"Ed Bailen" wrote in message
...
On Sat, 17 Apr 2004 02:55:43 GMT, "Z.Z." wrote:
Bill Brannick wrote:
.....
So.. if that telecoil can pick up RF from a cell phone, what is the
potential for it picking up RF from my own HF transmissions
here...(probably not all bands, but... )????
...

The telecoil doesn't really pick up RF from the phone.

The internal circuitry can pick up the RF as well and digital phones
*can* have a significant AM component. The coil wires can be simply like a
single wire picking up RF and feeding it inside the HA. When the TX is on,
RF is picked up and bias changes occur in some part of the circuit. When
the TX goes on-off, you have essentially square waves fed to the circuitry
at the pulse repitition frequency. Very small amounts of RF can be noticed
this way. The Nextel phone is the most noted since it has a distinctive
putt-putt (actually something like 10-20 HZ) which easily gets into computer
speaker amps.

Digital phones cycle on and off

As I said...

... The old analog phones didn't have that problem ...

This is because in "analog cellular" the transmitter was FM and on
continuously. It had no AM cmponent. If RF was getting into some device
you would not notice it until it got strong enough and changed the bias on
something to cause distortion or bias some circuit out of operating range.
Small amounts of constant RF wouldn't effect things enough to notice.


--
Steve N, K,9;d, c. i My email has no u's.