[amsat-bb] Re: Antenna Problem ..need some help please
racer5039 at q.com
Sat Jul 18 21:11:43 PDT 2009
Yes, It is CP. and I do have the mounted in an X to the cross boom.
When I made it last yr, I'm not sure that the gama match's are set the best that they could be.
I have 60" of 1/2 hard line to a T then 2 pcs of 75 ohm coax to the antenna. Works ok on RX but I think it could do better on TX.
I have pre amps on my X-mas list :)
----- Original Message -----
From: Greg D.
To: racer5039 at q.com ; amsat-bb at amsat.org
Sent: Saturday, July 18, 2009 11:05 PM
Subject: RE: [amsat-bb] Antenna Problem ..need some help please
If the SWR suddenly changed, you've probably got a broken feed wire somewhere. I'd leave the matching section adjustment alone (assuming it was good before), and focus on the connections, starting at the shack end.
It sounds like you have a circularly polarized antenna, in which case it doesn't matter which set of elements are horizontal. In fact, many mount CP antennas in an "X" orientation to minimize the interaction with the supporting boom.
If you want to make adjustments with the antenna off the tower, I find it's best to point it straight into the air to minimize the effects of being near the ground.
Good luck with the debugging,
> From: racer5039 at q.com
> To: amsat-bb at amsat.org
> Date: Sat, 18 Jul 2009 22:53:15 -0500
> Subject: [amsat-bb] Antenna Problem ..need some help please
> I am having a problem with my home made Beam for 435/437. This may/June the SWR went to 5+
> I'm going to get it down and take a look at all the connections and to gama match's.
> What is the best way to set the gama match's? I have access to an MFJ 269 for adjustments.
> Also what set of elements should be forward ? They are offset by 1/2 wave. Should the vert or horz. be the forward set? Make any difference?
> Also my ts 2000 went down just before field day and needs to go in been quiet around here for too long.
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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