The AM Forum

The Derb posted his worst crap out ever, in another thread. I thought it would be a great subject to get some in print for all eternity... ;D

Describe your worst nightmare here - something that actually happened to a piece of your gear...


Here's The Derb's:

"The worst crap out I ever had was with the Derb-100. The low level speech amp went positive feedback ballistic and crapped out every possible transformer in the modulator and speech amp and blew out some other HV stuff. Slab can vouch for this crap out. It was a king of all crap outs."


T

I have a DX-100B that had a major crap out a few years ago.  I turned the rig on and left the room for a few minutes.  I could smell something burning, and soon saw smoke.  The shack is on the second floor and I was downstairs.  I entered the shack to find the rig shut off and the place completely filled with smoke.  It turns out, the low voltage transformer, the filter choke, the driver transformer and the power tranformer all melted out and oozed all over the chassis and out the bottom on to the operating desk.  The only tranformer that survived was the modulation transformer.  Fortunaltely, I had a carcass with good iron for replacement.  I completely cleaned the chassis and rebuilt the entire rig.  You'd never know it happened.  It was a great learning experience as I caused the problem to begin with.  I solid stated the high and low voltage supplies and did not compensate for the added voltage.  I assume the 8 amp fuses took too long to blow, hence the meltdown.

Buddly said:
"My workbench in the basement had little fires all around the rig."

 ;D ;D  Buddly, you know you hit the jackpot when there's multiple fires going outside the rig... too funny!  That silver cleaner mistake could easily happen to me. Glad you mentioned it.


Jay said:
"It turns out, the low voltage transformer, the filter choke, the driver transformer and the power tranformer all melted out and oozed all over the chassis and out the bottom on to the operating desk." 

Gawd.. the worst smell ever. That transformer smell can linger for months!  I wonder if you figured out what actually started the problem after raising the HV and LV supplies with the solid state diodes? Sounds like a short somewhere that was just low enough to tax the transformers, but not enuff to blow the fuse right away. Once, I've had those brown terminal strips arcing over after solid stating a Ranger.

T

I think the day I had the Globe Chump on and the XYL called the fire department. My fire pager went off for my own house. That was a little hair raising.

In an attempt to reduce hum and improve my pwr supply, I replaced two 10 uf 2KV oil cans with two 23 uf 4KV oil cans..Switched the 1250V B+  and the 450V LV with each other...  mini lightning inside the 1625's and then the smoke came out from several places....  I measured the voltages and they were ok, so I replaced the (ex)working  ART-13 with the dog ART-13..... still not knowing I had reversed the B+ and LV ......   more lightning and smoke..... while it doesn't live up to the level of gloryfullness of crapouts, it must be up there in sheer moronisity....... the power supply works fine and now i have to disassemble at least one of the '13...  anyone got an auto tune crank??    klc

My most impressive zorch was when this college freshman built a SSB linear with a pair of 833s.
It was over in ten seconds.

1. Key down on wet night.
2. Cheesy end insulator on dipole arcs over to the string holding one end up in a tree.
3. String burns, half of inverted vee falls to ground.
4. VSWR goes through roof..Radio Shack coax line burns in half.
5. 833s light up like a flashbulb.
6. Holes burn through plates, shorting tubes out.
7. Tremendous surge of current in primary of pole pig plate transformer.
8. Breakers open.
9. Loud 'bang' in house as induction from #8 primary cable makes adjacent heating duct jump.
10. Lights out, smoke in air, neighbors wondering what the bright flash in their front yard was and (later) how a line was burned into their lawn, my dad going, "$%#$%!!!" and me pretending not to know anything.

What ya gonna do?

Good Topic!  The answer depends on the type of crap out :-)

Most Expensive:   1) Lightening hit a tower for a radio station for which I was chief engineer, and the tower fell down! :o
                         2) I installed a car radio in my friend's 1954 Ford using the original cotton covered wire, and the car burned up that night! :P

Most Dangerous:  1) back in 1974, the tank coil (an oatmeal box with the wire held in place with wax) in my rig caught fire and HUGE
                             flames spewed from out of the transmitter and hit the wooden, dry, attic celing immediately above me!   :(
                         2) An electrolytic capacitor blew up literally in my face, and I could have easily been blinded.  There was metal and :-*
                             junk on my face, but somehow it missed my eyes.  Thanks to God for that one!

Most Time Consuming:  I built a solid state pulse width modulator for a vacuum tube rig that took me several MONTHS to complete. I uttered
                            one word into the microphone, something arced and blew EVERY solid state device in the transmitter AND the 6 6DQ5s in
                            the RF final!!!  I was so bumbed out, I closed the door to the shack and actually didn't go back in for almost 2 years!  This
                            crap out spured me on to do the class E development and get away from high voltages. :'(

Most Stupid:           1)  The clip lead coming from my very hi-fi thordason mod transformer going to the RF amplifier fell off and the transformer
                              was destroyed due to an internal short circuit.  This was back in 1974.  Forced me to eventually develop a tube pulse
                              width modulator because good mod transformers were hard to find and expensive. ???
                            2) I was demonstrating something relating to a transmitter I had built, and accidentally connected a clip lead from a
                              35 volt high current supply to the OUTPUT and not the input of a 12v regulated supply.  Needless to say, the 12 volt
                              components did not last long! :-[

I once connected the AC line reversed to my Scott SLRM, which has a an AC/DC power supply wihere one of the sides of the circuit connects to the chassis.  It took out a big electrolytic cap that went off like an M80 with enough force to put a big bulge in the top of the radio's steel cabinet.  Never did get all the residue out of there....

Jury's still out on what took out my Yaesu FT100D  in the car a few weeks back.  Suspect it was a near lightning hiit.....keep your mobile antennas disconnected when you're are not using the rig at this time of year!.

Having an upright full size freezer comprssor crap out without warning while full of stuff was no fun either.....

I needed a quick fix to put my newly restored and converted Collins 20V-3 on the air. I was building a push to talk sequencer that would handle all aspects of transmit/receive safety but I wanted to be on the air for the Heavy Metal Rally in 2003. This was a self imposed deadline.

I went to a local ham fest and purchased a mil spec 24 volt Dow Key antenna relay. I plumbed in my favorite 75A-4 and went to work. I tested the circuits without a hitch and waited for the kickoff.

I made a few contacts and proudly introduced the new transmitter. I was asked a question by Mike N8ECR and launched into a long, windy reply.

I don't know if it was the smell or the flash that got my attention first. I spun left in my chair to see my 75A4 in smoke and flames.

The new (to me) Dow Key relay had failed. In fact one of the silver plated contacts on the clapper inside the relay had come loose and shorted the relay. I pumped mmm, errr, oh yeah 1500 watts PEP into the front end of the receiver.

I have to look back but it was only a month or two later when a fellow ham published a very good article regarding this exact failure mode in Electric Radio.

Needless to say Dow Key relays have NO place in my shack. The receiver lives with no trace and I am much wiser. The smell of burnt resistors and caps stayed in the house for a long time.

Great thread JJ. Hope the forehead is healing up.

Mike

Good idea to open those Dow Keys up periodically and check the condition of the relay contacts and cleas them.  They can crud up and come loose inside over time. I've had that happen to a couple of  mine.  Otherwise I've had good luck with Dow keys and found them to be very reliable.

Speaking of antenna relays, Mike, you reminded me of a time when one failed here with disasterous results.

I usually run open frame, DPDT,  24VDC "AC mains" type relays for all final antenna outputs. You know the type - they're about the size of an orange and use to be common at the flea markets.  I used one pole for the final output and the other pole for the driver/receiver. I've never had one break, even at QRO until this.

When using a single relay, double pole, to do the antenna switching, there is a path across the top of the relay where, if it arcs across poles, the final output sees the driver input. If the arc is big, it can easily get to the receiver contacts too. Some relays have poor HV isolation between poles. Look at it carefully before using it for QRO.

I was testing out a new 4X1 modulated by a pair. This rig was rather unique being mounted in clear, see-thru plexiglass in front of the operating position on a shelf. Tron was here and saw it in operation. Beautiful watching the three tubes. In addition, I sucked air out from the bottom of the air sub-chassis and blew it outside. A squirrel cage outside did the sucking. Cool in the summer running QRO.

Well, one day I noticed some instability and gave the neutralizing cap a twist from the front panel. The final took off and immediately drew a big flaming arc across the antenna relay. The two poles were now connected through a carbonized track of burned bakelite.

The 4X1 RF power was dumped into the input of my TS-930 Kenwood. The 930's receiver front end was toast as well as its solid state finals. It wiped out little relays, RF cans, transistors, etc. I sent it back to Kenwood and they said it was totaled. They said it appeared to be hit by lightning. It was the only rig I had at the time, so was yellafied.

I learned a good lesson. Now I use two separate relays - one big relay for the final's output and another smaller one for the driver/input antenna switching. The physical isolation really makes the difference in safety for the driver/receiver.

T

To date it has to be the three section plug-in Mallory electrolytic capacitor that let loose in the power supply for my Millen HF station. I switched on the filament voltage to let the transmitter warm up for a little 75 meter activity one Friday evening. I went upstairs to make a sandwich. I hadn't been in the kitchen more than five minutes when all of a suden my wife and I heard a loud BOOM!! I initially investigated the living room where the sound came from, thinking the cats had knocked over something. It suddenly dawned on me that the noise came from the basement! I ran down the stairs just in time to see a large mushroom cloud over my Millen station, so I quickly switched all power off. The three section plug-in Mallory cap in the power supply had detonated, turning itself into a tar-and-feather grenade spewing out goo and shreded paper in a small yet rather intense blast zone. Amazingly none of the tubes in the power supply were shattered! The shell of the cap had been shot into the cealing insulation and the guts of the device were sprayed all over the power supply and the wall behind it.  :o

My worst crapout happened about 40 years ago.  I was running a single 304-TL modulated by a pair of triode connected 813's, 2500v @ 400 mills on the final.  I suddenly started having a bad case of TVI.  Checked out everything in the station, and nothing seemed abnormal.  So I turned on the transmitter and went out on the roof to check the open wire line to see if something had come in contact with it and maybe was causing an arcing problem.

Found nothing amiss, so I came back in.  While I was out on the roof, the plate tuning condenser on the unattended transmitter had arced over.  The contacts on the overload relay were stuck and wouldn't let go.  A couple of plates in the tuning condenser literally had holes melted in them.  Worst of all, the 304-TL was ruined.  It wouldn't make power and badly downward modulated, and no amount of effort at rejuvenation was successful.  I fixed all the rest of the damage, but needed a new 304TL.  I knew an old ham across town who had some N.I.B. ones, so I called him and he said he would sell me one for 5 bucks.

I drove over to his house and picked up the tube.  On the way back, at a blind intersection that was just past the peak of a hill, I had a  head-on collision.  No-one was critically hurt,  but both cars were totalled and we all had cuts and bruises.

When I finally got home with the 304TL, I fired it up, and the damn thing was gassy!  One of those with separate grid pins coming out of the side of the envelope, connected together  with an exterier metal ring.  Lit up like an 866A.

I did manage to find another 304TL, but don't remember where.  I eventually replaced  the 304TL with a push-pull final that would take 810's or 8000's.

But the incredible string of unlikely mishaps - sudden unexplained TVI -  the tank cap arcing over the one time when I was out on the roof - stuck contacts on the overload relay that had functioned perfectly many times - the first car accident I ever had - the gassy 304TL...

I should have just stayed in bed that day.

Hmmm.....there have been so many, but I can't compare to most of youse guys! Many cases of components zorching and smoke escaping over the years, just hard to remember which was which.

Most recently when W1UJR was over and we were farting around with the big rig, trying to find out why it kept dumping the overload relay on voice peaks comes to mind. After dealing with a number of arc overs and trying to track it down, Bruce says 'let's turn the overload up a bit higher and try it'. We did, and as he advanced the audio gain, behind the glass window and screen of the PA section a huge light show ensued. Not your average arc, but fingers of lightning all over the place. Of course, the overload didn't trip off, but Bruce let go of the mic before anything detonated. I was already on the other side of the room, having been away from HV arcing long enough to reach panic mode more quickly. We were fortunate in this case not to zorch anything and tracked the final problem down to a loading issue.

Other than smoke-loss, the most recent event with damage resulting came about 9 years back when I plugged in a 516F-2 power supply socket to the back of a KWM-2A transceiver with the keyway broken off. The plug and chassis were marked with ink to indicate proper line up, but the plastic case on the socket has slipped just enough to make it interesting. Application of power was followed instantly by a *POPOP* sound, followed by smoke. Fortunately the damage was confined to a pair of ceramic discs and was easily repaired. Got a good jolt a few months back too, from a metal tube inserted wrong because of a broken/missing keyway. Wasn't even my rig, dammit!

I've been lucky (so far) in never having an electrolytic unload itself in my presence. The stories I've heard are more than enough. And I won't get into the self-inflicted damage since 'JJ already covered that in another thread... :)

Don/KYV said:
"I drove over to his house and picked up the tube.  On the way back, at a blind intersection that was just past the peak of a hill, I had a  head-on collision.  No-one was critically hurt,  but both cars were totalled and we all had cuts and bruises.
When I finally got home with the 304TL, I fired it up, and the damn thing was gassy!  "
--------------

Wow, that's a "collateral crapout" !   ;D

That tale of woe goes over the edge, Don. Unbelieveable how events can sometimes stack up in a row like that.  It's like having a mini-bear market in life.

I'm reading each of these posts carefully and not missing a word. The good thing about most is that there are things to be learned from other people's stories. It's neat to read the suspected cause of the crapout. One common thread seems to be human error with keyways, like yours Todd.  Others are simply components that decided to fail and take everybody around them with them, like a suicide bomber...

I have a few more to post, too, if the thread keeps going...

T

Jay's DX-100 crapout sounds just like what I found when I rebuilt Derb's DX100 after his crapout. The low level stages are always powered up, even when in standby mode. The class a load of those stages is used to keep the low voltage B+ supply bled down when in standby. If you remove all of those small bypass caps on the grids and plates of the audio stages they will sometimes break out into a regenerative ultrasonic oscillation and look out!


the best crapout that I had was when testing my 4X1 rig just after finishing up the build. I had it loaded up at around 700w of carrier into a dummy load and socked an "atomic yaaaeeelloo" into the mic with the audio really cranked up. I was watching the scope when I socked the yeeaalo and both of the 500pf doorknob DC blocking
caps from the plate to the final tank blew to bits. It sounded like a friggin blockbuster went off inside the cabinet and the room went dark. I jumped out of the chair and wondered what the hell happened. When I figgered out what happened I giggled as it was kind of a "good crapout" as it was making much more power than I anticipated.
I was just lucky that the flying debris from the caps didnt break the tube!

                                                           the Slab Bacon

Yo Slab,

Yep, it's good you mentioned those TV doorknob caps. As you know, almost every new builder has used them in an RF  high current QRO spot and had them blow up. Those old TV doorknobs are plentiful and easy to find. Good for voltage but not current.  But they are FB at ~200W AM rigs and less.

I've had luck with them in all choke bypass applications, and even occassionally as plate coupling caps, but they will blow up used in plate resonant circuits and as loading caps in QRO mode. It all depends upon the current shared with other caps, etc.

Back in '78, a friend of mine built a 4X1 linear. He didn't have a plate tuning cap, so made a stack of these doorknobs in series with a big switch and used a roller inductor as the L.  I warned him it would blow up, but he had to learn himself. It was such a pretty amp!  On the first tune up, BAAAM!!!! There was tan plasdick pieces blown all over the inside of his pretty cabinet. He's lucky he didn't puncture the tube.  I must admit I smiled... ;D

T

I burned up some 811(s) once.

I broke a vacume variable capacitor once. I forgot that it was in a box on top of the transmitter. I went to move the trannsmitter the box tipped the cap fell out and before I could do anything I heard that vacume implosion as the glass shattered. Never got to use it or anything.

Most rotten crap out I ever had was a selenium rectifier that went bad. It smelled horrible. Smelled like something was long dead and rotting away.

My worst crap out was the time I was working in a garage mounting a Firestone snow tire. The bead snapped when I had about 40 pounds of air in it. It lifted me off the ground and tossed me across the bay. I don't use Firestone to this day.

My worst QRO crap out was the first time I fired up the 4CX3000A after burner.
an arc flashed between the tube plate and rocky point resistor and looked like a small sun forming inside the rig. All contactors welded as the sun grew larger. I couldn't kill
the plate supply and it didn't need drive so turning that off didn't help either. Finally the 40 amp breaker in the panel blew and took her down. It was a very beat test jug but when I got my heart out of my wind pipe I found the tube split in two.
I was afraid of dropping the fil variac and hurting the tube.

Then there was the time I rented the 8 HP concrete finishing maching and had no idea how to use it. I got smarter after it picked me up and slammed against a wall the second time. Two friends almost pissed their pants trying not to laugh.

Back in 1985, a german friend (my mentor in this hobby) lend me a huge sp-600 ,his idea was " you have to hear and learn before transmit, one year latter I have my first license, but still I dont have any transmitter. suddenly  other ham friend gift to me a Viking Valiant, he use this transmitter as an auxilary chair in his shack! ;D...

Well, the TX have all the 6146 burn!, I get a new set, im install the new tubes, and Im just want be in the air ASAP!, so I turn on the TX, and well, a noticed a low output,  following the rules I put one hand in the pocket and the other bare hand in the neutralizer cap!!!

ohhh men...that was my first shock, since that moment I sufer a severe mental desease, called the old buszard maladie!

Special congratulations to all of you for still being alive after all that I've read on these pages.   Maybe we should quit working on this gear,  get some nice little transceivers and just talk with each other instead of continuing to create fireworks.  Down with the soldering irons and on to figuring out how to navigate menus.   One more thing.  Maybe Don needs to stop driving too.

Jon

PS:  Got across the HV of a Viking II at age 13 and still haven't forgotten it.  Recently put the output of the Class E into the input of the linear.   I keep the toasted pair of 3CX800A7's as a reminder.

That reminds me of the time I was working at Two Guys department store as a puny little teenager and was asked to buff the floor with one of those big single wheel floor buffers. That thing was uncontrollable and was chucking me around too before I finally got that hang of it.

And I'm sure this has happened to many.  You're  using a AC operated drill and you're drilling into something and the drill power switch is locked in the on position but you don't know it then the drill jams into whatever your drilling, is ripped out of your hand, starts winding up the power cord and you have no way of stopping it until it rips the plug out of the wall.

The worst rig crap out

About a year ago I decided to fire up the pre war HT-9 which had been dormant for too long. It was a nice summer day so I had the shack windows open. Mindful of the fact the 866s should be given a good ½ hour to come up to speed after being left off for 6 months+ , I continued to work on other projects while they vaporized to their hearts content.

After about ten minutes I began to hear what sounded like a sprnkler running outside (The rig is located under a window). I wondered why the XYL was watering the garden since we had plenty of rain that week.

I continued to hear the sound for another 15 minutes or so and began to get suspicious. Upon further investigation I found that it was coming from the HT-9. Opening the cover I discovered that the LV transformer (700V) was bubbling and was too hot to touch. I have no idea why there was not any smoke or flames and the fuse did not blow. I went up to the attic several weeks later to pull the transformer from the donor HT-9 and discovered the transformer in there was a replacement too. Must be a weak link in those rigs

The worst personal crap out

I was working on the Glob King 400 trying to get it to load better on 160.  It was a Sunday morning and the XYL had gone out on errands leaving me with the then 5 and 3 year old daughters who were playing down the hall.

Deciding I needed more capacitance I put a variable in parallel with the exiting cap to see what would happen. While leaning on the case, I grabbed the shaft to turn it with my other hand while observing what would happen to the plate current.

Well what happened is the current went trough me, throwing me across the room on to the floor. I lay on the floor dizzy and seriously wondering if I was going to come out of this. My daughters hearing the “boom” ran down the hall in panic to check on me. Not swishing to calm them I explained that I was tired and was laying on the floor to take a little nap……..

I was able to resolve the problem; I stayed on 75 with it

Not Amateur, but I was working on a Collins 820D Am transmitter for a station and had it on a dummy load. I had the Loni Anderson look alike receptionist hold a neon bulb and as a joke, i keyed up the transmitter and it lit the light, which she dropped, and all the neon dust was sucked into the transmitter.  Took me 5 hours of cleaning to fix that FUBAR. And NO I didn't get lucky.

I have a couple. The worst was a transformer in a power supply that I built for a military mule pack radio, a BC-654 that I picked up at Hosstraders. The thing had been modified and the schematic was tough to follow too -positive ground crap and so on. Anyway I had a slow burn short going that overheated the transformer. Ka BOOM! and hiSS! Noxious smoke and hot black tar eveywhere. Yuk and it was a mess to clean up. The BC-654 went back to Deerfield the next year.

PCB city I imagine. I got a rare leukemia three years ago and you have to wonder! I beat it though.

Another good one was just last year when I had a bias cap in my Marauder short out causing the bias to go away on a solid stated 800 VDC supply which serviced the pair of 6146's. What an exciting orange and blue light show. At least the fun was confined to the cage. All fixed now.

Finally when I was making my own circuit boards I was using Ferric Chloride to etch the boards in a sink (of course). I decided to clean up with Comet. Bad Idea.

Mike WU2D

Right on the neon dust.  ROFL!  Should have read dust from the neon light. This was in 1971, so it had the 5-500 tubes.  I understand it got reworked in the early 90's but not by me.   Saw the receptionist again in 1978 and she was equal in mass with the transmitter. 

BTW, Harold Smith W4PKW in Pensacola has an 820D in his garage on the "to do" list. Not in bad shape for its age.  73!   

Yeppers, selenium had a real nasty smell.  If you ever got a whif, you'd never want another. Hated the smell of burning bakelite too.  I worked with a few slow learners...

Worked with a guy in new Orleans years ago without a sense of smell.  Saw him work on a Marine AM rig power supply and the transformer was belching smoke like a coal locomotive.  Since his back was turned and he could not smell, he was fat, dumb, and happy.  I almost ran over him to shut the power off.  He just kept saying, "Whus wrong? Whus wrong?".  Used to do the hollow spaghetti lead under the workbench rubber mat thru a small hole under a piece of gear he was working on.  He'd turn it on and I'd blow cigar smoke up thru the tube out from under his "patient". 

Carl,
You remind me of my Dad's worst crap out. He tested jet engines but decided to replace the picture tube in the old GE. His tech buddies wrote him a procedure and it looked easy. Step 1 discharge the anode. He did it about 3 times. no more sparks. He grabbed the wire and came out of the back of the set like he was kicked by a mule as my brother and I watched. We thought he was dead. Slammed against the wall with his eyes spinning. He recovered and went on with the repair. It was one of those priceless childhood things....

 ;D ;D ;D

I never heard that one before!  Great fun in a shop of technicians.  I use to work in a few Motorola 2-way shops in the 70's and can just imagine the laughs...

T

I'm sure you meant to say a fluorescent bulb.. I can't imagine a tiny neon bulb causing much trouble if dropped.  ;D ;D  "LOOK OUT! SHE'S GONNA BLOW!!!"

Not my crapout but a good story nonetheless, related to our contracting and procurement class by a retired government procurement official.

That gentleman was the procurement official for one of the US Government research labs.  They had a hugeassed wind tunnel at the facility that was powered by a big radial airplane engine.  Anyway, one day a painting contractor left a ladder in the wind tunnel.  The next day they fired it up to do some testing and the ladder was of course sucked into the engine, but not before bouncing all around the room and wrecking the airframe under test, the test instrumenation, the intake, and the engine.  It essentially destroyed the entire facility which had to be rebuilt at the cost of millions of dollars as well as delaying a critical defense program.

I think the moral of that story was what to do when a contractor screws up.

I cringe when a rock or a big stick goes through my lawn mower but a ladder going through a prop that must have been something to see but can't be anything like this. http://www.youtube.com/watch?v=2ABdcrnIV40

I'm just curious why anyone didn't check the area to ensure it was clear before firing up the wind tunnel.

there was an american airlines stew who commited suicide by jumping into one when it was winding up....

I can't understand how someone could live after going through the blades of a jet turbine???  Maybe he just got stuck at the opening and they shut it down...

T

one lucky SOB!!  When I worked at FED EX there was an employee who got into the prop of a Fokker F-27...

They used to have us put Safety cones in front of the engines on the Airbus, they were only about 18 inches of the ground and when they taxi you could see them suck up dust in a mini tornado.

I don't know how true this is but I read somewhere that the F-117 when cruising nearly 50% of it's forward motion is caused by the intake suction of it's engines and that prior to running down a runway the runway has be cleared of all small debris as the engines will suck it up.

Yeppers!  We had Sorensen bench 12vDC supplies. They were on a shelf below the workbench in a corner.  Great supplies.  If you shorted the power leads, they would just clamp down and pop a breaker switch. You had to crawl under the bench to reset.  12v terminals at each workbench was the output for the Techs.

I would take my power leads and watch another tech work.  When he went to flip on the power on a 12v rig, I'd touch my leads together and pop the common breaker.   Thinking his equipment had a short, he's crawl under the bench, reset the breaker, then ohm out a few things.  Of course he would not find a short, work up the courage to turn on the test radio and I would short my leads together and pop the breaker.

I did this to one poor guy 5 times.  He only figured it out when i could contain my laughter no more.  He got me back.  I was working on an AM Marine radio reciever and was using a 455 osc. to go through the IF.  I had to turn up the volume to hear the tone.  Every time I'd put my ear close to hear, the radio would emit a terrible squak.  Finally saw him laughing.  He had taken wire and made a giant coil under my rubber mat (under my radio) and had it extended over to to his bench and coupled into the finals of a SSB unit he had on a dummy load.  When I'd but my ear close to the AM rx, he'd key up the SSB rig and blow quietly into the mike.

But I got the LAST laugh.  He chuckled so much he had to go to the men's room.  While he was gone, I undid the SSB rig from the dummy load and used a piece of coax with battery jumper cable clamps to jumper the output to his metal work stool.  He came out and saw me bent over my radio and just HAD to give me a big whistle.  Yep.  He whistled then yelled as the RF singed his rear end.

In a perfect whirl, all jets should probably be required to have internal automatic protective screens that slide over the engine intakes once they land, for human protection. But that's more added weight, etc.

I've often wondered why mufflers weren't required on all piston powered airplanes. They come over the house here and I can hear them for miles, just like a car with a blown muffler...  :)   But, it's all about getting max power out of the engine with minimum back pressure, I guess. The end result is better safety when trying to clear those power lines on take-off.

T

The A-7(?) guy ended up on the compressor cone and didn't get into the blades.. someone had the jockey kill the engine.. dis was on local TV in the last week or so. The flame seen was his clothes being burnt...

In school, each lab table was controlled by an individual breaker. After the student started his work, the Dept. Head went and triped the breaker... Greate fun... The real funner part was that there was a big red indicator bulb (7.5Watts?) at the lab station power supply, and usally the voltmeter was placed all over the circuit looking for the problem.. nobody noticed the lack of the brigh red glowing orb directly in front of the face.... I guess the victum  learned to always check power before troubleshooting.....
  klc

Bob,
All high value mil jets have teams of guys who do FOD hunts prior to them coming out of the hanger. The F117A has two doors on top of the inlets that are spring loaded. On take off the doors are sucked open to allow additional air flow into the engines because there isn't enough ram air to feed them. I don't think the suck thing is valid since these doors are on top.
I was in a  737 once and saw a rock get sucked off the ground right into the motor. My dad tested many JT8s so gave him a call as soon as I got home ant told him about this two inch rock. I was sitting just ahead of the wing and expected it to blow. My Dad assured me the motor was fine as long as it doesn't go down the core.
Tom Vu a screen on the front of a jet motor would melt with the air friction.
The A7 sucked many Navy guys down the tunnel of death. The front fins on the first stage were sharp and small.

Hi Frank,
OK on the F-117A.  Maybe it was some other aircraft I'm thinking of or maybe it's just BS altogether.  In any event the suction is incredible nonetheless and be able to pick a person right off their feet. 

There was another video floating around on the net not to long ago where a man got sucked into a Continental Airlines engine.  You see him get sucked in and nothing but red and flame come out the back of the engine. It wasn't a pretty site.

Bob,
Like any motor a jet uses ram air to aid in compression so there may be some flight conditions here it may be sucking the plane forward when the motor is wide open and the plane is going slow. The F117A the doors on top would just open.
I had a friend in the Navy who saw a couple guys get sucked off the deck.
He actually told me about guys who were able to hang on and come out the front.
That front set of blades on that alison are small and sharp looking.
My Dad sent many a chicken to the rotating deboner/cooker.

Frank said:
Been there and saw that Frank. The A-7's and F-14 were notorius for lifting up the newbie on the flight deck. Usually, they would wind up FODing out the engine with their headgear and any thing attached to their flight deck vest. It would really piss off the pilot and the jet mechs. Those GE-110's(?) were a bitch from what they told me. Intrestingly though, when they would test the engines in the test bed on the fantail, they would have to notify the navigation bridge because they could cause the ship to go off course!

When I was in school the electronics lab installed a whole slew of new benches with bench power supplies. Each supply had a red pilot light to indicate when it was turned on. It was really just a white bulb with a screw over red cover.  Afdter a couple weeks the benches started to malfunction.  The second you tried to turn one on the breaked would pop. Week after week more and more bench power supplies became inoperable due to this problem. The instructor thought the supplies were defective and prone to developing internal shorts thyat prevented them from operating. And still more and more became inoperable. Then one day someone just happened to take the red cover off of one of the pilot lights and noticed that inside the bulb was removed and a wad of aluminum foil was stuffed into the bulb socket. That was the internet short. Apparently some joker decided it would be funny to stuff foil into the sockets. Every week or so he'd stuff a couple more benches. I'd imagine he got a good laugh out of it. It took a while for anyone to figure it out. Once the foil was removed each bench worked fine...minus the pilot lamp which was removed,.