I have one of these all-in-one units on my shelf here. The filter construction is *not* identical to the Cal-amp models, but you can use the same roadmap as in my article to figure out what is what. It will be a little trickier to get to work reasonably at 2401. This is because the input filter is a metal-ceramic (probably helical?) no-tune component that is soldered and glued to the board. The frequency range 2300-2700 MHz really depends on what it was designed for--some of the I understand some of the Austrailian models work at 2401 right out of the box, but the one I have (designed for MMDS service in the US) is probably 20-30dB down from its peak around 2500 MHz. The front end filter appears to be the bottleneck. Like other MMDS converters in the US, this one has a 2278MHz LO that gives you a 123 MHz IF for 2401.
Replacing that filter looks to be a bear, though it might be possible. If anyone has figured out how to do this without destroying the thin PC board, there would be many people interested. I imagine it would work acceptably for AO-51 if you just bypassed the font-end filter, but if you have any PCS stuff in the 2.1 GHz range you might have issues from the image frequency. I did that for my first S-band contacts with a Pacific Monolithics MMDS converter, using a horn antenna fashioned out of a large soup can it it worked fine from downtown Rochester, NY.
Andy K0SM/2
----- Original Message ----- From: "Michael Heim, KD0AR" kd0ar@sbcglobal.net To: amsat-bb@amsat.org Sent: Wednesday, May 5, 2010 7:36:51 AM Subject: [amsat-bb] Re: mmds downconverters for ao-51?
You will be astounded with the signal you will get from one of these downconverters. I used this modification: http://www.rvhfg.org/articles/k0sm/basic%20mods.php
________________________________ Michael Heim Chief Engineer, Forever Broadcasting New Castle PA WKST WJST WWGY 814-671-0666 Contract Engineer Cell: 330-502-6379 ARS KD0AR
________________________________
________________________________ From: "Gary "Joe" Mayfield" gary_mayfield@hotmail.com To: amsat-bb@amsat.org Sent: Wed, May 5, 2010 7:24:15 AM Subject: [amsat-bb] Re: mmds downconverters for ao-51?
Wow, the famous 'cigar' antenna. At that price you can afford to play with it.
73, Joe kk0sd
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of jfloyd@es.vccs.edu Sent: Tuesday, May 04, 2010 4:38 PM To: amsat-bb@amsat.org Subject: [amsat-bb] mmds downconverters for ao-51?
Has anyone tried one of the itfs mmds downconverters like this one on ebay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=110523087399&ssPa... TRK:MEWNX:IT
for ao-51 s band downlink? 75 ohm out and looks cheesey but less than $30 shipped. it's cheap enough for me to play so I bought one to experiment with, maybe just to remove the downconverter. I would welcome stories of your experience or just advice. Thanks John, kn4ge _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb