>was pulling it out of its socket when the old Andrew dehydrator >about 2 feet behind the transmitter decided to kick on.
I've got a dehydrator on a dish antenna's waveguide and feedhorn at one of my transmitter sites that pulls that one on me every so often. There's something about being in the transmitter room by myself, getting immersed in the work, and then when the pressure has finally dropped enough to make the compressor kick on it startles me into orbit! Steve WD8DAS [email protected] http://www.wd8das.net/ ----------------------------------------------------- Radio is your best entertainment value. ----------------------------------------------------- -----Original Message----- From: Michael D. Harmon <[email protected]> To: [email protected] Sent: Mon, 12 Jan 2009 7:12 pm Subject: [AMRadio] "Hot" Broadcast Towers As a former broadcast engineer (MANY years ago), the discussions of hot towers, lighting transformers and base insulators caught my attention. One issue some of you may not have thought of is tower/antenna maintenance. Many AM stations never go off the air. Some of them run directional at night to avoid interference with other stations, and a lot more simply have a "night power" restriction, but the tower is fed with RF 24/7. You might ask how a worker can climb a tower while it's hot. Well, think about the birds perching on the 12,000 volt lines which run overhead through the community. If they are on the wire, they're at 12 kV potential, and don't even know it. On the other hand, I've seen entire sections of town blacked out because a hapless squirrel or raccoon tried to climb a pole with a "pole pig" (distribution transformer) mounted on it, and managed to get between the hot wire and ground. The answer is - they jump. They stand on the ground next to the tower base, give a giant leap and grab hold of the tower. Same way with getting off. Climb to the bottom, make sure all your belts, etc are completely loose, and give a giant spring backwards. I spent my time back in the early Seventies signing logs, trying to de-ice the elements after a winter storm, and getting late-night calls from a so called "audiophile" board operator who swore that the equalization had magically gotten out of whack (since he had come on duty) on the old Ampex AG-350 tape decks in the control room. Yes, I was one of those First Phone holders who were downgraded to the so-called "General Radiotelephone" license a few years later. I remember one cold blustery winter night when I got a call from the board man that the transmitter wasn't making power. I went in, and found a 4CX250B driver tube in our RCA BTF-10E FM transmitter that was getting VERY soft. After signoff (1:00 AM), I shut down the transmitter and went to work. The transmitter room was as quiet as a tomb after the blowers all shut off, and it was eerie having the station to myself. The plate supply in the transmitter was around 6,500 volts at about 2.5 amps, and I was painfully aware that I was the only guy there, so the need for caution was at the forefront of my mind. The driver tube was all the way in the back, under a shelf beneath the 4CX10,000D PA, and required an offset screwdriver to get the anode clamp loose. I opened the doors, hit everything with the grounding stick, and reached in and started loosening the plate clamp on the driver. I grabbed the tube, and was pulling it out of its socket when the old Andrew dehydrator about 2 feet behind the transmitter decided to kick on. "Karoom, CHUG, CHUG, CHUG ..." I swear it couldn't have scared me more if it had been a quarter stick of dynamite. I peeled the skin from my wrist all the way to my shoulder getting my arm out of that transmitter! I don't know how, but I never dropped the tube! After recovering from my shock (and changing my underwear), I put the new tube in, checked the driver and PA tuning and went home. It's been 35 years since that incident, but I still remember it like it was yesterday. I don't know if the technique for mounting and dismounting hot towers is still the same or not. With all the OSHA rules and concern over workplace safety, I'd be very surprised if there weren't some politically correct way to do it nowadays, but that's the way we did it in the Sixties and Seventies. Hope I didn't bore you with my story! 73, Mike Harmon, WB0LDJ mharmon at att dot net ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body.
