This here is a Little Blue Arc.

It may be familiar to those of us who have worked on R.C.A. transmitters in the past.

Why ? Because the way RCA made their plate voltmeter multipilers was to take a large number of little resistors, all merrily daisy-chained along on a single PC Card. That way the stress on a single resistor won't be too much.

The case in point ? A venerable R.C.A. BTF-1B transmitter that powered a station Mike put on the air in Camarillo.

And the transmitter ran, fine, thank you.
I bought it from Milan Leggett at KWST for $ 1 a watt. $ 1,000 worth.

But, shortly after going on the air, I noticed that even though the Power Out and the Plate Amps read just fine on the meters, the plate volts read '0'...

Sort of like screaming down the freeway with your speedometer reading '0'. You just sorta know something's not right.

But I knew how to fix it. The problem is simple, one of the solder connections in the mulitplier resistors is bad.

And you find it by running the transmitter in the dark, propping the door open, and then you look for a 'little blue arc'

And then you solder the bad connection...

So, that's what I decided to do. I enlisted the help of an old-time friend of mine, Dennis Dreier, and we laughingly sallied forth to the transmitter. We were in good spirits; this was going to be a fast repair, and we should be finished and back on the road in an hour.

But, first, we had to get the transmitter to run with the back door open. There are two safety thingies back there. One of them keeps the power off unless the doors closed. Kind of like the opposite of a refrigerator light. This one goes OFF when the door's open.

And it was easy to fix. I just wrapped tape around the switch until it thought the door was closed all the time.

The other safety feature is a 'High Voltage Interlock'. This one is really simple, it just shorts out the High Voltage when the door's open. So, I decided to just stick something in there to keep the pluses and minuses separate from each other.

I smoked like a chimney in those days, so I took my cigarettes and stuck them into the gap.

We were ready. So I asked Dennis to stand behind the transmitter, and to wait with me until his eyes got used to the dark.

So there we were - lights off - shooting the breeze, until I asked him if his eyes were used to the dark.

'Yep'

'O.K.' now remember, you're looking for a tiny little blue arc.'

"Little Tiny Blue Arc, Got It'

'Are you sure you're ready ?'

'Look - Will you turn the darned thing on ?'

So, I turned the Transmitter on.

And this is what Dennis saw :


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