sundance-communications.com/forum Forums TDM Business Telephone Systems Panasonic Telephones & Systems RFI Problem

I am a homeowner with a KX-TD816 system; 4 KX--T7895 cordless, 6 KX-T7400 series corded, and 2 non-system single line phones. I have been having persistent probelms with RFI, mostly on the cordless phones but not exclusively, on which I pick up a local radio station (WOR-AM, 710KHz). The intereference is only audible in the house -- that is, the outside party can't hear it.

I have experimented with various ferrite cores, filters, etc. in various locations in an attempt to eliminate the RFI, but so far no luck. This weekend, I finally went down to the cellar with a buttset and after a long period of trila and error investigation, finally concluded that the KSU itself seemed to be picking up the interference. (I concluded that by the fact that I could not hear any RFI on the incoming Verizon lines,but when I connected to the extension output jacks on the KSU, I could hear the interference.

Any suggestions would be much appreciated. Thanks.

When you connected to the extension ports did you have ALL the other field wiring disconnected?
I'm willing to bet it's in the field wiring.
Disconnect all the wiring.
Use a butt set, (not just an SLT as the curly cord has a tendency to pick up RFI)
and see if you get the RFI.
Is the system grounded? If so remove it and see if the ground is inducing it to the system.
It's also possible that the AC power cord is inducing it to the system in which case you would need a good UPS with true AVR.
If you don't hear any RFI with all the CO and extension ports disconnected you can:
1: plug each extension in and see when you hear it or
2: check each extension port 1 at a time.
Tracking down RFI problems can be a long, tedious process but if you take it on step at a time I think you'll find the culprit.
I really doubt if the switch is pulling it in.

Good advice!

The other thing is that it can still be coming in on your telco lines. Its just being amplified by the system. remove the lines from the sytem and see if you still have it. If not you need to get the correct ferrtes for the frq. you have figured out. I have had real good luck with the ones from Mike the Sandman.

www.sandman.com

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