Trade ya War Stories, Fossil

A case of PEBKAC (Problem Exists Between Keyboard and Chair)? Tell us about your war stories!
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NECRAT
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Re: Re:"light flickering from a recliner"

Post by NECRAT » Thu Mar 01, 2012 8:08 pm

RGORJANCE wrote:This is a real SWAG! As I have heard, the VSWR triggering on the BTF-20 used a light and photo cell to turn the rig off when it sensed high VSWR, Could you have been "flashing" the xmttr with a light that might have been seen by the photocell???

Fossil
The Comark S series transmitters functioned similar to that. The beam current and VSWR meters , the actual meters had photo cells and a light. If the lamp burned out, the meter would "trip". My old transmitter had 4 beam current and 1 master VSWR meter with this technology and was in a "well lit" room , where the lights normally sat "off" (The only always on light on in the room was a single fixture near the door).. One night, got the page, system forward at 33%. Go to the TX room, notice V3 & V4 were off. (The configuration shared a common beam supply transformer). I walk over, turn the master lights in the room on.
"KER-CHUNK", the "off" side starts to recycle. Goes through the cycle, and powers itself on. Not seeing anything obvious, (I didn't think about the meter...), I shut the lights back off "KER-CHUNK". It drops. Thats when it occured to me, and sure enough, checking with the lights off, the V3 beam current meter lamp as out. I tapped it, the bulb came back on. I turned the main lights on in the room, and left. We replaced the lamp in the meter about two days later. (It was still working mind you, just to not have that happen again.)
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boiseengineer(old)

Re: Trade ya War Stories, Fossil

Post by boiseengineer(old) » Thu Mar 01, 2012 8:49 pm

Now my turn. Huh?

Re-word this. Every time the lights flickered the transmitter would go BANG.
The recliner was sitting in front of the transmitter.
Tower guy asleep in recliner.
Power up there was real bouncy back then. Many miles of 4400 volt line. Now ugraded to 34.5 kv.

Back when there were transmitter engineers up there the recliner was a handy place to sit durring lightning and watch the 8 foot arcs between the GE transmitter and the racks. You could then use the broom end to hit the overload resets and plate on.
Yes there was a 4" strap between them.

KE0MI
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Re: Trade ya War Stories, Fossil

Post by KE0MI » Fri Mar 02, 2012 9:17 am

My favorite is when we had a guy named Howard Small came in to turn two channel 2 TT25-FL RCA's into a 50 kW on channel 3. We had meticulously cleaned the step start relays for the vis plate supply with foamy windex (preferred at the time) to get rid of the dirt and grime. Time came to fire the rig up, and it sounded like a 12 gauge shotgun went off in the cabinet with a subsequent shower of black dielectric material in the room. After a "what the ???" moment to compose my thoughts, we found the windex had created a conductive path along the edges of the relay. We changed it with a new one and went on.

The Thales IOT setup I ran also crowbarred across the 35 kV and I never got used to it going off even when I knew it was going to trip. When a 1/2" piece of fiberglass six inches long can develop a carbon trace internally from exposure to the voltage across it, it gave me the respect to always keep one hand in my rear belt loop when I was in the cabinet.

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Re: Trade ya War Stories, Fossil

Post by n9lhm » Fri Mar 02, 2012 3:07 pm

boiseengineer wrote:Now my turn. Huh?

Re-word this. Every time the lights flickered the transmitter would go BANG.
The recliner was sitting in front of the transmitter.
Tower guy asleep in recliner.
Power up there was real bouncy back then. Many miles of 4400 volt line. Now ugraded to 34.5 kv.

Back when there were transmitter engineers up there the recliner was a handy place to sit durring lightning and watch the 8 foot arcs between the GE transmitter and the racks. You could then use the broom end to hit the overload resets and plate on.
Yes there was a 4" strap between them.
Okay, now I get it. I thought you meant every time the guy rocked in the recliner it made something arc over in the transmitter!

Never saw ambient light cause an issue with the API meters. The lamp and photocell were really buried in the back of the meter. IIRC there was a vane attached to the back of the meter movement that tripped the photocell. The system was fail safe in case the light bulb burned out and what generally happened was the light got blackened and dim with age and the meter thought there was a VSWR, body currrent, or whatever else the meter was metering, event and tripped the transmitter, usually in the middle of the 6P local news segment. :( The E-line FMs would let you defeat the VSWR protection and get back on the air right away and put off the repair till sign-off. The TV xmtrs. required you to change the lamp to clear the overload, which involved opening the back of the metering panel and removing two small 4-40 screws (and not dropping and losing them) so you could withdraw and replace the lamp, all the time while the transmitter phone is ringing off the hook and they're calling you on the two-way wondering when it was going to be back on.

The Harris UX series UHFs used external cavity klystrons and there were a lot of small holes in the cavities. If you tried to take pictures with a camera equipped with a strobe flash around the back of the transmitter, enough light would get inside the cavities to trip the arc detectors.

No wonder what little hair I have left is grey :P

Brian

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Shane
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Re: Trade ya War Stories, Fossil

Post by Shane » Sun Mar 04, 2012 4:10 pm

Never saw ambient light cause an issue with the API meters.
The BTFs were the other way around - light would trip it. They didn't require the lamp to be operative to operate.

The same site where I was cleaning up mouse guts out of the BTF in that earlier story had a south-facing door, which in hot weather we would sometimes leave open while working in the building. One time we had the transmitter on the air (remember this was the aux so this rig wasn't normally used much) and had been working in the building during the day for some time. All of a sudden - KER-CHUNK!

Attempts to revive the transmitter failed until one of us noticed the sun shining on the VSWR meter. Well, as they say, Shut the front door! Transmitter came right back up.
Mike Shane, CBRE
---Omaha---

boiseengineer(old)

Re: Trade ya War Stories, Fossil

Post by boiseengineer(old) » Sun Mar 04, 2012 11:27 pm

You forget the BTFs forward power meter with its minimum power setpoint. Factory setting was 60%. SOL if you have to reduce power due to icing. Unlike the VSWR meter, if the lightbulb burned out you were off the air.

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Re: Trade ya War Stories, Fossil

Post by Kent T » Wed Dec 19, 2012 6:30 pm

And tuning a BTF 20 itself requires mucho patience. Tune for minimum smoke. Especially as they are well known for combustible status. aka "things which go flash, bang, and poof"

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Re: Trade ya War Stories, Fossil

Post by Dale H. Cook » Wed Dec 19, 2012 11:08 pm

Kent T wrote:And tuning a BTF 20 itself requires mucho patience.
Having worked on a combined pair of 20Es and, earlier, on a 10E, I can testify that the BTF-20E used a damn good 10 kw cavity. I never lost finger stock or anything else in the 10, but needed to stock plenty of spare parts for the 20s.
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Re: Trade ya War Stories, Fossil

Post by RGORJANCE » Thu Dec 20, 2012 7:51 am

Just when I thought it was safe to go back in the water, this headline pops up again!!!

I recall a time, and another (non-bcst) story, when I was a "draft dodger", (having enlisted in the USAF), working in a major crypto shop in Germany back in '62.

We were in the final completion stages of finishing up a new comm center with over 100 circuits (two pieces of crypto gear per circuit) and were ready to apply power and start setting up the links. We didn't have the AC power capacity in our power shack so the USAF brought in a portable generator the size of a semi trailer. They get it installed and call down to the crypto shop for us to " provide a load to test the gen". As I hang up the phone, I holler to the crew that the power guys want us to turn on the equip. So 6 guys run over and turn everything on (that's over 200 pieces of gear). After about 10 seconds of load, all the lights go out, and I mean ALL the lights go out! This starts a chorus of belly laughs, guffaws, etc. The phone rings, I answer it and the screaming power shack guy says "I asked for a load, not a dead short"!!! :lol: :lol: :lol:

I think that we either caused the generator to come to a screeching halt, or we took out all the circuit breakers on the gen. That was fun.

Fossil

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Re: Trade ya War Stories, Fossil

Post by Kent T » Thu Dec 20, 2012 7:52 am

Dale,

The BTF 10 was a better transmitter in those areas than the BTF 20. Now running combined BTF 20 transmitters, that was a real beastie to tame. Tune for minimum smoke. We called our BTF 20 Dolly Parton. 10 KW of Cavity in a 20 KW Sack. And you needed to keep a full stock of parts for that cavity, especially in the tube socket department.

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Re: Trade ya War Stories, Fossil

Post by n9lhm » Wed Jan 02, 2013 2:09 pm

I had a lot better luck with the 20's then you did. Took care of a 5E and two 20Es at different stations. Never had a cavity problem with them. They were great units. What was so difficult about tuning them? You could do a tube change in five minutes, carrier off to carrier back on, and tune them up on the fly. Peak the grid and peak the plate and you were set. What required so much patience?

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Re: Trade ya War Stories, Fossil

Post by Dale H. Cook » Wed Jan 02, 2013 3:28 pm

n9lhm wrote:What required so much patience?
What required patience from Kent might have been running a BTF-40, to which he refers - a combined pair of 20s. I was the backup CE for some years for a station that ran a 40, and after a major repair it could be a real PITA to get those 20s to play nicely together.

How much grief a 20 gave you depended upon a number of factors. One of the foremost was TPO - the higher the TPO the more likely the grief. Another factor was the condition of the line and antenna, as any significant SWR could compound problems. Yet another factor was how well the transmitter had been maintained, as finger stock and cavity walls that had not been kept clean could lead to failure. As Kent and I have noted the same cavity in a 10 had plenty of headroom and was much less prone to failure.
Dale H. Cook, Contract Engineer, Roanoke/Lynchburg, VA
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Kent T
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Re: Trade ya War Stories, Fossil

Post by Kent T » Fri Jan 04, 2013 7:59 pm

Remember too, my combined pair of BTF 20 transmitters were third hand, less than ideally maintained, and also had to meet 34 KW TPO. Not conditions which made life with them easy. I did the best I could to clean them up, maintain them better, and keep them cool and happy with the antenna they worked into. 2 years after they were installed, a new pair of 20 KW Continentals were purchased and installed, much more reliable every day, and that pair is still mains.

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Re: Trade ya War Stories, Fossil

Post by Baylink » Tue Feb 26, 2013 10:57 am

*Wow*, did this thread need the comment "Hey, Eddie; a little bullshitting music, please..." :-)

Fun stories, guys.

I have two of my own, one much teenier, and one much larger, though I wasn't involved in the latter.

When I was in my 20s, MUMBLE years ago, I was a bit of a photography nut -- which was much cheaper, cause I was driving delivery for a lab, and got my film processing free and my prints at cost.

Somewhere along the way, I acquired a shoulder-bag flash; one with a 5-turn flash tube in a 6 inch reflector on a bracket, and 2 225V batteries in it. (Try to find those nowadays, I dare you. :-)

At one point, I decided, hey! wouldn't it be cool to have a "Charged" light on the thing? So I got an NE-2 with leads, and whipped out my voltmeter to find out what full charge voltage was, and dutifully calculated the required size of series resistor, and set about modifying the puppy.

About halfway through, I somehow managed to get the leads of the neon bulb directly across the output buss of the capacitor pack, without the resistor.

8 of them.

About 250uF apiece at 500VDC, IIRC.

You know how load a bang an NE-2 makes when you dump that many joules into it?

My roommates all came running; I couldn't hear anything at all for at least 2 hours; not even ringing, initially; it was about a foot from my face. Luckily, all the glass went different directions; we pried one rather large chunk out of the drywall.

Pretty sure I abandoned the project that point; yes, I'm a wimp.

The other one I got second hand. In the early 90s sometime, St Petersburg FL spent about 12 hours one day with all it's police cruisers fanned out across the city. So people would have a place to go to report fires.

Cause the main CO wasn't even giving out *battery* for that long, much less dialtone.

You see; how it happened was this way:

Apparently, as I got the story, some newbie who was working at the SPBGFLXA89H CO -- that's a GTD5EAX and a pair of 5ESS remotes, which take up 2/3 of a floor; most of the rest of the 7 story building is empty now, or CLEC colo space -- went into the battery room. And didn't know that there's a *reason* you only use vinyl dipped tools in the battery room.

I've personally seen that battery room on a tour, it's rated for, I think they told me, -52VDC nominal at about 8000A *continuous*.

He managed to get a heavy-duty 12" long wrench, a crescent, I think, *across the main bussbars*. You thought *my* pop was loud? He couldn't hear for *days*. Seems the wrench continued to exist *just* long enough before flashing into plasma to open some Really Large Fuse for which they did not have a local replacement, figuring that their Defense was in sufficient Depth, and it took them that long to clear it up. I'll assume he got fired for it, once he could hear them again. I was told they never found *any* of the wrench; just the dents on the busses.

I may have a few of the details wrong (and would adore corrections), but that was how I got it from the guy who gave me the tour...

GigaHurts NoPain
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Re: Trade ya War Stories, Fossil

Post by GigaHurts NoPain » Fri Feb 28, 2014 8:56 pm

Not transmitter related, but related to high voltages and over helpful assistants.

A road weary electrician was traveling with a rock band on tour. He had a young kid just out of school with him, book smart, but real world innocent. At one venue another power feed was needed and the rest of the show couldn't be powered down. Seeing a learning opportunity for the young lad he thought he'd demonstrate how to tap a hot circuit. He got his insulated gloves and tools and handed a 2x4 to the kid. "If I screw up, use this to break me off the panel". The kid was a bit alarmed at an obviously unsafe practice, but since he was there to learn dutifully watched with 2x4 in hand. As the, the old electrician reached in to make the first connection, he realized he had the wrong size allen wrench in his hand. He mumbled "Sh!t". At which point, the kid already uncomfortable with the process, thinks the worst has happened and knocks the electrician into the wall breaking three of his ribs. It was shortly after that they decided their styles didn't mesh.

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