Bob,
The most recent instance was with a Cushcraft ARX-270 2m/440 antenna. I
watched this antenna being assembled, and I can state that there was no
corrosion, maladjustment, or looseness involved. We used that antenna briefly
for a 2m repeater simply because it was already in place, and we had a special
event to cover. A Motorola RKR-1225 repeater was hooked to it using LDF2-50
Heliax feedline. When the Cushcraft antenna wouldn't work without major
desense, I swapped it for a Sinclair SRL-222 dipole, which worked perfectly.
73, Eric Lemmon WB6FLY
Bob Dengler wrote:
> At 5/12/2005 12:37 PM, you wrote:
> >Yes. Many repeater receivers are simply not well enough shielded to
> >keep the TX from leaking into the RX box. Even some commercial
> >repeaters will suffer desense if 100% shielded feedline is not used. I
> >have seen serious desense occur when a dual-band (2m/440) antenna is
> >used on a repeater, due to the uneven gain versus frequency response of
> >many such antennas.
>
> A narrowband antenna by itself will not generate desense. Your problem was
> probably due to corrosion, dielectric breakdown, or some other cause
> related to poor construction/materials in the amateur grade antenna.
>
> I would like to know what model antenna this was though, since I have yet
> to see any desense problems with my Comet antennas.
>
> Bob NO6B
>
>
> Yahoo! Groups Links
>
>
>
>
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