Multi Coupler

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kvetreno

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Hi,

Does anyone have any ideas where I might find a multicoupler for a scanner and a low power (6W) transmitter. I am looking to use the same multi-band antenna for my scanner and a convert-a-com (xtva). I want to prevent inserting too much power into the receiver of the scanner and was looking for some way to block the signal from the xtva from going directly into the scanner, while permitting receive on the scanner. Any ideas?
 
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N_Jay

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kvetreno said:
Hi,

Does anyone have any ideas where I might find a multicoupler for a scanner and a low power (6W) transmitter. I am looking to use the same multi-band antenna for my scanner and a convert-a-com (xtva). I want to prevent inserting too much power into the receiver of the scanner and was looking for some way to block the signal from the xtva from going directly into the scanner, while permitting receive on the scanner. Any ideas?
Nothing that works well will be cheap.

What band is the radio?

What bands do you scan?

It gets easier if you don't scan the band the radio is on.
 

kvetreno

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The xtva unfortunatly is vhf hi, uhf and 800, mostly vhf and uhf, it's main use is for on-scene type ops as a back up of secondary radio, i have mobiles for vhf and uhf. As far as monitoring mainly the smae bands vhf, uhf and 800 smr trunked.
 

kb2vxa

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Hi K and all,

I'm surprised that nobody came up with the simplest solution of all, a coaxial switch. Most ham radio dealers carry them for VHF/UHF work and they provide sufficient isolation (20dB typical) and power handling capability up to about 300W at 500MHz.

Be advised that your transmitter may or may not like the antenna, good idea to check the SWR at the operating frequency with an analyzer before transmitting. You don't need a perfect match but over 2:1 you may damage the power output stage, a rather expensive repair.

"...while permitting receive on the scanner."

There's the rub, you can't use both at the same time without special (and expensive) considerations. They vary slightly depending on whether your tranceiver is working simplex or through a repeater. Tuned cavities provide sufficient isolation permitting transmission and reception at the same time which is a simple configuration if it's simplex but with duplex you have a pair to consider which requires more "cans" and a more complex configuration. I don't know why I even mentioned that, one look at the price tag and you'll flip. (;->)
 
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kvetreno

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Thanks for the advice. I will look at the switch. I did not mean simultaneous receive/transmit, I just don't want to fry the scanner when I transmit. I know the simplest solution would be to just use a seperate antenna, however I am really trying to limit that. I already have a dula band sti-co glass mount and a am/fm uhf/vhf sti-co disguise and the scanner antenna is somewhat hidden, I didn't want to have to add another.
 

kb2vxa

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Hi again,

" I know the simplest solution would be to just use a seperate antenna, however I am really trying to limit that."

That's because the little birdie is telling you it's NOT the simplest solution. (;->)
 
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