[TenTec] strange QRM/QRN/RFI source?

[Thomas Jednacz]

Hi Jerry, I have had several experiences with X-10. X-10 systems today are
more secure than they used to be but still not very immune to noise on the
power line. My guess is that the FT-736R is putting switching noise back on
the power line. You can build a filter or buy one that will block the
conducted noise. I was involved with electronic ballasts which is basically
a 100 watt switching high voltage power supply. We had to put substantial
filters in the product to keep the power line clean. One building used X-10
items and they would not work when the ballasts were installed. My
investigation showed that the X-10 had no protection against line noise and
worked on a simple ON/OFF power line carrier mode. Today's X-10 is much
better than that but still not very robust.

I think you have a receiver that will go down to 100 KHz. Take a piece of
wire and wrap it around the power cord to the FT-736 enough times to get
some coupling then listen around the 100 KHz area while switching the FT on
and off. If you hear any signal, get or build a power line filter. If you
build a filter, be sure to get capacitors that are rated for 120 volt lines.
They are called "X Caps" and are specifically designed for line filters.

73, Tom, W7QF

When my FT-736R is running on its internal switching supply, the X-10 in
my house won't run. One time the fan controlled by the X-10 came on from
the switching noise of the FT-736R.

As far as I know, X-10 controllers only transmit when there's a command
to be sent. They are quiet otherwise.

73, Jerry, K0CQ

--
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
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