The SWR measuring trolley was a standard piece of kit at multi-tx HF
transmitter sites with multiple openwire antennas and feeders. Keep in
mind the real estate involved was large, very large, and when doing
feeder maintenance out in the field (literally!) no way were you able
to keep referring back to an instrument in the transmitter hall -
often several hundred yards away. I have one of these units that has
not found it's way to the Telecom NZ museum as yet, and a few photos
are at
http://homepages.ihug.co.nz/~tractorb/swr%20trolley/
There are two separate loops in this incarnation and the loop
switching, at the top of the separate handheld meterbox, allows
selection of either loop or both in series, to drive the meter
circuit. A meter sensitivity switch is just below the meter and tuning
controls to select the appropriate frequency are lower down the
meterbox.
The unit was moved along the feeder (typically around six to eight
feet off the ground on short poles) by an insulated handle with the
wheels riding on the top of the feeder wires. There is a locking
arrangement comprising two tufnol slotted blocks near the centre of
the unit-they can be moved in and out with a lever. The blocks are
moved in to pass the open wire conductors over the top of them when
placing the carriange wheels on the transmission line and then lock in
the outer position to prevent the carriage from lifting off.
73, Dave, ZL3FJ
.
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