Hi Bruce, My "rf source" is actually the mode V/S adapter described by Tony, AA2TX in the Sept./Oct. 2005 AMSAT journal. It's actual purpose is to convert the 123Mhz IF of the downconverter to 6 meters thereby freeing up my two meter antenna jack for mode V/S. On a suggestion from Tony, I hooked the downconverter up to my HT and then powered up the V/S adapter seperately and listened for a 2415 Ghz. harmonic from it. I found it at about 137.025 Mhz. on the HT as Tony said I would. I have no idea as to the signal strength of this harmonic. There was no antenna attached to the V/S adapter. Of course you said there was no antenna to speak of on your signal source either so it's puzzling. One thing is certain, I've got a bum right arm right now and I'm tired of raising and lowering the dang mast! Everything sits atop a 30 ft. mast. I t gives my antennas a better "view" above the tree line and also gets them above a dogwood tree that my XYL refuses to let me cut down. They won't rotate otherwise. 73, Michael, W4HIJ Bruce Robertson wrote:
Quoting Michael Tondee mat_62@netcommander.com:
I have tried all week to be able to hear the S-band downlink with a BBQ
grill dish and AIDC 3731 converter. I checked aim of my antennas and can
receive a signal when a signal source is hanging off the dish but no joy
as far as hearing the bird itself. I don't have an antenna for L band yet so I can't transmit. I'm very discouraged and about ready to yank the dish/downconverter off
the mast and give up. 73, Michael, W4HIJ
I would yank them off the mast, but not give up. Others have suggested that the beam width of the setup you describe is quite narrow and might be requiring better pointing than you have right now. Here's a procedure to see what's what.
I have one of the self-modified CalAmp $6 units It works much better hand-held than on the mast, and I have just a 8 dBi gain patch antenna on it. On future S-band opportunities, I would try pointing the d/c by hand with its feed alone, no dish, and see if that works. If you can hear something, then I'd say there's a pointing issue. (For the sake of comparison, I can hear part of a 20-30 deg. max el. pass through a window. Not good copy, but enough to prove things are tickety-boo while the snow is flying.)
If you can't hear anything at all by this means, I wonder if your d/c is sensitive enough. It worries me that your rf source has to be 'hanging off the dish'. I have an rf source like the one described in the latest Amsat Journal, but with no antenna to speak of. I can still hear it as a weak signal indoors through a window about 15' from the antenna when the rotor is vaguely pointing my way. When I first was working on the d/c and hadn't peaked the filter, the source had to be no more than an inch or two from the d/c. At this point, the d/c wouldn't receive Echo.
Steve, WI2W, gave me some excellent advice, which I think should be shared with others. Noting that our CalAmp $6 d/c's were a bit marginal, he recommended that instead of building a more narrow beamwidth antenna, I should get a mast-installed preamp for 2.4 gig. The plan is to keep my broad-beam antenna (which is better for the LEO situation) and improve my gain and noise floor with the preamp. SSB USA has them for $125ish. His is the sensible plan if one's goal is a easy-to-use LEO s band setup. I'm interested in building antennas and such, so I'm working on a 15 turn helix and adding elevation control to my rotor. But by the time P3E and ESEO fly, I think the preamp will be necessary.
Maybe the next time Echo is transmitting on S band, we'll both have working systems!
73, Bruce VE9QRP