KE3HT mods/fixes
for problems I encountered with the
TS-64
01/03/2009
If you are going to do a repeater and want PL in AND out then the TS-64
is the way to go on a GE Mastr II!
I ran into a couple of problems setting up the local 147.03 repeater.
We have had it on the air without PL for 6 months. We had some
interference issues with a nearby Fire station AND I also wanted to
have a clean signal for IRLP. So I purchased another TS-64 from
Commspec. I have used this board 4 times before and felt it would be an
easy install. I also wanted to use the TS-64 to filter the incomming PL
as well as to produce output PL. So I wanted to use the TS-64 built in
filter. Since I wanted to have a nice chirp free signal for IRLP I also
wanted to use the TS-64 built in PTT delay to keep the tail "reverse
burst" from being heard.
I used some doc's I found on the repeater builders web site authored by
Doug
Sharp K2AD. He did a great job of documentiong the MOD. So these
two mods are in addition to the K2AD mod sheet.
I had two problems, #1 the CTCSS was not being noticed by the
controller (ARCOM RC-210) and #2 there was a ~500hz feed back loop.
#1 I tried flipping the controller active low/active high jumper but it
did not help. Both the controller and the TS-64 had open collector
actions but there was only 1.5v available so the controller could not
see the transistion after a built in diode. So I added a 10k resistor
between the 10v and PIN 5 on the TS-64 to let the open collectors work
properly. (See photo below)
#2 Audio feed back. For some reason there was a ~500hz audio feedback.
I could not see why so a quick fix was to put a small cap from the
input to ground (Pin 1 to Pin 9) to shead the feed back. I happed to
have a 100pf cap on my bench next to the slobering iron so I used that
for
now. A better fix is to pull the audio for the controller from pin 16
of J904 (RX PA) because it is already free of PL and it is flat
response. So no work to do!
All works well now and I thought others might want to find out what
they could do if they hit this problem.
Tim Ertl KE3HT
