Shanon,
I'm fwding this for info.
On Nov 27, 2009, at 5:19 PM, Allan Boyd ve3...@vianet.ca
mailto:ve3...@vianet.ca wrote:
Greetings Tony;
Well after reading your e-mail let me know you
are not alone with this problem with desense with
the Icom D-Star 2 meter repeater. Our D-Star
machine had the exact same problem when we first
put it on the air. We had a 4 can duplexer with a
high band pass cavity that was operating on a 60
watt analog repeater (GE Master II) with no
problem at all. Once we put the D-star machine up
on the same frequency same antenna and duplexer,
cables etc the only thing that changed was the
repeater was desense to the hilt. Tests showed we
had about 85 db isolation. Like you we tried many
things and troubleshooted everything else knowing
that the duplexers were good. After much head
scratching we finally learned through Icom rep
that the D-Star Icom IR-RP2000V needs at least a
minimum of 90db isolation and I say 90db at the
very least. We finally changed out the 4 can to a
6 can Sinclair res lock duplexer with a 100 db
isolation and all I can say is WOW what a
difference. The desense disappeared and the
D-Star repeater now way out preformed the analog
repeater we had up, it works amazingly because of
the extra isolation. As you are aware the front
ends of the Icom machine are not the best and
leave a lot to be desired we learned the rule
with this model repeater the more isolation you
have the better you are. It worked fine for the
analog system with the GE master II however once
we went digital we needed the new set of cans up from 4 to six.
Now I am not saying that this may be your problem
but by your e-mail it certainly sounded like my
complaint earlier in the year. Good luck.
73
Al
VE3AJB
Trustee VE3RXR Stack
Ontario Canada
At 01:26 PM 27/11/2009, Radioman wrote:
well to start with the outside signal is garbled up until i switch to
low then the user clears up, when switching back to hi he gets garbled
up again and when the user unkeys i here 2 seconds of robotic noise, and
the robotic noise does not happen on low.
i think that clear enough desense, with the tracking gen i have 86db of
isolation in the 4 pack cans
not perfect, but really not bad i also use a 10'' 3foot high band pass
cavity set to 1 db of loss and it gives me aprox
20db at 500khz window on my rx freqency
honestly i don't think you could ask for any better then that, but the
desense sounds like i have no duplexer's
and I'm starting to point at the poor construction of this over sized
empty box and shielding mobile radios give you
Tony
NN1D
