I just bought an Icom PW-1 (1kW) amplifier. My concern is whether or
not I could potentially burn out the front end of other receivers attached
to
nearby antennas. My tower clears the roof line of the house by about 10'.
The 6 band HF beam is 1' above the thrust bearing (top of tower), and
approximately 8' above the beam is the triband vertical (at the very top of
the mast.) That said, there will definitely be a significant RF field above
and
below the beam, as well as to the obvious front and back of the beam.

So, is there a danger of inducing destructive voltages to the vertical
above? What about other antennas on my roof near the tower?

My beam is well above the roof line, but as I have two tripods on the roof,
each with assorted verticals and beams {6m - 70cm LogP, two discones, a 902
yagi, and 902 vertical, and a 220MHz vertical.) These are each 25 to 30
feet away from the HF beam. There's also a distorted G5RV (aka: has a 90
degree turn near the end of the long leg as to stay on the property) running
off the roof to some trees along the back fence.

So you see my concern about having a 1KW RF source in proximity to all the
other antennas. Any other kilowatters out there with some experience or
advice
to share?

'73,
Pat, VE3PMK

It won't melt them even if you connect the antennas together with wire.

Butch KF5DE

Pat wrote:
I just bought an Icom PW-1 (1kW) amplifier. My concern is whether or
not I could potentially burn out the front end of other receivers attached
to
nearby antennas. My tower clears the roof line of the house by about 10'.
The 6 band HF beam is 1' above the thrust bearing (top of tower), and
approximately 8' above the beam is the triband vertical (at the very top of
the mast.) That said, there will definitely be a significant RF field above
and
below the beam, as well as to the obvious front and back of the beam.

So, is there a danger of inducing destructive voltages to the vertical
above? What about other antennas on my roof near the tower?

My beam is well above the roof line, but as I have two tripods on the roof,
each with assorted verticals and beams {6m - 70cm LogP, two discones, a 902
yagi, and 902 vertical, and a 220MHz vertical.) These are each 25 to 30
feet away from the HF beam. There's also a distorted G5RV (aka: has a 90
degree turn near the end of the long leg as to stay on the property) running
off the roof to some trees along the back fence.

So you see my concern about having a 1KW RF source in proximity to all the
other antennas. Any other kilowatters out there with some experience or
advice
to share?

'73,
Pat, VE3PMK

So you see my concern about having a 1KW RF source in proximity to all
the
other antennas. Any other kilowatters out there with some experience or
advice to share?

I've wondered the same, and have in fact heard of people
frying the front ends of radios from that...But I think it depends
on the radio, the difference in freq's, etc...I've had two meter
rigs hooked to ground planes, and yagis, that are on the same
mast as my dipoles, and I never had any trouble...But thats not
to say someone else could have a problem. The earlier IC -706's
had an issue with trace burning, or something along those lines,
from the RF from one band, causing a problem through the other
side of the radio. "HF". I think it was the VHF melting the HF trace,
but not sure...But they fixed it on later models...I *think* mine is
one
of the later "fixed" ones...I've never had that problem..Anyway, if
it really made me nervous, I'd unhook the other radio. I did that
sometimes, when I was really browning the food on HF. Even if in
a semi null, the FS is going to be high, at that short distance. MK

BTW...Many/most radios are probably semi protected..
IE: back to back diodes on the front end, bulbs, etc...
But.....Still something to consider if the power is really
high...MK

In article .com,
wrote:

So you see my concern about having a 1KW RF source in proximity to all
the
other antennas. Any other kilowatters out there with some experience or
advice to share?

I've wondered the same, and have in fact heard of people
frying the front ends of radios from that...But I think it depends
on the radio, the difference in freq's, etc...

I just read an article in the ARRL Antenna Compendium #3 by a guy who
used to live (and work HF) on the grounds of a big AM/shortwave
broadcasting farm in Quito. The RF field strengths were several times
what the FCC now allows for human exposure.

He had some serious RFI problems. One amateur near him put up a
20-meter quad, hooked it up, and smoke came out of the receiver... it
burned the coils. He put up a 40-meter dipole, and found that it
could light up a 100-watt bulb!

His article has a number of suggestions for people suffering
high-energy RFI problems... might be worth your reading.

For the situation where the high-power source and the vulnerable
equipment are on greatly different bands (e.g. kilowatt HF and a
2-meter antenna) I think you're at substantially lower risk. It might
be worth your while to gin up a simple high-pass filter for the
two-meter gear. A quickie approach would be to buy a commercial
2-meter/HF diplexor, and leave the HF side unconnected (or terminate
it in a 50-ohm dummy load). Maybe add some ferrite chokes to your
2-meter feedline, just to discourage it from acting as an HF antenna
and bringing RF back into the shack on its braid.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Hi Pat, short answer is yes, especially for the other shortwave radios.
Invest in some coax switches to disconnect unused receivers.
VHF/UHF radios might be OK, but a bandpass filter would help to isolate
them.

Also, any RX that has diode protection in its front end will turn into a
great harmonic generator when blasted with a big antenna signal.

73,
John


"Pat" wrote in message
.. .
I just bought an Icom PW-1 (1kW) amplifier. My concern is whether or
not I could potentially burn out the front end of other receivers attached
to

"Pat" wrote in message
.. .
I just bought an Icom PW-1 (1kW) amplifier. My concern is whether or
not I could potentially burn out the front end of other receivers attached
to
nearby antennas. My tower clears the roof line of the house by about 10'.
The 6 band HF beam is 1' above the thrust bearing (top of tower), and
approximately 8' above the beam is the triband vertical (at the very top
of
the mast.) That said, there will definitely be a significant RF field
above
and
below the beam, as well as to the obvious front and back of the beam.

So, is there a danger of inducing destructive voltages to the vertical
above? What about other antennas on my roof near the tower?

My beam is well above the roof line, but as I have two tripods on the
roof,
each with assorted verticals and beams {6m - 70cm LogP, two discones, a
902
yagi, and 902 vertical, and a 220MHz vertical.) These are each 25 to 30
feet away from the HF beam. There's also a distorted G5RV (aka: has a 90
degree turn near the end of the long leg as to stay on the property)
running
off the roof to some trees along the back fence.

So you see my concern about having a 1KW RF source in proximity to all the
other antennas. Any other kilowatters out there with some experience or
advice
to share?

'73,
Pat, VE3PMK



Pat,
This is probably worst case, but after installing a new 75 m antenna, I
measured the power picked up by the old one, broadside, and about 30 feet
apart. Got 10 W at the end of the feedline. Unfortunately, I can't remember
if I was running 100W or a KW at the time, but lean towards the 100W.

On the other hand, I have a tribander with a 2m beam 4 feet above it, and a
6m beam 4 feet above the 2. No problems running a KW on HF and 375W on 6. If
I were to run a KW on 10m, and turn the 6 m radio to 10 also, that would be
a different matter. As it is, there is a Bencher 32 MHz LPF at the output of
the HF amp.

Tam/WB2TT