[RFI] RFI resistant telephones

Hare,Ed, W1RFI w1rfi@arrl.org
Mon, 2 Dec 2002 19:20:33 -0500

Hi, Ed,

Radio Shack has an extensive set of specifications their vendors have to meet.  Last I checked with RS, they require the phones to exhibit a modicum of immunity to RF fields.  That is why many of the RS phones have been somewhat RFI-resistant.

While not guaranteed against RFI, most of the time, when a customer returns a RS product, it is taken back with no questions asked.

Ed Hare, W1RFI
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Internet: w1rfi@arrl.org
Web: http://www.arrl.org/tis

> -----Original Message-----
> From: Edward F. Douglass [mailto:douglass@dcwis.com]
> Sent: Sunday, December 01, 2002 10:54 AM
> To: rfi@contesting.com
> Subject: [RFI] RFI resistant telephones
> 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 
> instrument.
> 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 
> model.
> 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
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