Thread: 4NEC2?
View Single Post
  #37   Report Post  
Old October 14th 18, 07:49 PM posted to,
Jeff Liebermann[_2_] Jeff Liebermann[_2_] is offline
external usenet poster
First recorded activity by RadioBanter: Jun 2007
Posts: 1,332
Default 4NEC2?

On Sun, 14 Oct 2018 13:39:38 -0400, Ralph Mowery

I don't know anything about the tractor trailer wiring, but around 1972
I picked up extra money repairing the CB radios. Several truckers
brought in rigs that were blown up when switching from the car to the
truck. None of them had a fuse in the negative power lead. By blown
up, most had a diode across the poer wires inside the transceiver and
that diode had shorted and blew the fuse. I seem to remember then they
talked about the tractor haveing a positive ground. Probably ran on 24
volts also.

I installed a few radios in White Freightliner tractors in the 1960's.
They were all positive ground 12V. I think they switch to negative
ground in about 1975. Many other older tractors were positive ground
but switched to negative ground in about 1954-56. I vaguely recall
conversion kits being sold at the time.

I've seen a few 24V electrical systems, but those were all in military

I have only ran FM ham rigs in a car. I used to ground the rig to the
frame and run the positive to a relay that comes on when the car is
started. Never had any alternator whine or problems. For about the
last 10 or more years I just plug into the lighter or accessory socket
in the car. My Toyota power on those sockets only come on when the car
is started.

You might want to put a voltmeter across the power connector going to
your radio and across the battery, and compare voltages in transmit.
Methinks you'll find a rather substantial voltage drop through the
cigarette igniter jack. Also, that connector was never designed to
handle a plug and jack connector arrangement. It's the only connector
that I know of that has a spring which pushed the plug OUT of the jack
and lacks a retention system.

Jeff Liebermann
150 Felker St #D
Santa Cruz CA 95060
Skype: JeffLiebermann AE6KS 831-336-2558