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From: tad@ssc.UUCP (Tad Cook)
Newsgroups: comp.dcom.telecom
Subject: Re: Query: Cordless Portable Hand-free Telephone Set
Message-ID: <4737@accuvax.nwu.edu>
Date: 5 Mar 90 00:12:20 GMT
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X-Telecom-Digest: Volume 10, Issue 144, Message 6 of 10


Art Axelrod asked if there is a cordless portable headset type phone
that plugs into a regular POTS line.

I am using one at work.  It was made by Plantronics, then
discontinued.  I bought it from the DAK catalog.  It was cheap!

It works on the regular 46/49 MHz cordless phone frequencies.  My boss
and I got a pair on different channels, and hooked them up in parallel
with the phones on our PBX extensions.  The PBX is compatible with
regular POTS phones.

One thing to watch out for...computer RFI.  You may have to get some
ferrite beads and conductive paint to tone down the noise from PCs and
terminals in the area.

We find these very handy for roaming around the plant, so we can still
answer calls quickly.  It is very handy if I have to run down the hall
to look up something in a file.  I can keep talking to the customer
all the way.

Another handy use is just as a remote ringer.  Sometimes the RFI is
bad enough in the office that I can't have a really clear call when I
am a long distance away, but the ringer still works.  So on our ROLM
PBX, I just walk over to any extension and dial the call pickup code,
followed by my extension number.

I confess....being a ham I could not resist modifying mine.  The
antenna is typical for a cordless phone....short.  A quarter wave
groundplane seemed like a good idea.  A quarter wavelength antenna in
the 46/49 MHz region is about 5 feet (quarter wave at 46.8 MHz).  I
opened up the housing of the base unit, disconnected the external
antenna, and ran a five foot wire out that I taped vertically to the
wall (used the same color wire that matched the paint!).  Then I
located the ground plane on the circuit board, and attached an
external ground radial system.  These are also 1/4 wave (5 feet) long.

The base unit is on top of a metal file cabinet, next to the wall.  I
ran two radials, one in each direction, horizontally along the wall.
Then two more ran out at angles across the file cabinet, with the ends
taped down the opposite corners.  This gives good ground coupling to
the radial system, and makes for an efficient low-angle radiator.  It
also violates the FCC type acceptance.

The range on this is incredibly good.  The downside is that when the
secretary in the next office turns on her computer, which is located
directly on the other side of the wall from my base unit, it gets VERY
noisy, unless I am withing 60 feet or so.  The first day I had this
arrangement, I took a walk way out into the woods, lay down in the
sun, and took a few customer calls!

Remember that cordless phone calls are NOT private!

DAK still had the cordless LiteSet in their latest catalog.

Have fun!


Tad
tad@ssc.UUCP
 ...uw-beaver!amc-gw!ssc!tad