Re: [amsat-bb] power supply for the down conv.--FREQUENCIES

[K5OE@xxxxxxx]

Art,
That is very consistant with my tests also (HP signal generator and monitor also).  An unmodified 3733 (after warm up) settled in at 35 kHz higher (2401.00 MHz = 123.035 MHz).  I also took another unit and replaced the 8.98 crystal with a 8.125 ICM (from N0NSV for a Drake) and found the conversion worked perfectly on MMDS compared to my Drake, but was also a little high in freq.  I could not get enough "spread" out of the little vari-cap to get it down to 2400.00 MHz = 144.00 MHz, so I settled for 144.100 MHz as being easy to remember.  This is just a plug-in crystal replacement!

I did some comparisons last weekend to my modified Drake 2880 and the TranSystem 3373 performs similarly on local ATV and MMDS.  I did not get a chance to try AO-40, but hope to get to it this weeekend.

Anyone that is interested in these downconverters can contact Bob at K5GNA@aol.com.  He has a "cute" little corner reflector that mounts right on the unit and makes for a nifty all-in-one hand-held S-band downconverter.  I plan to use one with my FT-100 for portable/mobile AO-40 mode U/S at the unmodified 123 MHz frequency.  
73,
Jerry, K5OE


Art Goldman <aegoldm@lts.ncsc.mil> writes:

<< Greg:

I found a "wall-wart" transformer that put out 18V. Actually, the unloaded
output was about 22V. I built a bias T in a small box with an F connector input
and N output. That way there's no possibility of mixing up the connections.

I just finished checking the 3733 on an HP sig generator and spectrum analyzer.
On mine, with an input of 2401.330 Mhz, I got the output at 123.380 Mhz. Just
for a reference, at 2400.00 Ghz, the output is at 122.06. At 2401.0 Ghz it's at
123.05. Gain couldn't be determined because I was using the bolt-on dipole that
comes with it. When I get my N adapter, I can be more precise.

Art, N3OY

greg wrote:

> well i have found a power supply that should work fine for the TranSsytems
> down conv. i had a old dss rcvr that has a power supply in it that has 18.6
> volts on it so that is what i amgoing to try i had the down conv. running in
> the shack with just a discone on it and after 30 min of operation the down
> conv. felt just warm to the touch i hope that is normal the power supply
> voltage with the load of the down conv. was around 16 volts
>
> GREG N8TDL
>
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--
 ---------
Art Goldman
Logicon Contractor
NSA Laboratory for Telecommunications Sciences
(301)688-1719


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