On Wed, 19 Apr 2006 18:27:22 GMT, Bruce in Alaska
wrote:

In article LPr1g.366$PL2.236@dukeread03, brad
wrote:

Al Thomason wrote:
How concerned do I need to be about an Air Horn (Buell, 17/23") near a
SSB antenna? The location I am going to put the whip in has an air
horn perhaps 1' forward. Should I relocate the horn to the other
side?

Thank you
-al-


I can foresee two possible issues. The first is that the air horn might
interfere with the SWR of the antenna or have an effect on its radiation
pattern. Personally I wouldn't be all that worried... there's tons of
stuff on a boat that has the potential to cause those problems. I doubt
if a horn will make that much of a difference.

The second issue has to do with RFI. I would not be surprised at all if
while transmitting with the ssb antenna you generate all sorts of noise
coming out of the horn. However, that can happen regardless of where on
the boat you place the horn. If it becomes annoying you can always try
to filter out the noise at the horn side.

Maybe you can explain just how the OP's "AIR HORN" would be suseptable
to RF Interference from a MF/HF Antenna/Radio system mounted in
proximity to the antenna. All the radiomen of the newsgroup would
certainly like to understand this amazing phenominon.
Then again, after you get done figuring that out, could you kindly
explain, just how the presence of a, presumably Grounded, "Air Horn"
would have any measureable effect on the SWR of an MF/HF Antenna
System that is driven by an AutoTuner, that would take into account any
Near Field Grounded Element, every time the AutoTuner retuned the
antenna at a Frequency change? The Capacity of a Grounded Element
One Foot away from the base of an MF/HF Antenna would be, at the
maximum, maybe 1 or 2 PicoFarads, which at MF, and even the High HF
Frequencies, would be insignificant compared to the other elements in the
Antenna Mounting Structures, and the active elements in the autotuner
itself. Maybe Lynn, Larry, or maybe even Gary S. can chime in with
"further Light and Knowledge", on the above issues.

Bruce in alaska

Well, you know Bruce; with all that air around the horn being heated
by the RF in close proximity there is bound to be some interference.
Not to mention the possibility of the horn being resonant and setting
up self oscillations of its own in the presence of the RF. :)

Regards
Gary