[amsat-bb] Re: UHF antenna help
stanw1le at verizon.net
Tue Nov 30 04:54:35 PST 2010
Any terrestrial beacons on 432 MHz to listen to ?
The + vs. X configuration, no real advantages in satellite comms except
rain will wash off better with the X config.
X pol is X pol, no matter how you rotate the boom.
If you are planning terrestrial comms, consider the The + config since
most terrestrial comms are H polarization.
Have you got your pointing accuracy correct to true north ?
Any way to verify pointing accuracy, like with a terrestrial beacon ?
Have a friend go out with his TX and verify pointing accuracy.
On a rare occasion coax wears out intermittently, center pins can get
pulled back making poor contact.
Listening to a /B, wiggle the antenna and look for intermittent signals.
Are all coaxial connectors sealed from the weather ?
The VSWR at 1.5:1 is good, but not spectacular. What did you get before ?
Does the VSWR change as you wiggle the antenna ? Should be steady, no
matter where you look.
Does the az/el positioner work ? does it move ?
Stan, W1LE Cape Cod FN41sr
On 11/29/2010 8:14 PM, larry wrote:
> Good evening,
> Name here is Larry, N1MIW. I recently moved to a better (higher) QTH and
> finally got around to setting up the satellite station "almost" like it used
> to be, but am experiencing some reception difficulties on UHF. I'm hoping
> someone out here can help me diagnose what I'm doing wrong, or what the
> problem is. I am using a Yaesu FT-847 which is computer controlled, as well
> as the Yaesu G-5400 rotator. The antennas are mounted on a solid fiberglass
> mast only ~17 feet off the ground, and fed with LMR-400. The frequencies are
> correct for the satellite I want to use.
> My problem is with the 436CP30 antenna. I cannot seem to find good
> results with it since my move - terrestrial or sat related. My SWR is around
> 1.5:1 at 435MHz, and the polarity switch is working. I tried changing
> feedlines and removing the pre-amp, but I still cannot seem to make it work
> correctly. I am trying to receive SO-50 D/L, and VO-52 U/L, but both are
> just not working like I remember it being before the move. I don't have any
> broken or mis-aligned elements (that I noticed - I'll look again). The only
> thing I was looking into was instead of having it placed on the boom in a
> "+" pattern was making it an "x" pattern - would that make a difference? I
> don't remember hearing or reading about that anywhere, so I was looking for
> your opinion.
> On a side note, what's your opinion of this antenna? Like I said, I used
> to have good luck with it, but I'm not sure what's different, except the new
> home. Should I get "horizon" to "horizon" coverage (plus or minus a few
> degrees)? Oh, I also looped the coax off the back like the manual states,
> but the improvement is very minimal. I checked the "jumpers" at the tuning
> box, and they seem OK too.
> I'm running out of ideas, and any guidance would be appreciated. Thanks&
> looking forward to working the birds again!
> 73's... Larry N1MIW
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