Wow, kinda quiet around here....
What happened to all the lively conversations? I was enjoying hearing
everyone's battle stories of their RF burns, etc.
I think one of my RF burns that hurt the worst was gotten from when I
worked at Motorola.
I was doing some system testing of some of our 800 MHz cellular feed
forward amplifiers. These amplifiers have a pilot tone signal that is
typically cancelled out in the IM correction process but still exists.
And if the PA was just fired up and no correction applied, this tone
would not be cancelled but rather be sent out of the PA and into the
system - unbeknowns to me!
Well, I fired up the entire base station. No transceivers were keyed and
so no signal was being output or so I thought. I was feeling around on
top of our distribution frame for a connector or something. The output
antenna connectors are 7/16 DIN jobbies that are really large. My index
finger and another finger touched the center conductor of the 7/16 jack
and the outer ground ring. I immediately got a nice sizzle. When I
pulled my finger down, I could see the structure of the 7/16 connector
branded into my finger! It hurt like the dickens. I still remember the
feeling.
Funny thing is, this was probably only about 150 Watts, but at 800 MHz,
that's quite a bit.
Also have had the good ole RF burns on the lips from the microphone in a
"hot" station setup as well as a real good one in college I got on my
hand from just touching the chrome on the microphone!
Sadly, I do know engineers who have never had the fun of an RF burn.
IMHO, you ain't a real RF engineer until you had one! The saddest thing
though is those engineers who built everything in college on proto boards
and don't know which end of a soldering iron to pick up (I had a
professor in college who when I interviewed for an antenna tech position
in his lab literally ask me if I knew how to use a soldering iron!).
And now days I have engineers who don't want to look at a small signal
amplifier unless it is matched to 50 Ohms in and out and runs on positive
supply only!
It's a sad world!
73,
Jon
KE9NA
--------------------------------------------------------------------------
Jon Ogden
jono@enteract.com
www.qsl.net/ke9na
"A life lived in fear is a life half lived."
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|