A Day in the life of an AM Broadcast Transmitter
|Nobody loves me. |
Nobody pays any attention to me. It gets lonely out here in this isolated field - save for the occasional kids parking - or hunters chasing a deer through here -- NOBODY comes to visit.
|No-one - that is - unless I throw a fit. |
And boy - did I throw a dandy this past Friday afternoon. I planned it pretty well - I waited until after 4PM - then started throwing flames.
(L3 70Khz PDM filter coil. This has (depending on modulation level) between 10KV and 15KV at 70Khz on it - up to an amp (audio) through it - this is in the "modulation chain" - in the cathode circuit of the PA (power amplifier)).
|At first - no one noticed - but after some parts starting melting; wires exploding - my signal - carrier and all -- would just drop to nothing for a second - then back to full power for 5 - 10 seconds --- then those blasted safety circuits would detect the arcs - shut down long enough to extingusih them - but then let me have some power back for 5 - 10 seconds. While I could - I flamed away! boy did I flame away!!! Made a real mess!!!! |
(Debris scattered over the lower modulator deck. Notice the shorting stick - this is one of two permanently mounted / wired shorting sticks -- often called "Jesus sticks" -- 'cause forgetting to use them can get you to meet Jesus real quick in one of these.)
(Debris even all the way over into the PA side of the chest.)
(Crud even down into the high voltage supply - those green (and one black) things are the 12 phase 15KV 1.1Amp high voltage supply - the huge (1000 pounds) main transformer is behind them. The solenoid above left is one of two safety shorting "relays" to protect people working on the transmitter.)
|Sure enough - with in a few minutes - the owner and the engineer showed up - checked some stuff - and shut off the power. Not what I had in mind. I wanted to visit - and they turned me off completely. NOT FAIR!!!! |
I thought by waiting so late on Friday - they'd fuss with me over the weekend...
|I slept until around 2:30PM the next day (Saturday, June 19) when suddenly I woke up. All the nasty dirt, crud and muck had been cleaned out of me - the debris from my flame-fest was all gone - the part I'd taken my ire out on had been replaced with a brand-new one. How on earth did they get that part so fast? (Thanks to Harris Broadcasting -- including Jim Swift, Vicky and all those nice people - and of course FedEx - when it absolutely positively had to be here - it was!!!!!!)|
At least the engineer was fusing over me - checking readings - and FINALLY - POWER - throttled back for sure - but back on the air. For the next hour - the engineer fussed over me - peaked grid drive - dipped my plate - set the HV to 5000V - then loading to 5000W - finally - full power!
He stayed a while then went away. But then about 4PM he came again - checked and fussed. Tweaked some more. Gee - it was so great to have some one care. I guess I'll settle in for a few weeks - I heard the engineer comment my PA was getting long in the tooth - drive was falling off a bit- so he'll be back in not too long to take care of that. He better be - or I'll find something else to throw a flame fest at...
Yeah - I got their attention - they're not going to ignore me - at least for a while - I've got 'em worried good!!!!!!