sundance-communications.com/forum Forums TDM Business Telephone Systems Panasonic Telephones & Systems radio interference

I have an old KXTD816 system and just replced telephones with KXT 7720 sets. Suddenly I have radio on intercom and outside lines. Does anybody have a good, simple, hopefully inexpensive solution for this? I have seen RFI filters for $20 to $25 but was hoping for something like adding a Capacitor somewhere. I have to do this for 7 phones.

Try ferrite coils they are cheap and available from any electronic parts place.

....or ground all unused pairs in the seven house wires.

The D816 should have had a ferrite coil on/for the power cord from the factory. Additional ones could be "clamped" on the 25 pair cable from the blocks to the KSU.

Check the KSU ground.

Just my thoughts.

Thanks for the replies.
It's been awhile since I chased an RFI problem thanks to Digital systems.
I remember some miracle devices called PORFFs that knocked down almost anything. You installed them inline with an analog pair.
I'm leaning towards the ferrite cores as this system didn't have the problem until I changed phones.
If that doesn't work i'll go after spare pairs and grounding.
It could be that either solution would work.
We'll see.

Well here's the outcome.
The Ferrite cores/chokes/coils did nothing, not on the handset cord, not on the cable NADA.

Grounding the KSU, ZIP.

Grounding extra pairs in the cables 95% reduction.
The good news is I collected the check!

KLD I owe you the Beverage of your choice, just drop by the SF bay area to collect! Heck if you make it here I'll throw in a Fine Dinner!

Now for the bonus round.. that last 5% of radio.

Many thanks

Jeff

Okay, let's see if my memory still works....the KXT7720 is analog and you are using it on a digital system....hmmmmmmmmmm....okay, flip the analog pairs (first two) at the 66 block. See if it works....if not, flip back.

When you checked the KSU ground, was it grounded to the same power ground as the electric for the KSU?

Did you put a choke of wire twisted around at least 5 feet of all the IW coming from the field prior to the 66 block? Use 16/14 ga ground wire and ground the bottom end tail.

Works like the aluminum foil to protect the KSU....

:rofl: :toothy:

PORFF. Man, been a long time, 12 years since I resorted to those! Got them at Graybar. I could see the AM tower from all the rooms on the backside of the motel, AND hear the broadcast perfectly well, more like conversation than background noise in the whole motel, every analog phone! BUT, the PORRFs worked, I put them on the backside of seperate 66M blocks and recut my X-connects! Try Graybar if all else fails. AS I recall they were close to $20 each.