[Hammarlund] SP-600-JX-6

[Lee]

Sorry, but International Crystals is now Out of Business.  They closed 
there doors a few days ago never to return.

Lee, w0vt


On 4/24/2017 8:16 PM, Les Locklear wrote:
> ABOUT THE CRYSTALS
>
>  From Andy Moorer's website: http://www.jamminpower.com/main/sp600.html
>
> Scroll down to the bottom of the SP-600 notes and you'll find a handy calculator to use.
>
>
> I have had a number of questions about the crystals in the FCU (Frequency Control Unit) of the JX models. Getting a crystal is not a difficult process. International Crystals will be happy to sell you as many as you want, even in the antique HC-11 package, at about $15 each, custom-cut to your frequency. You do have to get the frequency right. It is not just the frequency of the station you are trying to receive. Here is a reduced version of the chart to figure out the crystal frequency, given the frequency of the desired station:
>
> To 7.4 MHz - add 0.455 MHz to get crystal frequency
> 7.4 MHz to 12.05 MHz - add 3.955 MHz
> 12.05 MHz to 44.05 MHz - Add 3.955 MHz and divide by 3 (3rd harmonic)
> 44.05 MHz to 54 MHz - Add 3.955 MHz and divide by 4 (4th harmonic)
>
>
> You will also have to specify some other stuff. Use the following:
>
> Case: HC-6/U
> Mode: PARALLEL
> Parallel capacitance: 40 pf
> Resistance at Resonance: 200-1000 ohms (not critical, as high as is reasonable)
> Mode: fundamental, 3rd or 4th harmonic from table above
> Precision: 25 ppm (you can get better by paying more)
> Signal Level: 2-5 volts.
>
> Les Locklear
>
> ----- Original Message -----
> From: <wb3fau55 at neo.rr.com>
> To: <hammarlund at mailman.qth.net>
> Sent: 4/24/2017 6:41:43 PM
> Subject: [Hammarlund] SP-600-JX-6
> ________________________________________________________________________________
>
> Folks, I got another question about the fixed freq operation.  As I can only guess,  how does one determine the freq of a crystal?  What I am asking is-  for a given freq,  below 7.4 mc,  do you add 455kc?  [or subtract?]  Then, above 7.4,  do you use 3.95 mc,  plus  or minus  the IF?  I know you folks know how to figure the xtal freq, for a given operating freq, so please enlighten me...tnx  Russ.
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