2005 10:11 PM
> Subject: Re: [R-390] 200 kHz Crystal
>
>
>> Hi
>>
>> The 17 MHz crystals are still made and relatively easy to find. It's
>> the 200 KHz crystals that are a problem. The radio is in big trouble
>> with no 17 MHz crystal. Without a 200 KHz crystal it still limps along
>> with no calibrator.
>>
>> Stuffing a 100 KHz crystal into the 200KHz position might work with
>> minor circuit modification. I am not sure that helps since all of the
>> old crystals below 500KHz are pretty darn tough to find. There are
>> people who make them but the cost is staggering.
>>
>> The simplest replacement probably is a (yikes!) solid state divider
>> tacked on to a cell phone TCXO. In order to switch it on and off you
>> probably would have to do at least one solder junction inside the
>> radio.
>>
>> Take Care!
>>
>> Bob Camp
>> KB8TQ
>>
>>
>> On Feb 21, 2005, at 7:15 PM, Mark Huss wrote:
>>
>>> Still looking for a 200 khz crystal for the Calibrator.  Fair Radio 
>>> is
>>> out
>>> of stock.  I hear that since the heater for the 200 kHz and 17 MHz
>>> crystals
>>> are always on, that the life of these is limited.  Is anyone
>>> interested in
>>> developing a frequency doubler for a standard 8.5 MHz crystal to
>>> replace the
>>> unobtainium 17 MHz crystal?
>>>
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>