[AMRadio] Today's AC Mains voltage too high for many BA Rigs

[AA8TV at aol.com]

Hi John,

I don't have a digital camera of my own, but can easily borrow one and send 
you a picture. They are heavy. About 70lbs. They use no filtering. They are 
high quality, audio power amplifiers, in series with the secondary of a split 
bobbin, shielded power transformer. The transformer is responsible for most 
of the weight. The amplifier can make about 70 volt ac, and is connected in 
series with about an 80 volt winding of the transformer. They use an 
oscillator, that is PLL locked to the line, and the output of this oscillator 
is the reference to the amplifier. The amplifier will buck or boost, real 
time, to make the output look just like the input. (the sine wave oscillator) 
The transformer in these units are beautiful. They have full faraday 
shielding between primary and secondary, including shielded coax type leads 
in and out. The line is completely isolated from the load. The unit is 
configurable to allow full isolation including it's own floating neutral. 
These units are beautifully built, and were well over $1000 when they were 
new 25yrs ago, but they can be found today for about $35 on the used market.

The only thing I did before using them in the shack, was to install 20amp EMI 
filters on the input and output. This is to keep rf out of the unit. I run 
legal limit from time to time and didn't want rf getting in and causing it to 
misbehave. Although I have not tried running them without the filters. The 
units may work just fine without them. I mounted the input filter directly on 
the rear apron. I cut the power cord and ran it through the filter first. The 
output filter is identical to the input filter. I have a short power cord 
(about 8") plugged into the back of the line conditioner, and the filters 
output is connected to a power strip where I have all my radio gear plugged 
in.

I'll send you a picture as soon as I can John. They are distinctive looking 
enough to spot them from a distance at a flea market. They are a great asset 
to any shack.

73, Ed
AA8TV