CDM750 as crossband repeaters

[n8nm]

Hi,
I have several crossband repeaters (VHF in/UHF out) using '750s and RiCKs. I'm using these to link remote receive sites to a Digitac comparator (through more UHF 750s at the comparator site).

The system has been up and running for a few years, but there are a few lingering bugs that I haven't been able to resolve:

1) Squelch crashing. I've tried reverse burst and no burst, but the problem remains. I think it's due to the time constant being different based on received signal levels (dual level squelch). Anyone have any comments/suggestions?

2) I can't seem to get the audio level response to be linear, meaning that a given change at the flat audio input produces a corresponding change in deviation level. Ultimately, I'd like to get a +/- 4 kHz signal out of my transmitters when a +/- 4 kHz signal is on the input of the receivers. I can get it close, but then my PL level is waaay hot. I'm using CPS V6.01.00 and Tuner R02.05.00, using an HP 8920B and/or IFR Com 120B Comm monitors. Again, comments?

3) The PL decode in the receivers has a lot of trouble when the input signal contains a lot of content in the 400-700 Hz range. This is a ham system, and I have no control of how the subscriber units are set up. This causes some folks to "clip out" of the repeater while speaking. To get around this, I modified the RiCKs so that, once they get a valid PL Detect from the receivers, they only need to have a CSQ detect to keep the transmitter keyed and audio gated. Anyone else ever seen this?

Any suggestions are really appreciated!

-Steve Murphy, N8NM

[Ali Abbassi]

It will be far more reliable if you regenerate the PL at your link repeater , The SQ. crashing , if it means that SQ, gates opens while there is no carrier ,it needs to be tightened , the key here is to have high S/N at the RX input to produce full quieting , under this condition PL will be detected more reliably , and less noise will put on the TX modulation input, which in turn will produce a better S/N at the Comparator end , Some poor quality mobile and portabe radio ,not attenuatting the low side of the mic input properly, and this could cause PL canceling , chose a lower PL , to reduce this effect ,