[Elecraft] QRO precautions ??

[Ron D'Eau Claire]

Bill, K3UJ wrote:

With the possible eminent presentation of a VERY QRO amplifier to  the 
Elecraft family, there is certain to be a number of us, with only  QRP
experience, 
jumping in and "playing" with gobs of RF energy for the very  first time.
Let's 
hear it from those with experience, some  do's, don'ts and caveats that go 
along with running the legal limit. I  hate learning stuff the hard way...

-----------------------------------------

I'd start with the observation that any part of the antenna circuit of a QRO
rig should be treated with the same respect you'd give the inside of your
household mains circuit breaker box.

The RF from a QRO amplifier won't likely kill you like touching the
terminals behind the safety cover of a circuit-breaker box will, but if you
get onto high voltage RF you may wish you were dead. 

The pain of serious RF burns is deep and long-lasting. Permanent nerve
damage is not unusual. 

Once I was working with a guy installing a large, self-supporting antenna on
a ship when he got a burn on his hand from induced RF from a nearby
broadcast station. We were using a container crane to position the antenna
for bolting to the ship. I was on the ship and he was "riding the crane"
with the antenna. When he reached across to position to base so I could drop
the bolts in place, I saw the glow of an RF arc between the brass antenna
base and the ship. He let out a howl that would have done the Wolf-man
proud. I later figured out that the 200-foot high container crane, grounded
at its base on it's metal tracks to ensure workers are absolutely safe from
electrical shock, formed a giant loop antenna with the ship sitting in salt
water. We were only a few hundred meters from the broadcast towers. It made
a black mark about two inches long on his palm in a fraction of a second. 

He was in such severe pain for several weeks that is was very difficult to
use that hand at all.

Remember, that was just the induced RF from a nearby antenna. No direct
connection at all. Several hundred watts from a Ham rig can be at least as
destructive if you touch it.  

Also, I've seen arcs 6 inches and longer erupt from high-impedance points of
a kilowatt transmitter antenna system across a dirty insulator. They not
only pose a serious injury hazard, they can and will start fires. Temporary
or indoor antennas are no place for QRO power levels. 

Like all high voltages the voltages resulting from high RF power levels need
not be dangerous or harmful if treated with respect. Good insulators, decent
distance between people and the antenna, and good safety procedures when
working around the equipment make a kilowatt no more dangerous than QRP. 

Ron AC7AC