From: eds1!compnect!frackit!dave@psuvax1.cs.psu.edu (Dave Ratcliffe)
Subject: Transmitters bite
Originator: wdp@gagme
Organization: Unknown
Date: Thu, 13 Aug 1992 21:52:40 GMT


Spotted this article in alt.folklore.urban. The topic swung into radio,
sort of, so I'll feed it into r.r.b.:

In article <H0TmoB8w164w@dogbox.acme.gen.nz>, dogbowl@dogbox.acme.gen.nz (dogbowl) writes:
> billn@hpcvaac.cv.hp.com (bill nelson) writes:
>In article <1992Jul18.175339.10396@newstand.syr.edu>,

> Ok. I want to know from the net people. What is the largest voltage shock
> you have ever received (and survived.) I am not talking about rewiring
> a light switch. I am talking about kissing the flyback transformer.

> a co=worker at a shortwave transitting station I was working at put his 
> hand on top of one of the small transmitters while he was tuneing it up.
> 
> The RF jumped about 1 foot to his wrist and grounded out thru his other 
> arm. Amazingly he survived, but he had very nasty burns right down to the 
> bone on one arm. Cooked flesh looks and smells disgusting!

I was Asst.  Engineer at a 5kw AM station in Altoona PA about
19(mumble-mumble).  Transmitter was a tube CCA and a REAL pig to work on. 
Chief Engineer (Jeff) was having a hellacious time getting the thing
working up to snuff after a major lightening strike at the tower farm (3
360' towers) which blew out the coax in 3 different places (pressurized
semi-rigid).  Anyhow, we were trying to get voltages in the PA cabinet
with a Sencore DVM.  He decided to do this in the afternoon while the
beast was on-line running the full 5kw into a single tower (daytime
non-directional). 

Using the kind of intelligence only a Chief Engineer
can muster he bypassed the safety interlocks on the back door (see, my
mama always told me clothspins were good for SOMEthing!) and proceeded
to start taking voltage readings on the inside of the front panel. To do
that he had to reach PAST the modulation transformer, only a few inches
above the spark-gap on the terminals. He was being VERY cautious in most
respects.... no jewelry, left hand behind his back, rubber soled shoes
on a rubber mat. I was about 3 feet to his left reading the DVM and
taking notes while he watched where he was putting his hand. Unfortunately
he forgot to watch where he was putting his arm and drew a healthy arc
from the point on the front panel he was testing, THROUGH his arm and
onto the spark-gap terminals on the modulation transformer. The station
was running a talk-show at the time so it could have been worse if the
modulation had been cooking up around the 97.5% we usually hung at with
music (yeah, compression was AWFUL but that's what the bosses wanted). 

The BANG blew him back from the transmitter (which merrily recycled 3
times from the surge) and into a cinder block wall 4 or 5 feet back. 
The remains of the Sencore probe wound up several feet away by the back
of the 1kw Gates standby transmitter and the DVM itself was sitting on
the floor with the display flashing something incomprehensible.  Jeff
shook his head, stood up and walked out the back door holding his right
arm and mumbling that he was alright.  When I caught up to him I noticed
his arm was a most remarkable shade of blue and he was busily shaking
it, still muttering that he was "OK".  When he finally sat down and we
could get a look at what happened to his arm we found a hole burned into
his index finger right where it was touching the screw on the
switchplate of the probe.  There was a nasty surface burn around the
hole and another hole back by his elbow with similar characteristics. 
Later (when the standby was on and the CCA was cold) we measured the
distance between the 2 holes and they corresponded with 2 flash marks in
the cabinet.  Sure enough he had gotten across the plate voltage for the
final and the modulation transformer. He was VERY lucky. The doctor
chewed him out, the station owner chewed him out, his girl friend chewed
him out and after about 2 weeks he was back to normal again EXCEPT for
some very minor trembling in that right arm. Count him as one of the
lucky ones. If he had had his left hand on the cabinet he could have
been dead. 

BTW, the Sencore DVM lived. The display was undamaged and turning it off
and back on cleared everything up. We buried the melted probe with
honors under the center tower and christened the gravesite with Iron
City beer and Kodiak Cream Ale. It was a touching ceremony :)

The moral of the story? Those interlocks are there for a REASON! USE
them!

[Moderator's Note: *** OUCH ***!]

-- 
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