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Am I on the right track with my DIY scanner antenna?

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Joined
Jan 19, 2010
Messages
1
Location
Bellingham, WA
#1
Hi all,

I'm a real radio newbie, and have just started messing around with a BC246T. Can you believe I already want a new antenna after a week and a half with this thing? I've been reading through many of the posts here, and learning a lot. I've also done a lot of research other places. I think I've got a good idea for a dirt cheap "field deployable" half-wave dipole. But I want to make sure I'm thinking this through right. Any advice or input that the old hands here can give me would be appreciated. But go easy on me, I'm new to this.

I read that for a scanner, a 75 ohm antenna feed would work acceptably. So I bought a BNC-to-F jack connector, and plugged in the rabbit-ears from my old TV. I did use the 300 ohm to 75 ohm transforming balun. By aligning the 2 telescoping rods in a straight line, I can make a variable-length half-wave dipole from 19 - 75.25 inches long. I converted inches to meters, and meters to mhz using f=143/L (derived from L=143/f), and I'm thinking I can tune my dipole to receive frequencies from about 74.8 mhz, to about 296.3 mhz (not withstanding the banding of the scanner). A good chunk of VHF.

With some calculations and some tuning, I have so far noticed a huge difference on the Railroad and Air bands, but in theory I think I could tune in MURS, Rail, Air, 2 meter Ham, 1.25 meter Ham, and some interesting public service stuff in the upper 150 mhz, or lower 160 mhz range.

Does this sound right to you? Am I failing to consider anything that could be harmful to me or my scanner?

Your input will be appreciated,
Crabbycrab
 
Joined
Sep 19, 2002
Messages
5,278
Location
Toronto, Ontario
#2
TV "rabbit ears" antennas do a good job of pulling in 40 to 200 MHz or so. I just run each ear at about 45 degrees from horizontal (like so: \./ ); it makes for a nice directional antenna which you can use to track down transmitter locations. As you've seen, the big ears are far more sensitive than the stock duck at VHF. Dangers? Just don't poke an eye...
 
Joined
Aug 18, 2006
Messages
913
Location
South Jersey
#3
I have an off-center fed dipole (rabbit ears) mounted on a tripod as my main listening (home) antenna.

On occasion, I have 'tuned' the antenna for a specific channel based on frequency. It is mounted vertically and gives decent reception on 800 Mhz and above.

Amp
 
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