Message-ID: <0f0101c4fcda$38981ea0$7900a8c0@athlon1200>
From: "Dave Brown" <tractorb@ihug.co.nz>
To: rsgb_lf_group@blacksheep.org
References: <41EA3B2E.152.BF48D9@localhost> <000401c4fb13$98ef8180$f8ce28c3@erica> <003501c4fc11$e6b3c080$7c3f8351@w4o8m9> <J4hZn3qMsv6BFwdW@pickmere.demon.co.uk>
Date: Tue, 18 Jan 2005 10:19:25 +1300
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Subject: Re: LF: Re: SWR-off topic
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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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