[amsat-bb] Re: S and L band suggestions
w7lrd at comcast.net
Tue May 25 01:11:50 PDT 2010
Hi Reid and those interested-
-Getting into L & S can be as simple or as complicated as one tries to make it. Many of us are using modified MMDS downconverters http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4GGLL_enUS379US379&q=mmds for what means.
The downconverter takes the 2.4ghz downlink and "usually" converts it to the 2M band. However usually for a 2M output the crystal and some minor filter modification is required. Generally if used without modification the output is around 123mhz. A downconverter can be had for as much as about $500 for the UEK-3000 or a Keps for about $225 or a surplus MMDS unit can be found on Ebay for as little as $5 (caveat emptor). For AO-51 in mode S (downlink) reception has been reported with a simple patch antenna connected directly to the DC. Or a simple 5 turn (left hand ci rcular polarization) in front of a 18 inch TV type dish will work well. Or a longer (10 turn +) RHCP helix can work. Again the DC is connected directly to the antenna/feed to reduce losses. Usually power for the DC is feed up the coax (RG6) to the DC from a bais tee(power inserter). A larger dish could be the 36"X30" primestar, from that now defunct direct TV system. They are usually free, just watch roof lines around your neighborhood. The bigger the dish the higher the gain and the necessity for accurate pointing. I use a Transystem 3731AA (MMDS) downconverter/5 turn helix feed/Primestar dish which is connected to an old TS-700A transceiver with Tx disabled to avoid that maj or ooops of accidently transmitting into the DC. For 1.2ghz (L band) uplink will usually cost some coin! Many "satellite" radios, like the IC-910, FT-736 etc. and several others can be had and adding the optional 1.2ghz module. Again not too cheap. Or a transverter. If in your area there is local L band terrestial activity, it can be quite interesti ng. L band antennas can be loopers, yagi's or a helix. I can get into AO51 quite well with 10W from an IC-910 to a 16 turn helix. I have some pictures available which can answer many questions. Good luck with your efforts. There are ma ny on this bb that have been doing this for a long time, and are wealth of information.
73 Bob W7LRD
----- Original Message -----
From: "Reid Crowe" <kc0idi at ku.edu>
To: amsat-bb at amsat.org
Sent: Monday, May 24, 2010 4:25:07 PM GMT -08:00 US/Canada Pacific
Subject: [amsat-bb] S and L band suggestions
I am thinking I want to get into S and L band operations. Does anyone
have any suggestions on getting started? What equipment is everyone using?
Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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