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VK2YPZ > POWER 04.07.03 02:01l 41 Lines 1783 Bytes #999 (0) @ WW
BID : 390353VK2YPZ
Read: DB0FHN GUEST OE7FMI
Subj: Re: KB2VXA > Why fuse B- ?
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<VK6HGR<VK5UJ<VK5BRC<VK5ATB<VK2AAB<
VK2WI
Sent: 030703/1943Z @:VK2WI.#SYD.NSW.AUS.OC #:16462 [SYDNEY] FBB7 $:390353VK2YPZ
From: VK2YPZ@VK2WI.#SYD.NSW.AUS.OC
To : POWER@WW
Hi Warren and others,
Warren, I think you may have slightly misunderstood what I wrote. Or I did
not make myself clear enough, which is more likely.
The contractor did not reverse the battery polarity, he mistakenly
connected the Mobile phone power leads to the battery with their polarity
reversed (black lead to positive battery terminal, red lead to negative
battery terminal). The leads came with preinstalled tags to fit under the
clamping bolt on the battery connections.
The leads terminated in a 3 pin Cannon type plug. No problem yet, as the
plug is just lying loose. The transceiver fitted to a mounting bracket,
usually mounted in the boot (trunk) of the vehicle. It sat on rubber
blocks to stop any rattles, and didn't really provide a direct earth. The
only earth points were the negative (b-) power lead, and the shield of the
coax feed to the antenna. So once it was all assembled, we had a run of
"20 amp" dc cable from the Battery positive (front of vehicle) to the
transceiver (rear of vehicle). Then through the coax shield to the
vehicle's electrical ground. Once the Cannon plug for the power was
inserted into its recessed socket, you had to reach a bit to find the
release latch to get it out again.
We decided after this to make a simple polarity and load tester, so that
we could check the power supply before connecting it to our equipment.
We also decided that the negative/ground/B- fuse was a simple form of
protection against future problems with owners, service personnel, gas
station employees removing the leads while working on the vehicle and then
accidentally reversing them at reassembly.
73 - Kevin, VK2YPZ @ VK2WI
Message timed: 05:39 on 2003-Jul-04
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