[R-390] 200KC calibration crystal source

[Bob Camp]

Hi

The divider in the R390 is an injection locked multivibrator. It will  
only divide reliably at 50 KHz if you change some parts around.

Taking the 17 MHz crystal out of the oven is not going to help the  
stability of the radio much at all.

Bob


On Mar 29, 2007, at 2:16 PM, Phil M. wrote:

> I don't think this is exactly rocket science....but...
>
> Remove the oven.  Take the 17 mc xtal out of the oven and solder
> tube pins to it.  Insert this xtal in the socket so that it is between
> pins 4 and 6.  Take a common 100 kc calibrator xtal, solder tube pins
> to it, and insert it in the socket so that it is between pins 2 and 8.
> Now you can have markers at each 50 kc point as well as each 100 kc
> point.
>
> 73, Phil
> W5BVB
>
> ----- Original Message ----- From: "Perry Sandeen"  
> <sandeenpa at yahoo.com>
> To: <r-390 at mailman.qth.net>
> Sent: Thursday, March 29, 2007 12:20 PM
> Subject: [R-390] 200KC calibration crystal source
>
>
>> Gents,
>>
>> Wrote: 200KC calibration crystal source <snip>
>>
>> Perhaps a heretical solution is to build the marker generator in  
>> the ARRL handbook (which is
>> conveniently impossible to find rationally listed in the index).
>>
>> It has jumpers that allow the choice of several reference xtals or  
>> an input from a high stability
>> source.  Jumper selection can give a 200Khz signal.  I don't know  
>> if its amplitude can be used as
>> is or how one would couple it.  There is a PC board available.
>>
>> One advantage would be avoiding the 85C oven and its accelerating  
>> effects on aging.
>>
>> Regards,
>>
>> Perrier - Who almost successfully removed his left thumb top on a  
>> table saw cutting kindling wood.
>> Six stitches really spoils your day and my limited typing ability.
>>
>>
>>
>>
>> _____________________________________________________________________ 
>> _______________
>> Expecting? Get great news right away with email Auto-Check.
>> Try the Yahoo! Mail Beta.
>> http://advision.webevents.yahoo.com/mailbeta/newmail_tools.html
>> _____________________________________________________________
>> R-390 mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>> Help: http://mailman.qth.net/faq.htm
>> Post: mailto:R-390 at mailman.qth.net
>> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>
>
> _____________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:R-390 at mailman.qth.net
> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>