TenTec
[Top] [All Lists]

[TenTec] strange QRM/QRN/RFI source?

To: <tentec@contesting.com>
Subject: [TenTec] strange QRM/QRN/RFI source?
From: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Thu May 15 13:03:58 2003
There must be different varieties of incompatible X-10? I'm using the
simple plug in outlet controller (latching relay) and the simplest
controller.

Either the FT-736R is putting noise on the line or its line noise filter
bypasses the X-10 signal, but since the relay came on by itself during
the winter (its on an exhaust fan) while using the FT-736R, I suspect
its noise.

The local library uses X-10 for all their lights. Their electrician, in
a building update, installed a variable speed 3 phase fan motor drive.
They lost control of most of their lights for a couple months until they
could acquire and install a 30 or 40 amp three phase filter on the
variable frequency drive unit.

I did my graduate work on digital communications over the power line
(thinking very low speeds for control and meter reading and using the
spectrum near 60 Hz). I looked at noise levels in the spectrum I was
interested in. I concluded that its going to take a lot of power to make
anything fast work and then if its above ordinary power frequencies its
going to radiate as if connected to a dipole antenna. And that was
before the days of switching supplies and variable frequency drives. SCR
controlled induction heaters in one industrial neighborhood pegged my
noise meter.

Listening at 100 KHz is possible here, but any significant wire gets
plenty of signal from Loran C.

I have a better solution for the FT-736R. That's trading it off on
something with a receiver.

73, Jerry, K0CQ

-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
<Prev in Thread] Current Thread [Next in Thread>