Happy New Years to all to start with.
I have a 2 meter repeater that uses one of the older Sinclair 202-g
duplexers. I think this is the right model number...its the 4 can
hybrid ring model with the horizontal notch dielectric tuning stubs n
top.
As one can expect, I'm getting about 70 dB or so isolation from the
system and needless to say, I've got my share of desense. Just out of
curiosity, I checked a single DB-4044 can on the spectrum analyzer
tuned to my repeater output frequency...146.775. Despite the specs
for the duplexer as a whole indicating a frequency range of 148 to 174
MHz, I was able to tune the can to obtain about 20 dB of attenuation
with a .5 dB insertion loss setting. The repeater is a MSR-2000 with
the intermittant PA set at about 60 watts. I do have the factory pre-
amp installed.
Obviously, I'm looking to try to use these DB-4044 cans to increase my
isolation. Even tho the cans show "useable" on the spectrum analyzer,
in real life, is this a viable solution? My thoughts are to use 2 or
3 cans on the receive side and 1 or 2 cans on the transmit side
installed between the Sinclair duplexer and the repeater.
I have this duplexer just sitting around collecting dust and I thought
I would try to put it to some use. If the "plan" would work, should
I...
1. leave the insertion loss as it is at .5 dB per can or increase
it in order to achieve a bit more attenuation?
2. do the 3 plus 1 install or the 2 plus 2 or are extra cans on
the transmit side even necessary
3. are cable lengths between the DB-4044 cans critical and are
the cable lengths between the last DB-4044 can the the first Sinclair
can critical? I'm assuming that the cable lengths between the
repeater and the first DB-4044 can on each side are not critical, as
normally is the case...correct me if I'm wrong (on any of this).
My repeater site is at a low noise area if this is relevent.
Thanks for the in advance for any info and everyone be safe and Happy
New Year!
Bob, Rowan County, NC ARES EC, GMRS WPVV845, Amateur KG4WAD, LMRS
WPXC892
