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Using a FM Dipole to transmit on 2M?

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FireBall517

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Feb 25, 2009
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OK, basically I want to use a RadioShack FM Dipole antenna to transmit on. I have a Motorola HT1000(Not the best for Ham radio, i know) and wanted to buy the adapters listed below, hook up the radio using the female sma to female bnc, I have a Male bnc to f pin female adapter, and the f pin male to fm antenna adapter. Basically can I use this to transmit 1 to 4 watts with my HT and another question, are dipole antennas directional in any way. Thanks so much.
 

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majoco

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Basically - No! You'll get a poor match from the 300ohm dipole into your 50ohm radio. The balun won't hack the power. Yes the dipole is directional. The antenna is tuned for the wrong frequency. Better get a pair of rabbits ears and extend each element 19inches each way. Or make a ground plane. See the Wiki.
 

W2NJS

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The FM antenna is "cut" for 98 mHz, which is 46 mHz below the bottom of the 2M band. It's not worth the bother to even attempt it.
 

Fast1eddie

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This is cheap and even cheaper if you have the hardware. Get a SO-239, 4 screws with washers and nuts. Finally, you'll need a coat hangar (or brazing rods as they are pretty much the exact length).

Forget the formula but I think is is 234/freq....double check me on this.....come up with 5 elements. Four will be your ground plane and one for the vertical. Scrape the ends of both the rods and mounting area of the SO239. Make a small loop on each rod and mount. Solder the vertical element and also the groundplane elements. Bend the radials to about 45 degrees, you now have a more than adequate antenna for 2 meters with excellent reception up to 160ish Mhz. Feed it with good quality coax and there ya go. Just recheck my formula, have been away from RF for many years.

It's something to get you started.

Good Signals,

Ed
 

k9rzz

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Dec 12, 2005
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No reason you couldn't try it as an experiment, but cut the antenna down to the right length. I'll leave the math up to you. :^)
 
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