[Milsurplus] Base Carrier Current ( Milsurplus Vol 132 issue 4 )

[Ben Dover]

-----Original Message-----
>From: Bob Camp <kb8tq at n1k.org>
>Sent: Apr 10, 2015 6:12 PM
>To: milsurplus <milsurplus at mailman.qth.net>
>Subject: Re: [Milsurplus] Base Carrier Current ( Milsurplus Vol 132 issue 4 )
>
>Hi
>
>The main problem with most carrier current installations is that in building power feeds 
>are not designed as RF transmission lines. Toss in the stuff attached to them and the 
>impedance drops even further. Net result is a transmitter load that is < 1 ohm for a run in a large building. 
>
>If you start digging into these transmitters, the “interesting” part of them is the output matching
>setup. it’s also the part most likely to get nuked by spikes and lightning. It’s the first
>thing I’d check if I was buying one. 
>
>Bob
>


Actually, in my experience with a carrier current system the BIGGEST problem
was rotten audio, caused by 60 Hertz setting up a current loop thru the PA stage
and modulating EVERYTHING!!!

Multiple "antenna" tuner / matching network designs failed to alleviate the
problem.

I cheated; I cut loose from the power line, and ran a wire across the roof of each
building, and loaded the little 5 watt LPB transmitters into that.

Shady, but effective...


Incidentally, the low impedance wasn't all that much of a hassle, at least not to me;
by the time I wound up in college as the engineer for the carrier current station, I
was a veteran of running 160 meters MOBILE! Try running an 8 or 10 foot whip at 1810
KHz and you'll find exactly the same problem.



Mr. T., W9LBB