# Re: Drake frequencies

• Subject: Re: [amsat-bb] Drake frequencies
• From: "Edward R. Cole" <al7eb@xxxxxxxxxxxxx>
• Date: Wed, 14 Feb 2001 00:10:05 -0900

```Mark, and...

Look on the cover plate of your Drake.  Mine says Input: 2.5-2.686 GHz,
Output: 222-408 MHz.  So the LO is Fo-IF = 2278 MHz.  The xtal should be
2278/256 = 8.8984375 MHz.  If so, then 2.4 GHz would output 122 MHz exactly.

If on the other hand the xtal is Fx = 8.898430 MHz, then Fo = 2277.99808
and 2.4 GHz would be output at 122.001920 MHz.  Bingo!  That's what you
have, right?

I wonder if you are getting the 16th harmonic from your 150 MHz HT,
directly.  Or are you driving a diode?
Guess I should power up my unmodified Drake and Generate some 50 MHz RF and
look for the 48th harmonic.

Ain't math fun ;-)
Ed
And they gave me a BS in that subject back in the last millenium...figures
since I'm always BSing ;-)

>At 01:42 PM 2/13/2001, you wrote:
>>Floyd,
>>
>>The stock crystal frequency in the Drake 2880 MMDS converter is 8.89843
>>MHz.  The formula is:
>>
>>(2400 - X) / 256 = 8.89843; solving for X, I get 122.00192 MHz, if I've
>>got my sums right.
>
>Okay, I got curious.  I've read that for the stock Drake, 2400=120 MHz, and
>2400=122 MHz.
>
>So--which is it?
>
>I inspected my unit (from the group purchase..thanks, Mark :) and the stock
>crystal in mine is indeed 8.89843.
>
>After pointing my array into the shack, I used my HT to xmit on 150.01.  I
>heard the carrier at 122.152 +/-.  Assuming I am hearing 150.01 X 16
>(2400.16), this pretty much says for my unit, 2400=122 MHz with the stock
>crystal.
>
>And xmitting on 150.100 (x 16 = 2401.600), I can hear it on 123.589
(2401.589).
>
>I was incorrectly assuming 2400=120MHz this weekend; no wonder I couldn't
>hear it :)  Boy do I feel better now!
>
>73,
>
>
>
>
>
>Mark L. Hammond  [N8MH]
>
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