I suspect you my need "hardline" for that distance.
I have an interesting theory...
What if the length of coax actually were actually long enough for the tx signal
to remain on the wire while in RX mode? Probably need to be a mile long ;)
Another thought; anyone ever run seperate long cables from the TX and RX
cavities to the combiner (splitter) on the antenna side while the combiner was
close to the antenna?
|
TX cavity |||------------------coax-----O\ combiner |
\O----------------coax---------| Antenna
/ /|\
RX cavity |||-----------------coax------O/ /
\
73, KD6AAJ
--- On Wed, 10/1/08, Tom Elmore <[EMAIL PROTECTED]> wrote:
From: Tom Elmore <[EMAIL PROTECTED]>
Subject: [Repeater-Builder] LMR-400 Cable
To: Repeater-Builder@yahoogroups.com
Date: Wednesday, October 1, 2008, 10:06 AM
I recently put a six meter repeater (52.810/51.110) on the air here in
Anchorage, Alaska. I am feeding it with about 60 feet of LMR-400 cable and am
experiencing quite a bit of desense. I did a search for "LMR-400 in duplex
operation" and came across several posts from users of this list and decided to
sign up and investigate some more. I am running a GE Master Pro at 100 watts
into a 8 cavity Sinclair duplexer. The antenna is a Diamond co-linear mounted
about 35 feet above ground at the present time. I live on a hill here in town
and currently have the repeater mounted at my home qth. When I terminate the
duplexer into a dummy load and look at it with the spectrum analyzer it
performs very well with no desense. Connecting up the antenna is another story
altogether. I have been pulling my hair out over this one thinking it must be a
duplexer problem. Originally I fed the antenna with RG-213 which I know is not
the best choice for repeater use but it is
what I had handy at the time. I was getting desense with the RG-213 so I
switched to the LMR-400 since I had a roll someone had given me. I actually
think I had slightly less desense with the RG-213. Is the 400 really not that
suitable for duplex operation even at 6 meters? What would be a good alternate
choice ?
Thank You
Tom Elmore KA1NVZ
Anchorage, Alaska
