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DX949

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I have just purchased a BCD996T scanner and would like to install my scanner antenna on my roof top,a Diamond D-130J
I also have on my roof a 2 meter 70 cm dual band antenna that will transmit 50 watts out.
The only place I can put my scanner antenna is 20 feet from my dual band antenna.
my question is,will this affect my scanner when I transmit when scanning(fry my scanner if you will)
Or am I safe to transmit and scanne at the same time without frying my scanner?
thank you.
I am a newbie
 

DX949

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mlconnell said:
That setup will not hurt a thing.
A few people told me that the 50 watts being transmitted would be pick up by my scanner antenna and find its way in my scanner, and that I should put my 2 meter 70cm antenna far away from the scanner antenna to avoid this surge,And being new at this scanning stuff and ham for that matter made me put the brakes on before going ahead with my above set up.
Now why will this 50 watts not affect my scanner?
 

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Why ?
thank you for your input hoser147
 

whls3

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Just guessing what Hoser147 is getting at is probably that if you only are listening to 800, a wide band antenna won't do as well as a frequency specific, 800 antenna. But going that route will also limit you to 800 listening.

Horizontal separation of 20 feet probably is enough, but there are other factors.The ERP of the Icom./dual band antenna needs to be calculated to be sure. If you were able to vertically separate the antennae by that same 20 feet, it would be more than enough. And putting the dual band one up 20 feet higher, your range would be noticeably better.

Your screen name suggests you are in Virginia. Is that correct?
 

DX949

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Thank you for your reply,No i am not from Virginia but would like to visit one day.
I am from Ottawa Canada the Nation's Capital.

My dual band Antenna is on the peek of my roof on a trypod wich is about 4 feet tall,
My scanner antenna would be close to the edge of the roof 20 to 25 feet away from the dual bander 3 feet lower from it.
 

DX949

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whls3 said:
Just guessing what Hoser147 is getting at is probably that if you only are listening to 800, a wide band antenna won't do as well as a frequency specific, 800 antenna. But going that route will also limit you to 800 listening.

Horizontal separation of 20 feet probably is enough, but there are other factors.The ERP of the Icom./dual band antenna needs to be calculated to be sure. If you were able to vertically separate the antennae by that same 20 feet, it would be more than enough. And putting the dual band one up 20 feet higher, your range would be noticeably better.

Your screen name suggests you are in Virginia. Is that correct?
Thank you for your reply,No i am not from Virginia but would like to visit one day.
I am from Ottawa Canada the Nation's Capital.

My dual band Antenna is on the peek of my roof on a trypod wich is about 4 feet tall,
My scanner antenna would be close to the edge of the roof 20 to 25 feet away from the dual bander 3 feet lower from it.
 

zz0468

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va3hub said:
my question is,will this affect my scanner when I transmit when scanning(fry my scanner if you will)
Or am I safe to transmit and scanne at the same time without frying my scanner?
thank you.
I am a newbie
Yes, it MIGHT affect your scanner, but it's highly unlikely to *HURT* it. It will probably do what's called 'desensing' when you transmit. Your transmitter signal gets into the receiver, overloads it, and reduces it's ability to hear. As soon as you stop transmitting, the scanner returns to normal, no harm, no foul.

So, your scanner is safe, it's not going to be hurt with 20 feet of spacing, but you will very likely notice that the scanner gets overloaded when you transmit.
 
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hoser147

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whls3 said:
Just guessing what Hoser147 is getting at is probably that if you only are listening to 800, a wide band antenna won't do as well as a frequency specific, 800 antenna. But going that route will also limit you to 800 listening.

Horizontal separation of 20 feet probably is enough, but there are other factors.The ERP of the Icom./dual band antenna needs to be calculated to be sure. If you were able to vertically separate the antennae by that same 20 feet, it would be more than enough. And putting the dual band one up 20 feet higher, your range would be noticeably better.

Your screen name suggests you are in Virginia. Is that correct?
Thanks I was catchin some lunch. Hoser
 

DX949

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zz0468 said:
Yes, it MIGHT affect your scanner, but it's highly unlikely to *HURT* it. It will probably do what's called 'desensing' when you transmit. Your transmitter signal gets into the receiver, overloads it, and reduces it's ability to hear. As soon as you stop transmitting, the scanner returns to normal, no harm, no foul.

So, your scanner is safe, it's not going to be hurt with 20 feet of spacing, but you will very likely notice that the scanner gets overloaded when you transmit.
Hummmmmmm interesting,Is there anything I can install in series in my scanner to stop
this "desensing"or overload on a transmit ?
 

zz0468

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va3hub said:
Hummmmmmm interesting,Is there anything I can install in series in my scanner to stop
this "desensing"or overload on a transmit ?
Probably nothing that wouldn't cost dearly in terms of the scanner's overall performance. The best solution is to run the 2m/70cm radio at it's lowest possible power settings. If you can get it down to a couple of watts, then the scanner may be able to coexist without getting desensed.

You COULD conceivably get band stop filters for the ham bands, and insert them in to the scanner's antenna feedline, but since they're not perfect, there would be some attenuation on everything else, particularly in adjacent commercial/public safety bands. And filters can frequently have some weird responses WAY off their design frequency where they may have excessive loss. Unless you sweep it and see for yourself, you have no real way of telling what it's doing outside it's specified range. You're better off not going that route.

If you only listen to a single band, 800 MHz, say, you could use a window filter so that the scanner ONLY sees the 800 MHz range.
 

kb9hgi

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I have a dual band in my jeep and a scanner and my ham radio does not get into my scanner and the antennas are only a couple feet apart.
 

n5usr

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I have a similar setup myself - a discone for the scanner, mounted basically in the middle of two 2M/220/440 verticals, 6M and 2M SSB halos, and an HF vertical. Only problem is desense on transmit. Unless you have a tendency to hijack frequencies and stay keyed for a *LONG* time, I doubt you'll really ever notice the desense.

As someone else mentioned, if you can get vertical separation, that's far more effective than horizontal.

And I use my discone for 800 MHz systems, it works fine. It certainly isn't going to win any DX competitions, pulling in systems from 50 miles away, but it isn't stone deaf either.
 
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