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[RFI] 10m 24/7 "white noise hiss" RFI

To: rfi@contesting.com
Subject: [RFI] 10m 24/7 "white noise hiss" RFI
From: Patrick Dyer <pjdyer@swbell.net>
Date: Wed, 07 Nov 2007 15:21:05 -0600
List-post: <mailto:rfi@contesting.com>
At the suggestion of AE5B I'm posting this RFI situation here.
I've already had several responses from it on the W6YX VHF and WSVHF
reflectors - with suggested sources ranging from ubiquitous switching
PS's, internet CATV egress, etc.  In order to make a rational inquiry
of the likely operators of the source device I'd like to have as narrow
a list as practical vs just the "something in your house".
  This 24/7 10m white noise hiss on an FT-847 with a 3-el beam 20' AGL
peaks in the direction of the east-adjacent house.  My antenna base is
within c. 15' of the property line (the RF exposure with my 100w has
been calculated as being acceptable).  I  have also done a "sidewalk
proximity" check with an A-2586 (no s-meter) and a 27-MHz "rubber duck",
and it peaks in front of the same house.  Later using a 27-MHz loop it
also DF's to that house (perhaps to its near-mid section).

   On AM mode the hiss is 20 (or more) db over 9.  On FM the meter is
virtually pinned.  Using FM there appear relative nulls at apx 28.206,
312, 419, 526, 634, 743, 850, 959, 29.065 - that c. 100-kHz spacing may
strongly suggests that a superregen receiver of some sort might be the
source.  (In recent years I've mostly come across such RFI on 6-m due to
49.86 RC toys or HT's - but they are NOT 24/7 and were often very easily
"dealt with" by transmitting down very close to 50.000 MHz :>)

   However, later using an old CB xcvr on Ch 23 with an indoor magmount
antenna and listening with the Yaesu and Yagi it appeared to have no
effect on this RFI's strength or peak/valley freqs.

   This same source is also producing the characteristic "dotted slanted
line" RFI pattern on KCWX-2 (TL 50 mi nnw) and to a lesser extent on
WOAI-4 - all with a TV antenna located a similar distance from the
suspected source house.  They are on CATV so would not be able to detect
that effect (a "mixed blessing" of having non over-the-air TV viewers).
Also, such a small pattern is not too easily demo'd on a 5" b&w portable
TV screen.

   In 35+ years at this QTH chasing various RFI's it was likely far
easier to obtain source-user attention/cooperation when the sound was
clearly indicative of arcing/sparking (and the associated real/possible
fire hazards!) than for "just" a "white noise hiss".
   During this recent CQWW Phone Contest I had to resort to using my 3-e
15-m Yagi (aimed ne) to receive on 10-m and switching to the 3-el 10-m
Yagi to xmit!  (And hope that my Heath rotary coax switch would hold up
thru it all :>)

   If no quick resolution to this RFI is possible I am considering the
possible erection of another 10-m Yagi in a location more distant from
the source - but with these small 65'x120' lots that has its definite
limitations (and runs the real "risk" of it getting nearer to other
houses/RFI sources).

   73, Pat - WA5IYX  EL09ql

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