Repeater

[Ron865]

I'm running Motorola CDM 1250 40 watts, with a ID- O- Matic IV , Motorola 400HMz to 500z duplexer and LMR 400 coax with Comet CA 712 EFC antenna. My TX side is clear as a bell but my Rx side is weak with white noise in the back ground. the duplexer is tuned to -93db, and everything was tune and programed by Motorola techs. 

[gortex2]

What cables between the CDM1250 and the second CDM1250 and duplexer ? How long is the LMR400 ? What is the Watt meter show on the antenna side ? Where do you hear the white noise ? On the RX radio ? 

[jonesm0]

Some years ago, we found LMR feed line could be "noisy" in the UHF spectrum, fought it over a year, replaced with Belden 9913 and problem poofed....

[Cactusboy19]

On 12/30/2022 at 9:26 PM, jonesm0 said:

Some years ago, we found LMR feed line could be "noisy" in the UHF spectrum, fought it over a year, replaced with Belden 9913 and problem poofed....

This is good for duplex? I am also looking for new feed line for my repeater. I have LMR 400 and also experiencing noise.

[gortex2]

The noise issue in in duplex applications. It has been discussed many times. Its worse if any water gets in it or the connectors. If your running a repeater fine a variant of LDF and it will resolve the noise issues and have better loss.