A RUDE Awakening ! ! !

[k7yoo]

I wonder if that choke is what was eating your plate iron. I remember going through intermittent HV crapouts on one of my KWS1's before I finally found out that the choke was leaking and arcing to ground (a common problem on them) I figured it out before I lost the plate iron. I have a spare Stick out of one of my bcast xmitter salvage episodes--Shall I Stick it in the Mail? I think it is a Continental.
Skip

[K5UJ]

I wouldn't rely upon that resistor to stay together after a single use... I put one together with a higher ohmage myself...

You mean the 13 ohm w.w. in my chicken stick or something else?  not sure which R you talking about.  I guess I used the low value because the service line in-rush resistors are around 10 ohms but of course the line v. is very low compared to what's on a charged filter cap.  I guess it should be somewhere around 500, 1000,  2000 ohms.  For my p.s. 2K would discharge about 2A. I will root around and find another resistor amongst my hamfest goodies.

[W2PFY]

Sorry to hear about that Frank. I too have been hit. As mike said, a Jesus stick is the way to go. The wire on the stick should be insulated. The end that connects to the chassis should be bolted on. No crimp connections on the lug that connects it unless it's soldered!!

[steve_qix]

All I can say is WOW !!!!! Sure glad it didn't go through something major - not a good time for a funeral.

Thank God it happened the way it did.

Even though there's only 130VDC in the class E rigs, I'm careful has heck.  I too have had one of your experiences, Frank, and it changed me forever.

[KA3VID]

Glad to hear your FB OM.Now you know why I was sceeered to neutralize the 6146's on my 530 !

[Dave KA2J]

Thanks for sharing Frank.  Your comments may well save a life.  I know I will be more careful now!

[WU2D]

Holy Hornswaggles Frank! Good thing you weren't wearing Brent's crotchless chaps...

[W1IA]

WOW!! Thank God your ok Frank

Brent

[Opcom]

What are the specs and size of the choke Frank?

Most here are only 500mA but maybe there is one around @ some of my friends.. But I guess that size rig uses a >1A choke. There is a nice 3.5A 3H 7500V choke at the Black Hole, probably from the 5KW RCA rig.

What does it even cost to buy a new 1A choke any more now? Maybe it is time to think about the 30-60 year old chokes many of us treasure and use. They are getting older, corrosion my be taking its toll, etc. Not to discard them, but to figure out some way to safety the choke if it opens. What fails overvoltage shorted? 100V disc capacitors were mentioned in an old radio book for use on 1200V circuits. Silicon rectifiers?  Also, how to have a telltale the choke has opened? A telltale for the cap being charged might be a string of 1m resistors and a neon lamp.

[KB2WIG]

Maybee its time to rebuild some of the older iron.....  dubya zee ?

klc

[N0WVA]

I never got tied in to that much voltage/current. I did get hit rather hard with 850 volts or so when I had my old HT32B Halliscratchers rig. One hand was holding open the flip up lid and the other hand reached down to pull off a plate connector. That one had to go right across the ticker. Good thing I was young at the time.

Glad your still here.

[k4kyv]

Actually, "bleeder" resistor is a misnomer.  Its purpose is to maintain a minimum  load on the power supply to avoid excessive voltage surge under light or no load.  It should not be counted on to bleed the filter caps when the supply is turned off and that was never intended to be its primary purpose.

[W1VD]

Thanks for the refresher course Frank. Glad you're okay.

As far as the 'mini bleeder' Tom JJ suggests it might be a good idea to avoid carbon film and metal film resistors. I've seen a number of unexplained failures (open) when these resistors are used in high voltage applications - even when used within their ratings. Perhaps the problem stems from unexpected surges. Whatever the reason, I haven't noticed this with carbon comps. 

[W1ATR]

Thank God your OK man. It could have been a lot worse. Years ago, a close friend of mine got bit hard from one of these TMC 750's (3000V no load) from his hand to his knee as he knelt down to adjust the modder idle current. He got lucky because he wasnt 'grabbing' anything, and just fell away from the transmitter. He was totally paralyzed from the neck down for about 10 minutes. He tells me this story every once and a while probably with the purpose of keeping me scared. I check everything now EACH AND EVERY TIME i stick my hands on a HV suckply. There was a story floating around years ago about an old timer that got zinged from a Valiant he was working on. As it goes, his wife called him upstairs for dinner some time after that, and while eating, he fell off the chair dead.

Staying scared of what you can't see hiding in these supplies will keep you alive.

[The Slab Bacon]

thanks, Guys!! I still think the saving grace of it all is that I got ALL of it just through my right hand only. Dont get me wrong, it hurt like hell, but I didnt get any of it through my body. This time I didnt feel any heart palpitations or anything like that. It did scare the livin szht out of me when I saw that arc go to my thumb and heard the loud crack. after cleaning out my shorts and regaining my composure
(about 10 minutes) I had the meter probes back in my hands and continued on troubleshooting. (By the previous symptoms, I thought I fried out the plate choke) Who'd of ever thunk the filter choke failed open? ?

But like Patrick said, it might just be time to thoroughly examine some of this aincient Iron that we are using and covet so dearly. I have never had a choke fail open before. I have seen plenty of them with insulation failures short to ground, but never totally open. I think mine just opened up from the current load of the 4X1 plate. (about 1/2A @ carrier) It was a 1/2A choke that was easily 60+ years old, potted or not. Being potted, I always felt that it was much less suceptable to moisture damage from age and time. Not to mention that that I HI-POT tested it to 3500VAC about 10 months ago (while changing out the plate iron) with absolutely no sign of any leakage. (I usually test anything HV with a HI-POT tester before installing it)

Like I said before, I posted my misfortune as a reminder so others would be wary and not repeat my misfortune. Like I have said many times to many people: "High voltage has absolutely no respect for you, so you have got to respect it! ! ! ! ! ! "
Or like my parents used to say just before they were goin to wail the tar out of me:
"When you dont listen, you gotta feel!"

After crunching a few numbas, I think something around 5 meg for each cap safety bleeder resistor is in order for each oil cap. I allready have 2 50K 225W large dogbones in series for the main bleeders.

Holy Hornswaggles Frank! Good thing you weren't wearing Brent's crotchless chaps...

NOW, THATS QUITE A MESSAGE! ! ! ! ! !    

As far as the wound goes, I will keep a close eye on it as I am a bit succeptable to infections due to the fact that I am diabetic and have liver disease as well. But.............I'm a tough old bird, and it will take a lot more than this to get me down.

                                                             The Slab Bacon

[The Slab Bacon]

WOW!! Thank God your ok Frank

Brent

Brent,
        It blew right after I signed with you, friday evening. After you tied the ribbons on it, I gave the PTT a quick click, click and it went bang and blew the primary fuse!

Holy Hornswaggles Frank! Good thing you weren't wearing Brent's crotchless chaps...

Hmmmmmmmm...................I wonder if he has crotchless panties to match?   

[WD8BIL]

Hmmmmmmmm...................I wonder if he has crotchless panties to match?   

Some questions are best left un-axed!!!

[Superhet66]

Woof, a thorough reminder  

I work with hot line V. too often and pay with a chomp once in a while. I still work with one hand ( when I can ) but I'm thinking it's a bad habit now that I'm probing around HV again. I'll heed the Slab Bacon warning.

My only real hit was from a rcvr. B+ > chassis in my damp basment bedroom as a kid.
I was contorted and trying to lift every thing onto a new shelf and I couldn't get out from under the mess of leads as it zzipped me. I was 11 or 12 and didn't know from grounds on a cheap, bare boned, tube, SW chassis.   

If my parents knew the hazardous situations I put my self in as a kid they would have chained me up.
                                   Glad your all right OM.

[steve_qix]

Didn't the chief engineer of WKBW get killed back in either the '60s or '70s - and then there was old Ralph W2WME who got it while working on a linear, I beleve.  So glad Frank wasn't another statistic.

[w3jn]

Wow!  Thank God you're OK Frank.   I don't wanna hafta travel back to the states for a funeral!

[W3GMS]

Steve....
I sure remember Ralph.  We were all surprised when he got hit and did not survive.  I think he was working on an SB-220 linear amp at the time. 

I am not sure about WKBW chief engineer. 

Working with HV is a lot like tower climbing.  If you take short cuts it will get you.  That true of a lot of things.  Look at boating and aircraft accidents.   We tend to get very comfortable with things we work around. 

My Dad into his 80's would put the extension latter up and re-shingle the roof.  Then one day he took a shortcut and fell while doing something much easier.  He crushed all the vertebras in his back.  Struggled with the pain for several years and then gave up.  He was dead a month later.

Regards,
Joe, W3GMS   

[ke7trp]

wow.. Glad your ok! 

C

[KA2DZT]

Yo Frank,

Good thing you're OK,  sure would hate for you to never hear my imaginary 813   Having said that,  at the rate I'm building the 813,  you'll be with us for a long time.  I have also noted that you have had some other health issues over these past months.  I wish you well on all.

A HV choke opening up like that is not too common.  It probably shorted to ground internally.  The short fused open the winding, most likely near the terminals.  One reason I don't like potted chokes or xfmrs.  They develop carbon shorts through the potting tar, usually near the terminals.

You being zapped by the input cap is a very good reason to not use cap input filters.  The choke opening up left the input cap fully charged with no bleeder current.  You can always have separate bleeder resistors across each cap.

Don't short circuit yourself,  I'll talk to you on 75M.

Fred,  KA2DZT

[The Slab Bacon]

Yo Frank,
You being zapped by the input cap is a very good reason to not use cap input filters.  The choke opening up left the input cap fully charged with no bleeder current.  You can always have separate bleeder resistors across each cap.

Don't short circuit yourself,  I'll talk to you on 75M.

Fred,  KA2DZT

Fred,
       I would not have used cap inpoot if I didnt need it to get the voltage I wanted to keep the 4-1000 happy. Sometimes you just gotta do what you gotta do. I like to have as much "fire in the wire" as I can.

I could not be happy making others have to listen to my piss-weak 51watt signal.
Remember the first rule of the piss-weaker: "the weaker they are, the longer they talk"

BANG! ! !  LOOKIE HERE, SQUASHED JUST LIKE A BUG      


Hi, Fred    

(I probably wont live long enough to ever hear the "imaginary 813 rig")

[The Slab Bacon]

Wow!  Thank God you're OK Frank.   I don't wanna hafta travel back to the states for a funeral!

Nah, we just need you back here to have some more big signals on the WFD net