On Fri, 12 Nov 2004 04:55:12 GMT, "Joel" wrote:

Anyone else have trouble with HF - tripping GFCI in my garage when keying
the mike.

I don't have trouble with HF tripping the GFCI in YOUR garage, but I sure as
hell have a similar problem here in my shack.

Cheap shots aside, the GFCI usually contains a toroidal core which has the
active and neutral (return) lines pass through it, and a secondary winding which
sees the difference between the active and neutral currents i.e. the current
passing through another route (ground assumed). The secondary feeds an
amplifier which drives the trip circuit.

In an endeavour to obtain decent sensitivity AND fast reponse, there appears to
be a general lack of RF immunity in these devices.

If I use a VHF handheld within a metre or so of appliances connected via the
GFCI, no problem. However if I use the same device sitting in its mains-powered
charger base - on or off charge - the interrupter trips. I also have a 25W
transceiver on 80 MHz (commercial) which caused frequent tripping on Tx until I
took remedial measures.

presumption mode Enough RF is conducted along the power lead to result in RF
in the toroid's secondary which the amplifier rectifies/detects. /presumption
mode

In the case of the 80 MHz set, I slipped a toroid over the DC power lead. (RF
choke). DC power is derived from a mains PSU. Antenna is not earthed to this
system. Problem gone.

In your instance, it may be RF entering by direct radiation from the antenna
into the GFCI or power cables passing through same, OR it may be RF getting
conducted back up the supply of the HF set. Trial and error should determine
which - does it trip when you run the Tx into a dummy load? Can you try a
toroid around the supply cable?