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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Trade ya War Stories, Fossil

Post by RFWarrior » Mon Jan 12, 2009 5:24 pm

Hey Old Timer...

A certain gentleman from the Windy City was here today for some snow (don't know why he came here, seems like Chi has enough of its own, but hey, maybe it was our sunny Maritime dispositions he wanted to witness :D)

Anyway...

I'll tell you how I learned that crystals don't come up on the right frequency if you could elucidate on how a certain salesman discovered that navy blue suits with brass buttons might not be the best uniform for a Sales Engineer... and please be your usual descriptive self, I need to see if you can tell the story with as much enthusiasm as Gord...erm..... our visitor did :D Of course, if you tell him I told you he told me, I'll pretend I don't know what you are talking about :P

Best,

Jeff

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Re: Trade ya War Stories, Fossil

Post by BroadcastDoc » Mon Jan 12, 2009 8:18 pm

Bob told me that one, it's a GREAT story! :D
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Re: Trade ya War Stories, Fossil

Post by Muadeeb » Mon Jan 12, 2009 10:10 pm

Pooh Bear story time?? Count me in!!! :P :P :P
Procrastination I can totally do. I'm good at it, I have a black belt in procrastination, it's an art form for me, I'm the absolute King of, well, I'll finish this thought la

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Re: Trade ya War Stories, Fossil

Post by RGORJANCE » Tue Jan 13, 2009 6:39 am

So that's how it is! And I thought that all these folks were my friends. Well, I guess when you've been around as long as I have you can say "with friends like these, who needs enemies"?

I will relate the story, but since I am without caffein, and undergoing severe withdrawal symptoms, I will be back shortly. You want it, you got it. Toyota!

Gordy, I'll deal with you later.

Da Fossil

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Re: Trade ya War Stories, Fossil

Post by RGORJANCE » Tue Jan 13, 2009 7:38 am

I got the coffee.

I was making a sales call to an un-named radio station in the un-named city of Crystal Lake, IL. and the chief engineer and I got to talking about his Go-Carts in the Harris automation. As the fuzzy brain recalls, the subject matter was the photocell that was part of the tray counting/positioning system. The subject matter dealt with a high ambient light wash-out of the cell, and how dust could effect the operation.

These were the 78 tray machines-customer had two. And to insert an important correction to the story, the suit did not have the brass buttons, they were on the vest!. (yes, young people, vests were popular back then)

We opened the rear rack door and I leaned forward to point out the position of the photo cell, when we both heard a subtle little POP! The Go Cart had met Bob's brass buttons and a chip in the electronics got zapped. A call to Quinky revealed that the device determined how many trays the machine had. (remember this) A new set of devices was promptly dispatched to the airport. This I must point out was before FEDEX. As luck would have it, Quinky was fogged in and even the geese were walking. So there were some delays in getting the parts headed North. Finally the parts arrived and were installed. Unit started working immediately, but it was soon discovered that some spots wouldn't play. Yup, Quinky sent the parts for the 48 tray Go Cart, not the 78.

The next thing we learned was that a plastic shield was being factory installed on all Go Carts as it was determined that lethal voltages were present on this board. So, after all, the call I made at this station, the subsequent discovery of "A DANGEROUS CONDITION", was truly a humanitarian service in the finest traditions of field sales. Better stated-how to be a bum and hero at the same time.

And so ends the story of how I obtained the Chicago area knickname of "Buttons".

Fossil :roll: :oops:

Jeff, your turn.

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Re: Trade ya War Stories, Fossil

Post by RFWarrior » Tue Jan 13, 2009 8:40 am

Just the image of Bob in a suit and vest made that all worthwhile :)

Since turnabout is fair play, and since I did start it, here goes....

I was doing a transmitter install back in the field service days - about 10 years ago I'd guess, based on the transmitter model. This was out in Western Canada. Typically, what happens for the lonely field service tech is that he flies 8-10 hours to the west, to get to some place where it's just past noon, even though he's been traveling for pretty much a full day (i.e., leave home at 4:00 AM Atlantic, travel through four time zones to get to destination at noon Pacific, or 4 PM Atlantic). Since it's only noon, of course the customer figures we might as well go to the site right now. I was still young at the time enough to believe I can do anything, standing on my head while drinking a glass of water and whistling the Ave Maria (that's changed since then). So I say sure and we grab a bite at some fast food place and head to the site. I walk in to see a shiny new 50kW AM transmitter just waiting for the tender touch of the factory guy to bless it and bring it to life. So, that's what we start to do... It's about 2:00 pm local, I've been going for 14 hrs so far, no problem.

Twelve hours later, the last switch has been thrown, the last voltage measured, the last reading taken and the transmitter is fully functional and ready to go on air. At this point, I've got enough caffeine in me to believe I'm still wide awake (doesn't everybody vibrate as part of the normal course of being awake?) and the customer asks about automatic exciter transfer. Transmitter is sitting there, pumping out 50kW and yours truly reaches up and pulls the crystal out of the oscillator in exciter A. "Sure", I say, "it will transfer automatically". Sure enough, it goes down when I pull the crystal, and three seconds later, pops right back up on exciter B. No problem so far.

Now, we get to the tricky part. Exciter transfer is a 'one-way, one-time' thing. Working on the theory that you will reset the transfer function when you fix the defective exciter, there is no point in switching back to a failed unit if the other goes down. So, I show the guy how to reset the exciter transfer function by selecting the now operating standby exciter as the main. Now the exciter transfer function is fully functional again - and I demonstrate by pulling the crystal out of exciter B. Transmitter dutifully goes down. At this point, I realize that I have not reconnected the crystal in exciter A, so I reach up and plug it in - about half a second after the transmitter attempts to come up on that exciter.

The transmitter made a sound sort of like I had dropped a kitten into a blender, and then there were a series of popping sounds - and several red lights came on. Apparently, crystals do not immediately oscillate at the desired frequency when first biased - in fact, it appears that they are not even close. Moreover, semiconductors with a 2MHz top end spec for switching tend to be significantly unhappy when asked to oscillate at much higher frequencies. I don't know exactly how high, but in this particular transmitter there were ten power modules, each containing 8 power amplifiers. If you are counting, that's a total of 80 power amps, with 8 MOSFETs in each (640 MOSFETs). I managed to blow 20 PA's.

Never one to miss a beat, I looked at the customer and said, "and this is where you get to learn and practice module repair"... we ran out of parts and spare modules about six hours later and he was highly proficient at the skill. Got exchanges for the remaining 12 or so power amps sent out from the factory and put the system on air - rigorously tested. As a matter of fact, I just checked and there has not been a reported failure since installation - guess I took care of the whole lifespan of failures for that system!

Fortunately, except for the one customer, there were no witnesses, and he was quite a ways out of the loop, so the story didn't get around. So I can't boast any fancy nicknames - but give me time, I'm sure they're coming!

Next?

Best,

Jeff

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Re: Trade ya War Stories, Fossil

Post by RGORJANCE » Tue Jan 13, 2009 1:50 pm

Jeff, now you've done it! You have thrown down the gauntlet.

Here is another good one.

"Back in the day" when I was wearing "the suit", I had a customer from the Quad Cities in to look over some automation equipment at the factory in Quinky. I won't reveal, the name of the customer , but he became a famous remote control equipment manufacturer years later.

Anyway, we were touring the factory, and were nearly done with the tour when the 3pm coffee break alarm went off. We stopped at the near North end of the building near the xmttr test lab to get some brake fluid (coffee) out of the machine. The noise coming out of the test lab, just on the other side of the vending machines was really loud. I commented that it was a 20kw FM xmttr on test. This was prior to a redesign on the blower motor and cooling path for that box that really helped reduce the blower noise. We were talking fairly loud to be heard over the fan noise, when there was a GIGANTIC FLASH OF LIGHT, AND A HORRENDOUSLY LOUD EXPLOSION. (especially loud due to the concrete floor and a very acoustically hard structure) Since we were both facing the lab, we observed this boiling big mushroom shaped cloud rapidly rising into the gridwork steel of the roof. As the loud fan noise gradually dropped off, we heard some of the biggest belly laughs ever. I suspect there might have been a "minor malfunction" in the 9500 volt power cubicle. We finished the coffee and left the building.

About a week later I was talking to another salesman relating the experience. As luck would have it, he and his customer were witnessing the test of the rig prior to shipment. As the noise, smoke and the particulate matter stopped falling, the customer calmly turned to the salesman and said, "IT'S STILL YOUR TRANSMITTER".>

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Re: Trade ya War Stories, Fossil

Post by RFWarrior » Tue Jan 13, 2009 2:40 pm

RGORJANCE wrote:As the noise, smoke and the particulate matter stopped falling, the customer calmly turned to the salesman and said, "IT'S STILL YOUR TRANSMITTER".>
Hah, that's perfect :lol:

Now that you've dragged factory BOOM stories out, assuming everybody else hasn't either fled the forum or just deleted us, I'll take my turn - I've got a few, so I'll make this interactive - everybody can vote on which they want to read next :D Then it will be Pooh Bear's turn - or anybody else can feel free to chime in at any time, I'm sure there are lots of other times things have gone BOOM with a factory guy standing there! So, what would you like to hear about first...

a) How we shut down power to our entire community for a few minutes one day?
b) What happens when the Sales Manager tells the customer, "you can't blow this transmitter up"?
c) What happens when the test supervisor plays, "let me reset the breaker again, and we'll see if it trips" about 20 times?
d) Why you shouldn't modify test equipment?
e) How Michael Jackson can cause lightning?

Y'all pick one and I'll get going on it - let's see how many good ones we can get out there. Seems like there are lots of "stupid user stories", so let's share the mistakes we can make before you get your shiny new transmitter!

Best,

Jeff

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Re: Trade ya War Stories, Fossil

Post by BroadcastDoc » Tue Jan 13, 2009 7:52 pm

Oh boy, so many good ones!

I vote for "a" first.

Here's one, though not nearly as interesting...

I worked at an FM that was running an old Collins 831-D1. The transmitter was in an old building that used to house the studios and offices. One night, while getting ready to do some late night maintenance, I went to the bathroom to relieve myself. Just as I started to go, I hear a loud "BANG" followed by the sound of a blower spinning down.

So here I am trying to finish up, mind racing trying to figure out what happened. I get finished, walk into the transmitter room and find the transmitter dead. I hit the buttons, nothing happens. So, I open the front door, and immediately see a large open space. I then look down and find the culprit.

At some point many years ago, an Engineer removed the Z10 exciter from the 831-D1. Apparently, this guy didn't have any rack panels to use as filler, so he duct taped an aluminum panel to cover the hole. The tape had dried up, and at the very moment I was using the facilities, broke loose. The panel fell down, turning all the breakers off along the way!
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Re: Trade ya War Stories, Fossil

Post by W9PXZ » Tue Jan 13, 2009 8:20 pm

RFWarrior wrote: a) How we shut down power to our entire community for a few minutes one day?
b) What happens when the Sales Manager tells the customer, "you can't blow this transmitter up"?
c) What happens when the test supervisor plays, "let me reset the breaker again, and we'll see if it trips" about 20 times?
d) Why you shouldn't modify test equipment?
e) How Michael Jackson can cause lightning?

Y'all pick one and I'll get going on it - let's see how many good ones we can get out there. Seems like there are lots of "stupid user stories", so let's share the mistakes we can make before you get your shiny new transmitter!

Best,

Jeff
A, B, and D sound quite interesting to me. In the case of A, I have managed to cut power to the building one by popping the mains fuses, but never to an entire area.

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Re: Trade ya War Stories, Fossil

Post by eadler » Tue Jan 13, 2009 10:28 pm

W9PXZ wrote:A, B, and D sound quite interesting to me. In the case of A, I have managed to cut power to the building one by popping the mains fuses, but never to an entire area.
You used a transmitter for that? We somehow managed to do that with a desktop PC once.... :roll:
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Re: Trade ya War Stories, Fossil

Post by RFWarrior » Wed Jan 14, 2009 5:03 am

eadler wrote:You used a transmitter for that? We somehow managed to do that with a desktop PC once.... :roll:
Wow, best I've been able to do is to trip the circuit breaker feeding my office - and that ultimately turned out to be a bad breaker! I'd love to hear this one when you have a chance, Eric!

And Doc, having been close to that situation when a respectable BANG happened, I'm surprised you had to wait to finish - but be glad it wasn't a case of "first you say it, then you do it!" :D

Okay, it's early and I've got coffee, we'll start with A, since it's at the top of the list :P.

Not terribly many years ago, we took the plunge into higher power AM transmitters and we had 400kW for Trans World Radio in the test bay. This was 2 x 200kW combined, so the whole rig was over 40 feet, end to end - we had to build a special test area onto the plant to accommodate it before we could build the transmitter - it was built in its test bay (but I digress).

At that time, we had an 800kVA pad mount entrance transformer. The power company told us that it was very conservatively rated and that it "should" be able to handle 1.5MW for up to 30 minutes or so. We figured fine. To play it safe, Engineering scheduled test of the transmitter during our annual planned summer shutdown, so that normal operating power consumption would be at an absolute minimum. So far, so good.

As any of you AM folks know, power consumption of an AM transmitter increases with modulation. Further, a sine wave requires significantly more current to produce than program, due to the much higher average signal level. For example, a 400kW transmitter that is 85% overall efficient, will draw 470.59kVA of power with no modulation (I'm assuming unity power factor to make life easier). The same transmitter with 100% program audio will draw 583.53kVA, and with 100% sine wave audio applied, will draw 705.88kVA. Easy math so far. Now the catch....

The test protocol for this particular transmitter was provided by the customer - it was to be located in a fairly remote area of the world, in a region known for unrest, upheaval and strife, so the customer wanted to be certain it would be rugged and that it would survive unattended if the staff had to relocate to safer climes for any period of time. To do this, customers usually devise tests that would never be experienced in any aspect of normal operation, but that will tax the equipment to its fullest capability (we call this game, "let's see if THIS will make it blow up"). This particular customer was no exception - the test of interest was a pulsed 100Hz square wave, at 95% modulation. Effectively, 10 seconds on, 2 seconds off, for 30 minutes.

The thing to remember here is that, for square wave modulation, average power output is effectively peak power output for the duration of the signal. So, for 10 seconds, the power consumption of the transmitter was pushing 900kVA. Remember I said that the nameplate rating on the pad mounted AC entrance transformer was 800kVA, power company promises notwithstanding.

Apparently, when they started the test, every light in the building - and nearby parts of the community, dimmed for 10 seconds, then restored for two, then dimmed for ten and restored for two, and so on. This lasted for about 5 minutes.....

Around that point, one of our dedicated Fabrication Shop employees came in to get a jump on the workload. He programmed up a machine, loaded in a sheet of 4 x 8 foot aluminum and hit the go button. Did I mention that the machine in function was a CNC punch press that is about the size of a pair of Hummers and that it boasts a fairly respectable power consumption of its own? When the guy in the metal shop hit the go button, the entire facility shook, instead of just the one building that would normally be rocking and rolling when the punch is going. The shaking occured for about 30 seconds, then everything went dark... literally everything. About 30 seconds later, we smelled smoke - and looked outside to see that the pad mount transformer was cooking up like a Thanksgiving turkey in a deep fryer with a runaway thermostat.

Turned out that the transformer that was "conservatively rated and should handle 1.5MW for up to 30 minutes" was actually mislabeled and shouldn't have been providing 1MW, let alone the nearly 1.5MW that we were asking of it. When it cooked up, instead of tripping the fuses at the pole pigs, it apparently fired just about every protection circuit at our local substation and required manual intervention to reset - we took down everything on the circuit, so about 15 miles of houses on a fairly populous road were down. We were told that the brownout created before the protection circuits tripped created several trouble tickets and one report of alien invasion (don't ask, that's a totally non-transmitter related story). The transformer in question was replaced, the new one is nameplate rated for 2megawatts and "should handle up to 3 MW for up to 30 minutes..." 8) :wink:

And Fossil - I have my own "Bang/Flash" story, going back to the days when my office was right above the engineering test lab - I forgot to put that one on the list, maybe I'll get to it later if interest in the thread maintains :)

Best,

Jeff
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Re: Trade ya War Stories, Fossil

Post by RGORJANCE » Wed Jan 14, 2009 7:36 am

Jeff:

Since I was only in the office in Quinky for 2 1/2years, the stories I have are kinda limited. You will have many more than I have.

Here's one I remember hearing about. We had an outstanding AM xmttr project engineer who had a very low skin resistance. He would actually have a fairly large jerk reaction from a 67.5V battery. One day, he was doing a demo for customers on an MW-50. One test was to take a "chicken stick" and demonstrate a direct short on the output connector with the beast at full power to show how fast the xmttr shut off the RF.

What he didn't know was that the VSWR trigger was somehow disabled. Well, he hit the output and then there was this violent hissing arc that didn't go out. The report went on to say that he threw the stick away which hit the cabinet with lots of noise and then the overloads took over and shut things down. The last thing they saw was this fellow making tracks South for points unknown. I suspect he headed for the bathroom. Fortunately no one was injured.

Bob

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Re: Trade ya War Stories, Fossil

Post by RFWarrior » Thu Jan 15, 2009 6:16 pm

RGORJANCE wrote:Since I was only in the office in Quinky for 2 1/2years, the stories I have are kinda limited. You will have many more than I have.
Mebbe one or two more from the test room perspective, but you aren't any slouch in the story telling department yourself - I seem to recall propping up against a table in Madison or Milwaukee (can't remember exactly :() and learning a thing or two :)

I'm leaving the floor open for somebody else to share their "and then it went BOOM" story - Doc is probably the only one that will mix biology and transmitters (although usually you wet yourself AFTER the boom :D) - but I'm interested in any and all :) Let's have one or two others, then I'll get back to my list!

Best,

Jeff

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Re: Trade ya War Stories, Fossil

Post by NECRAT » Thu Jan 15, 2009 7:55 pm

Would a High School boom story suffice?

I was part of our high school's "technical and engineering" department. Which in our school meant everything from electrical (AC) work to equipment repair, to travelling to other schools to work on equipment, fire alarm, wiring, etc.

Got a report from the auto-shop in the school that the welder was dead. Get there, sure enough, welder outlet has no power. The auto shop had an electrical buss tray with tray-breakers hanging off the side, and these cords which hung down from the breakers. So instinctivley, i shut the power off to the buss (a 300 amp disconnect). Got to the tray breaker, found it in the tripped position. So I reset it, went over, reset the buss breaker... BOOM! the 300 amp breaker trips, and a thing of smoke comes from the disconnect hanging off the breaker. Not believing it (or being somewhat amazed by it) I re-reset the tray breaker, then re-reset the buss breaker. Well Bang boom, flash. It was pretty amazing. Apparently when the disconnect outlet was installed on the conductors were never tightened correctly or one of them just loosened over time and a couple of the strands had popped back. Over time it had arced across, forming a carbon strip, that became conductive enough to finally trip the tray breaker. The final flash creating a perfect carbon short. I replaced the end, and kept the burned, melted end as a sourvernier, till I graduated.
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