[Scan-DC] Radio Shack Antenna Tuning and Mag Mount Antenna Recommendations

[b_thom at juno.com]

On Tue, 1 Mar 2005 16:29:56 -0500 "Andy" <atlong at comcast.net> writes:
> Hi folks,
> 
> Can anyone tell me the proper length of the antenna segments on the 
> Radio 
> Shack Mag Mount Mobile Scanner Antenna Catalog #: 20-032?   I'd like 
> to 
> optimize it for 406-512 MHz UHF and 851-868 MHz.

Does this help?

>>
http://groups.yahoo.com/group/RailScan/message/5608

From:  Riley Kinney <csx333 at y...> 
Date: Tue Nov 18, 2003 1:27 pm
Subject: Re: [RailScan] Proper antenna height for 160 mhz

For 161.10 MHz:

1/2 wave 34.86"
1/4 wave 17.43"
5/8 wave 43.57"

Calculated at http://www.qsl.net/kd4sai/antencal.html

This should not severely impact receiving other high band VHF
frequencies.
<<

(No, I did not have to Google for that. I had saved that information as a
text file.)

OK, that's for RR frequencies, and it's for a single segment antenna, but
the qsl.net website might have the formulas for adjusting the segments of
the 20-032 for your frequencies of interest. I'm sure I saved a file
about the 20-032, but I haven't found it on my hard drive yet. I think I
got it from
http://eje.railfan.net/dpdp/
or, even more likely,
http://www.alabamarailfan.com/scanner.php

Again, they'll concentrate on cutting the antenna segments for best
performance at 160 MHz, but the formulas are all you need. I'll try those
websites later tonight.

Next:

> Additionally,  anyone know where to pick up a mag mount cell phone 
> antenna 
> like the ones they used to sell at Radio Shack?  These were the ones 
> that 
> were tuned to the 850 MHz range and they worked great as a temporary 
> base or 
> mobile antenna like the setup I have now.  I can't seem to find them 
> 
> anywhere even on EBAY.
> 
> Thanks,
> 
> Andy 

If those are the ones I'm thinking of, they were discontinued by RS about
three years ago. You could pick one up for $1.97 or something like that.
I snagged three of them. They work great for the trunked ~850 MHz public
service systems in Arlington and Alexandria.

They use that odd cellphone-style TNC connector, so you'll need a
TNC-to-BNC adapter to plug them in to most scanners. (Are TNC connectors
used for WiFi now?) The catalog number for the antenna was 17-318. You
might still find one in stock. It could happen.

Best wishes.