[amsat-bb] Re: swr-antenna question
domenico.i8cvs at tin.it
Mon Apr 14 02:43:03 PDT 2008
----- Original Message -----
From: <w0dxz at aol.com>
To: <amsat-bb at amsat.org>
Sent: Monday, April 14, 2008 6:53 AM
Subject: [amsat-bb] swr-antenna question
> Finally got my satellite antenna system set up, using with my IC-910H.
Works well on 144mhz, good PO, good SWR.?
> But on 432,,, I have good PO but NO reading on the SWR meter. As I tune up
and down the band, PO goes up and down, as I get? near or far from resonant
freq.? Power Out goes up and down as I tune up and down the band, but I get
NO reading on the SWR meter.? Using an older CushCraft 416TB, circular
right, I think.
> I expected either a good SWR reading,? (hopefully) or a bad reading, but I
get NO SWR reading. My only thought is how it is wired, for R circular. I am
hesitant to run much power until I determine the SWR.
> Any ideas as to why I get NO SWR rreading on 432 antnna? Seems to hear OK,
I can hear local repeaters, etc.
> Not sure what is going on. The meter is good, I checked that, SWR reads OK
on another? radio/antenna.
> Bob W0DXZ
> DM33 Sun City AZ
Hi Bob, W0DXZ
To test why you get NO SWR and if your SWR meter is good or not disconnect
the antenna from it and transmit a stady carrier with low power for two or
If your SWR meter is working properly you should read about the same level
for the forward power and the reflected power been the SWR very high and the
maximum possible without any load connected to it.
IF the above test is OK there are two possible outcomes.
1) The SWR of your antenna is very low and very close to 1 and so very good
2) The SWR of your antenna is greater than 1 and so no very good but your
instrument cannot read it correctly because your transmission line is
very lossy and the reflected power flowing back from to the antenna to
the SWR meter is partially dissipated in to the coax cable.
If you suspect that point 2) is the case then connect the meter directly to
the antenna connector on top of the antenna and now read the real reflected
power and the real SWR
I hope this helps
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