[amsat-bb] Looking for 8.8125 MHz xtal

Zach Metzinger zmetzing at pobox.com
Thu Jun 1 18:43:28 UTC 2017

On Thu, Jun 01, 2017 at 10:31:39AM -0700, Greg D wrote:
> Hi Zach,
> Whoa, your message raised a bunch of mental dust...  Is this for the
> infamous Drake 2880 downconverter?
> Perhaps as an alternative, the approach I took with mine was to not
> force the IF to be in the 2m ham band, but rather to center it in the
> Drake's original 200-400mhz passband. I would then use my ICOM IC-R7000
> all mode scanning receiver for the remainder of the RF chain.  A local
> oscillator frequency of 2100mhz put AO-40's 2401 mhz downlink at 301 mhz
> (easy math).  It ended up working reasonably well.
> Putting the IF outside the ham band gave me the flexibility to use
> either (any) ham band for the uplink, without worrying about
> interference. If you are looking to a future as-yet unknown bird, that
> might be a good idea.  If they use 2m for the uplink, using that for the
> IF as well is going to be a problem.  It also left (and used) the
> Drake's original passband filtering unmodified, improving the unit's
> performance.  In place of the ICOM receiver, I would now use an SDR
> Dongle, something not yet available back in the day.

Hello Greg,

Good guess, but not quite! This is a California Amplifier LNB that I picked
up when AO-40 started having problems, so I tossed it in a box and forgot
about it. Recent work has me digging back into those boxes and going down
rabbit holes long since forgotten about. :-)

Using an SDR or a general-coverage receiver is a good idea for fixed-base
work, but I don't have anything mobile that is general coverage. I do
appreciate the ideas!

--- Zach

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