Tuesday, February 19, 2002 4:33 PM
I enjoyed your piece on the beast. One other fact I would note is that they were capable of very high S/N. In a world where 62 dB was the state of the art, the phasitron could approach 90 dB.
In so far as the serrasoid exciter is concerned, the first one I worked with in 1961 was made by Dwight Red Harkins. He was the one who wrote the "Scratchy" column in CQ magazine back in the 50s.
The serrasoid's inherent problem was that the crystal frequency (around 100 khZ) had to be tuned out in the plate circuit of the first tripler or it would show up as an unwanted 1% subcarrier in the output. Adding a subcarrier had to be accomplished with a second phase modulator someplace in the multiplier chain. The overall multiplier was about 1000. An improved exciter was made by Standard Electronics around that time. They were a spinoff from Western Electric.
I worked on a Western Electric transmitter that had the motor driven butterfly capacitor for carrier correction. The motor circuit was driven by Western Electric 350B tubes which were essentially a very rugged 807 without the plate cap. When you turned the transmitter off the tubes took 2 minutes to lose filament glow. There was no record that one had ever been replaced.
All of the WE xmitter cabinets had a big front interlocked glass door that made it look like a deli case. Story goes some wag hung a salami inside one and the station got inspected that day.
Roy Trumbull
Another e-mail from Roy Trumbull:
Wednesday, February 20, 2002 10:14 AM
Two other stories I remembered from the early 60s happened at a mountain top antenna farm. There was one joker in the pack who made it hot for the rest of us.
In those days there were a lot of tar filled xformer and inductor cans sticking out the front of xmitters. This guy had a shorted winding in one such xformer which resulted in a puddle of tar on the cabinet lip below. He carefully scraped it up and, over time, placed it in all the other transmitters to get a rise out of us.
One of the CEs was a tall southernor who had recently nursed a composite remote control back to life by taking apart the stepping switch and cleaning it. One night the joker wired a sparkler under the chassis and called the CE into the room. He was smoking at the time and his jaw dropped leaving the cigarette dangling from his lower lip.
Months later the joker asked me if I'd seen the victim CE that night as he'd gone to get something out of his car and the car was gone. The joker figured it might be payback time. The site was on a sugarloaf kind of hill. The joker had forgotten to set his own hand break and at dawn, we found his car halfway down the hill. It hadn't picked up too much speed before it was stopped by a boulder with only minor damage to the vehicle.
Roy
Another e-mail from Roy Trumbull:
Tuesday, April 30, 2002 1:59 PM
David,
That exciter looks great.
There's a couple of guys in the Bay Area that restore old broadcast transmitters. I don't know if they've done a GE.
The GE FM was 250w to 3kW to 10 kW. The 10 kW cabinet used some very expensive tubes that didn't last all that long. A PE named Al Isberg designed a kit that converted the amp to grounded grid using a much more economical tube. Many of those amps were converted to that configuration in the 1960s.
One further story on my friend the joker. He decided to update a spare exciter by replacing all the old capacitors with mylar caps, which had just recently come on the market (@ 1961). That was fine as far as replacing the old paper caps was concerned but he also replaced the mica caps and after that the exciter wouldn't work. He had to retrace his steps and put the micas back in.
Roy