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Old September 29th 03, 02:45 AM
Soliloquy
 
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Default Outdoor Scanner antenna and eventually a reference to SW reception

Once upon a time, there was a semi-crazy man that posts to this NG. This crazy
man had bought a Uniden 785D multiband scanner but soon discovered that the
scanner was virtually destroyed by intermod, even with the simple telescoping
antenna that came with the radio. Unfortunately this man lived very close to a
cell tower and not so far from some television transmitter antennas. Woe was
this man, being reduced to using a 1 ½ inch portable antenna for the Uniden,
lest the intermod monster drive the man even more insane. The man lived with
tolerance of his 785D, realizing that it could be much much more, but having
to content himself with the abundance of local police, fire, and paramedics.
One day, as the man was cleaning his basement, he discovered his outdoor
scanner antenna from days of yore. He thought, "for old times sake, I'll hook
this antenna to my 785D to see how bad the intermod is!" To his great
surprise, when connected in a causal manner, (the antenna standing on one of
the elements, with another element leaning against the wall), there was no
intermod, even though the temporary configuration was on the end of the
property nearest the cell tower. The man was intrigued. He next pondered "I
wonder if I can use this antenna permanently", so he moved the antenna to the
desired permanent location, but withheld the final wiring until sure. Lo and
behold, the antenna worked there as well, though a little tweaking of the
location was necessary to insure optimum performance. The permanent location
was to the rear of the house, and the first trial location was to the front.
The offending antennas would be on an axis of about 45 degrees if the front of
the house was assumed to be zero degrees and the rear of the house 180
degrees.

Bottom line, when I got the radio, I had hoped to use my outdoor antenna, but
had the intermod problems as described above. I did not believe it possible to
use the outdoor antenna, since any form of indoor antenna would produce
grotesque intermod distortion from the cell tower and television stations. ALL
of my portables are plagued by intermod in this location, though the Yaesu
VR-500 and the Alinco DJ-X10T can handle the intermod if their attenuation
features are used. My Yaesu VX-5R is hopelessly plagued by intermod in this
location.

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 and
http://www.starkelectronic.com/scanner.htm and
http://www.valcoelectronics.com/scanner/scanner.htm though I purchased it at
Radio Shack several years ago.

I thought that if the telescoping antenna caused massive intermod that there
wasn't a chance to use an outdoor antenna, where I figured that the signal
levels would be higher. With the Uniden, the reception in the upper 800 MHz
range seemed dismal with this antenna, but I connected the Alinco DJ-X10T and
viola, great signal levels. Apparently my 785D isn't very sensitive at those
frequencies.

Oh, and by the by, when I connected the Alinco DJ-X10T to the antenna, I got
surprisingly good shortwave reception, at least on the several frequencies
that I tried. The antenna is fed by coax, so I don't believe the feedline
helped with reception. Any insights into why the scanner antenna would offer
augmented reception down to as low as the 7.415 that I tried it at? It is
rated to 30MHz, I guess that might be part of it.

Using the antenna, I am now able to use the Uniden Service searches, such as
aircraft, railroad, CB, FRS, and marine with a high degree of success.

Regards.
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Old September 29th 03, 03:11 PM
Diverd4777
 
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Default

In article , (Soliloquy)
writes:

Unfortunately this man lived very close to a
cell tower and not so far from some television transmitter antennas.


Hmm...

- Maybe this man should call up MFJ Enterprises

http://www.mfjenterprises.com/index.php

& see if they have a pre selector for a Scanner . . .

- Relay the information to your freind

~Anon~
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Old September 29th 03, 04:04 PM
Warpcore
 
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Default

Perhaps this fortunate one discovered some directionality s ? Woe unto the
celluar towers ! For the wrath of wire cutters and high explosives shall
terminate their reign LOL.


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