wrote in
om:

I'm glad that someone wrote in response. The purpose of the post was to
pique the interests of those that also have been plagued by intermod.

As to signal strengths and feedline loss, the signals are actually
greater now then when using the "rubber duck" antenna. I was unable to
use the "Service Searches" that are part of the Uniden 785D system. There
simply was no signals available with the indoor antenna, save for the
blasted and incessant intermod. Nothing has changed in the local cell
tower, since my Yaesu VX-5R is virtually destroyed in this location, as
are the other handhelds that I have if I use them un-attenuated. I have
still to try the experiment of using the VX-5R coupled to the outdoor
antenna to see if it is still plagued by intermod.

Brand new, RG6, Radio Shack supplied and about 85 feet. The antenna has a
300 to 75 ohm matching transformer. At first I was concerned that the RG6
should have been RG58, since the antenna is older (I came across the
Radio Shack info for another scanner antenna that they offered, and it
recommended RG-58). I notice that the newer scanner antennas (such as my
model) recommend RG6. Eventually I came across this link
http://www.barovelli.com/radio/scan/scanant.htm as well as other links,
and came to the conclusion that for scanner work, the difference between
50 ohms and 75 ohms could be ignored.

Anyway, if it wasn't for the greatly augmented "Service Search"
capabilities with the outdoor antenna, everything ranging from CB,
Aircraft, Marine, Railroad, through FRS, I would also have thought that
attenuation would have explained it. Someone suggested a bit of
directionality might account for the increased resistance to intermod,
but with the antenna involved, it would be hard to believe that was the
case.

Regards.


Soliloquy wrote:
Any insight into why the scanner antenna would permit normal
operation of the 785D without the problems of intermod being a real
nuisance? My outdoor antenna is identical to the Antenna Craft ST-2
seen (minimally) here http://www.durhamradio.com/scanacc.htm

Very strange. Obviously your scanner can't handle the strong local
signals picked up by your small "rubber duck" antenna. So obviously
the outdoor antenna is delivering LESS signal to the scanner. You may
be hearing more signals, because the scanner is no longer being
de-sensitized by strong signals.

I suspect you're getting a lot of loss in the feedline.

What type of coax are you using? What length of coax? And how old is
the coax?
If it's a long run of old weather beaten RG-58, that would explain it.

As the saying goes, "Scanners don't need pre-amps, they need
attenuators."

Art N2AH