CDM RPEATER PROBLEMS

[JD]

I have a CDR 700 repeater on 469.5/464.5. Checks out fine on the bench, get it in the field terrible reception, not even line of site.
I have tried 2 different feed lines, lmr 400 at 60 to 100 ft. and 2 new RFS PD 201 UHF base antennas.

Might there be an issue with the frequencies and CDM700 raidos ??

Thanks.

[Al]

How closely and how are your antennas mounted with respect to each other? Sounds like receiver desense may be the cause of your problem.

[JD]

No other antennas within a few miles. I thought it might be the cable and or antennas. I think you are on the right track. I am going to try another repeater. The company brought the repeater with them, said it did not work very well at the last site.

[Jim202]

What is being used for the duplexer? Has the tunning of it been checked recently?

Has the receiver been put on a service monitor to see just what type of sensitivity it has?

I would start looking at the radio equipment long before I play with antennas. Need to make
sure it works before going any further.

Jim

I have a CDR 700 repeater on 469.5/464.5. Checks out fine on the bench, get it in the field terrible reception, not even line of site.
I have tried 2 different feed lines, lmr 400 at 60 to 100 ft. and 2 new RFS PD 201 UHF base antennas.

Might there be an issue with the frequencies and CDM700 raidos ??

Thanks.

[JD]

In the field, the receiver has very good sensitivity, was not able to check on duplex. I have set up another antenna about 1.5 miles away, in line of site. Thanks for the info. I will post results here.

[HumHead]

If I am reading your post correctly, it sounds like you are using separate antennas for the transmit and receive radios in the repeater.

That being the case, it sounds like you have not provided adequate isolation, and your transmitter is desensitizing your receiver.

You need to either have a properly tuned duplexer feeding one antenna, or you need to install your two separate antennas in a directly co-linear arrangement with at least 15 - 20 feet of vertical separation between them.

[RKG]

I have the same sense as Humhead.

Try this test:

With system set up exactly as used in the field, turn off the Tx radio and have a subscriber transmit in on the input. If the Rx radio hears him LC, you have a desense problem.

[JD]

That is what I will do. I took a HP8920 out and could see nothing on the input frequency. I tried another repeater nad had the same issue. I think the cable and or antenna has a problem. Installer said the cable got loose and put a severe tug on the connection.
Thanks for the input.