[HCDX]: Another Noise Source - Revisited

[w a merriman <merriman@xxxxxxxxxxxxxxxxxx>]

After sending my initial message yesterday I've done some more
experimenting with this unit.  First, some info about the unit
which someone asked for:

        Radio Shack Wireless Phone Jack System, 43-160
        States that it complies with Parts 15 & 68 of FCC rules
        FCC Reg Number:  AAOMLA-24509-RJ-N
        Also, whatever this means  REN: 0.7B
        Unit was made in Malaysia

Have done additional checking on the HF Amateur Bands and LW/MW.
As far as I can tell, the noise problem is limited to the 17 meter
Amateur Band with one minor exception.

This unit is being used with my computer modem.  When it is idle
with the modem not in use the only place I've found the noise so
far is on 17 meters.  At its strongest point the noise is about
S4 and extends about 8-10 kHz each side of the center frequency
gradually getting weaker until it disappears.  The center freq
is variable and a various times I've found it at 18085, 18075 and
18068-69 kHz.  It definitely moves around and is definitely coming
from the phone jack - it disappears when the jack is unplugged.

When I'm using the modem the nature of the noise changes.  It
goes from peaking about S4 and covering about 10 kHz each side of
the center to a low level crackling noise which barely moves the
S-meter but is now about 50 kHz wide - extending from around 18050
to 18100 kHz.  In addition, when the modem is in use I've found 
some very low level crackling noise on the 15 meter band above
21025 kHz and extending up to about 21100 kHz.  This noise is
definitely being caused by the wireless system because it is not
present when a regular phone line is used with the modem.  This
noise on 15 meters can be eliminated by using the noise blamker on
my Ten-Tec OMNI VI.  The noise blanker has very little or no effect
on the 17 meter band noise.

Have not checked the entire HF Spectrum so it is possible this noise
is occuring at other places on SW Brodacast, utility, etc. Also,
again, I ask if anyone has used another version of this and knows for
certain that it does not cause any problems I would like to know
what brand it is.  This wireless system looks so much better than
the previous phone line running across the middle of my house and
running a regular line over to the computer will be a problem.

73/DX

Al-K 4 G L U
Chincoteague Island, VA
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