[RFI] GFI Outlets
jim at audiosystemsgroup.com
Sun Jul 25 12:36:10 EDT 2004
Here's a new one (for me, at least). I've always been a medium power guy --
100 watt barefoot radios have been my standard for 49 years -- but I recently
bought a Ten Tec Titan amp (legal limit out) to be ready for BPL. To check it
out, I've been loading it into some wire dipoles that are roughly 20 ft above my
A week ago, after I fired it up for the first time, a GFI in my upstairs bath died
(tripped, won't reset). I replaced it, and the replacement (same make/model)
died the next time I used the amp, during the IOTA contest this weekend.
Operation was on 40 and 20 meters. Mains power wiring is all inside grounded
steel conduit. There are also short cables of equipment plugged into the four
convenience outlets that are powered from that GFI. So you've got the RF on
these cables, and you have current induced on the conduit that can couple onto
the power wiring by SCIN (shield-current-induced noise).
The problematic GFI's are a Leviton model 802-6599W, and were purchased
at least 10 years ago. The replacement was a spare that was left over from the
original install. I took apart the first failed unit to find a pretty nice looking circuit
board (PNE-5) with what looks like either a transistor or SCR, an 8-pin
Motorola chip with an OEM number, five diodes, and a handful of caps and
resistors. I looked for shorts/opens on the diodes and the transistor, and found
none. There is discoloration of the circuit board around the only high power
resistor on the board. The color code looks like 1K, and I read 15K.
Is this a common problem with GFI's? Are there high spec units I can replace it
with? It's in a bathroom, so I don't want to leave the outlets unprotected.
Jim Brown K9YC
More information about the RFI