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. Digital phones
cycle on and off in the audio range (teens of kHz) and it's the hash from
the switching that the coils pick up. They're optimized for a fairly
narrow freq range to match the passband of telephones. The old analog
phones didn't have that problem (at least I never noticed it) on the same
freqs and usually with migher power than the digital phones. I've never
noticed any problems with RF in the HA's but the telecoils are sensitive
to other fields, esp. from computer monitors or any other audio freq
emitter (TV's, transformers, flourescent lights, some of those anti-theft
thingies they have in stores that you have to walk thru, etc.).). I
suppose if you worked really, really LF (20kHz) you might have some
issues but even then only when the coils are switched in (they're not
active all the time...you have to switch them on). Actually, the cell
phone I have now (Motorola) works fine without the telecoil, it's just
kinda touchy where you have it positioned...you gotta get the phone
speaker lined up with the mic on the HA. Also, Moto and Nokia make loop
adapters that you wear around your neck and plug into the phone and
couple with the telecoil...they work pretty well and get the phone away
from the HA and make it kind of hands-free (I suppose they'd work with a
radio if you wired up a little adapter...hmmm.....).

Be patient with your new HA's...you'll be overwhelmed with sound for a
while...stuff you haven't heard for a long time. It takes a while to re-
adjust. The world is a lot noisier place than you remember :-) It'll
take a few visits to the audiologist to get them set up so be prepared to
work with him/her. And if you're getting digitals, look into the noise
reduction capabilities...it'll make the bands a little quieter...

Good luck...

73... Mark AA7TA

The noise generation from the power supply is more of an issue with
GSM and TDMA technologies. The GSM/TDMA handset transmits 217 bursts
of data per second, so the switching power supply has to ramp up for
the transmitter 217 times a second. The 217 Hz noise is more
noticeable when the handset is located far from the cell tower and the
transmitter is pumping out maximum power. CDMA does not pulse the
transmitter and, therefore, should not have the buzzing problem.

Regards,
Ed Bailen - N5KZW

"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.

"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.

"Bill Brannick" wrote in message
...
As another confirming moment in my life, next week I will be fitted
for hearing aids.

My wife wears a HA and had no trouble using her older Cellphone, even the
new one worked FB until the local systems switched to Digital Service. If
she uses it in the country-side where it is still Analog Service there is no
problem !

The problem is- in the city, all new Cellphones automatically default
to the Digital Mode !

The only answer available is to revert to using an analog service only
Cellphone! Thank God for EBay

I think the only real solution is somewhat similar to TTY for the deaf
.. Legislation ,mandating the availability of an ANALOG service channel on
all Cell-nets as a Legacy Mode for the Hard of hearing . Apparently there
is no simple solution to the Envelope Modulation interference caused to
Hearing-Aids by the Digital Mode of Operation. It would be relatively
simple to require the owner of the Analog-Mode Cell-phone to show a hearing
aid at the time the phone is activated, a procedure that requires the
presensce of the obsolete analog Cell-phone and presumed operator to
interact with a representative of the Cellphone Network.

The operators of the Cellphone Networks would love to eliminate the
bandwidth hogging Analog Channels, but there seems no simple solution .
Inductive Neckloops seem a sloppy solution to a technicalogic problem..

Digital Cellphones and Digital service are NOT compatable with Hearing
Aids!

Yukio YANO

VE5YS

"Bill Brannick" wrote in message
...
As another confirming moment in my life, next week I will be fitted
for hearing aids.

My wife wears a HA and had no trouble using her older Cellphone, even the
new one worked FB until the local systems switched to Digital Service. If
she uses it in the country-side where it is still Analog Service there is no
problem !

The problem is- in the city, all new Cellphones automatically default
to the Digital Mode !

The only answer available is to revert to using an analog service only
Cellphone! Thank God for EBay

I think the only real solution is somewhat similar to TTY for the deaf
.. Legislation ,mandating the availability of an ANALOG service channel on
all Cell-nets as a Legacy Mode for the Hard of hearing . Apparently there
is no simple solution to the Envelope Modulation interference caused to
Hearing-Aids by the Digital Mode of Operation. It would be relatively
simple to require the owner of the Analog-Mode Cell-phone to show a hearing
aid at the time the phone is activated, a procedure that requires the
presensce of the obsolete analog Cell-phone and presumed operator to
interact with a representative of the Cellphone Network.

The operators of the Cellphone Networks would love to eliminate the
bandwidth hogging Analog Channels, but there seems no simple solution .
Inductive Neckloops seem a sloppy solution to a technicalogic problem..

Digital Cellphones and Digital service are NOT compatable with Hearing
Aids!

Yukio YANO

VE5YS