[RFI] RFI resistant telephones

Edward F. Douglass douglass@dcwis.com
Sun, 01 Dec 2002 09:54:01 -0600

I am new to the list.  I have read the last few month's "traffic" but have 
not found a thread dealing with telephone RFI, and RFI-resistant telephones 
in particular.

As part of my diagnosis, I need an RFI-resistant telephone in order to 
determine if phone company equipment (lightning arrester, RF bypass 
capacitors, or other devices) are rectifying my transmit RF and putting 
audio on the phone line.

All of my phones are sensitive to RF because in spite of a variety of 
chokes and filters, I hear my SSB audio on every phone.  Some are less 
sensitive than others but they all have objectionable audio on them.  Of 
course, the audio could be coming from phone company equipment or faults in 
my phone wiring as well as my own phones.  If either of these happening, no 
amount of filtering or choking will solve the interference problem.

The ARRL RFI tech site mentions the Radio Shack ET-171 as a phone that is 
pretty resistant to RF.  However, my Radio Shack catalog no longer lists 
this model.

I am aware of the "bullet proof" phones from TCE Laboratories and Pro 
Distributors but they cost $80.  I would like to find a less expensive test 

Can anyone recommend a phone that I could buy at a WalMart, Target, Radio 
Shack store (or similar) that is RF resistant?  Please specify make and 

Or does someone have an RF resistant instrument that I could borrow for 
testing purposes?  I would be willing to pay shipping both ways.

Finally, has anyone found that re-wiring their residential phone system 
with Category 5e data cable has made a significant improvement in RF pickup 
to make the cost and effort worth while?

73 de Ed, AA9OZ