[R-390] RE: Ovens

[Bob Camp]

Hi

The calibrator crystal would be a bit tough to do as a "stable at room 
temperature part". The 200 KHz  frequency is low enough that you can 
not do it as an AT cut in that holder. The HR202 oven is actually a 
pretty good little unit. It will hold a couple degrees during fairly 
major external changes. Since it's a plug in it's easy to replace if it 
runs away. It's not all that different than the units you wold see in 
the older two way radio sets.

One interesting thing you could do would be to replace the first LO 
crystal with a room temperature unit and then replace the calibrator 
crystal with a cell phone TCXO and a digital divider. You would have a 
more accurate calibrator. What ever you did would fall into the 
category of easily reversible modification if it was all in a 
replacement oven plugin. Next step up would be to phase lock the first 
LO to the TCXO.....

As you pointed out "why spend the extra money".

	Take Care!

		Bob Camp
		KB8TQ



On Aug 9, 2004, at 11:26 AM, Laird Tom N wrote:

>> From all that I have read over the years, I agree; don't use the oven.
> For the semi-purest. You can buy crystals for HR202 from mhelectronics
> that are designed for room temp. Although, the consensus is "why spend
> the extra money".....
>
> Tom Laird WC9M
> Moline, IL.
>
> -----Original Message-----
>
> My 3 cents
> Don't use the ovens period!
>
> Les  Locklear
>
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