[RFI] MOBILE RFI KILLS ENGINE of 1998 Rodeo
Dave Jordan <email@example.com>
Sat, 03 Jul 1999 00:13:11 -0400
I just finished installing a Yaesu FT-900 in my truck. The transceiver
is located in the rear of the vehicle with the remote head up by the
front console. The power leads run directly from the battery down the
frame (outside the vehicle) back to the rear fender and enter through
the rear fender. The antenna is a screwdriver antenna mounted on the
trailer hitch. I use 3/4inch copper braid strap to connect from the
base of the antenna to the frame, from the transceiver to the frame,
from the negative battery terminal to the frame.
On 40 m the keyless entry system continuously activates on SSB mode. I
pulled the control board and it was fed with 22 control wires. Quite a
bundle. On the board were more than a dozen diodes and zener diodes, no
control wires were bypassed, nor where the diodes by-passed. I placed
.01 ceramic capacitors across all the control wires and diodes and the
problem has been resolved
(at least for 100watt operations). However, on 75m SSB one work kills
the engine. I have not
solved this problem. However I did discover by accident that there is
significant RF on the control
cable running from the transceiver to the control head of the FT-900.
While testing on 75 I got an
RF burn from the ground side of the speaker output on the back of the
FT-900 remote control head. Somehow the control cable is picking up all
kinds of RF. WHen I ground the control head speaker ground the receive
audio is now unindated with alternator whine.
Even though the antenna is matched and resonated it appears there is
significant RF on the control cable. Tomorrow I will install an RF
isolator on the coax feed to the FT-900 transceiver.
I will also install a brute force line filter on the power leads in an
effort to reduce RF from entering
the control cable. Third I will re-route the control cable as I've
discovered the cable runs very close
to the main engine computer which may be the reason the engine stalls.
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