[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

KLM 2M-22C antenna

Hi all,
    About 8 months ago I bought used a KLM 2M-22C (22 element CP 2M
antenna) and the matching 430 antenna for satellite operation.  They
have for the most part worked quite well.  I have however been plagued
with intermittent high SWR problems (and poor performance) from the 2M
antenna.  In the past, I have been able to fix it by taking all the
cable connections apart in the feed system between the SO-239 connector
and the folded dipole feedpoints on the two antennas.  Cleaning up the
corrosion from the connections seems to have gotten it working in the
    A week ago I noticed the SWR was back up again and verified the
problem was with the antenna, and not my coax cable.  I finally had a
chance to do the usual take it all apart and clean all the connections
and it did not help at all this time.  When measuring the SWR at the
antenna system, I am getting about 70% reflected power (measured with a
Bird 43).  I hooked up the feed to each antenna half separately and each
measured about a 6:1 SWR - which seems about right since the the
antennas are 300 ohm feed folded dipoles.  Since they were the same, I
don't think there is anything wrong with one of the antennas halves.
Besides there is not much that can go wrong with a simple folded dipole.

    When I had everything apart I checked for proper operation of the
polority switching relay and coax phasing harnesses (visually and with
an ohm meter).  Since the antenna halves are OK (I think), the only
thing left is the thingie that has the SO-239 on one end and 2 pieces of
RGU-303 coming out the other.  I assume that is a splitter and / or
impedence transformer.  Since KLM is out of business, it's a little hard
to ask them.  Since I don't know exactly what's in that little pipe, I
can't tell for sure what it's supposed act like when tested.  Does
anyone know really what's in there and what results I should get when
testing it?
    One of my options is to scrap the KLM polarity switching and employ
a switching scheme that will allow H, V, LHCP, and RHCP with the two
antennas.  However, for at least the time being, I would like to get the
KLM switching/feed working.  Any suggestions?

Jim Walls - K6CCC
626-302-8515    FAX  626-302-9999

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org