Scantenna vs Discone for long distance 800s

[tilleyhat]

Hi all, for a long distance, 25 miles or more, is a discone (any brand name) better than Scantenna for a decent and audible reception of 800s P25 trunking system?
- I am 40 miles far of the 800s P25 tour what i want to listen to. i presently use scantenna. the output audio is poor.
thanks

 

[Dubbin]

Hi all, for a long distance, 25 miles or more, is a discone (any brand name) better than Scantenna for a decent and audible reception of 800s P25 trunking system?
- I am 40 miles far of the 800s P25 tour what i want to listen to. i presently use scantenna. the output audio is poor.
thanks

No, a discone is not going to do you any good at that distance. Your only option would be a yagi and that still might not do the job for you.

 

[N1BHH]

Audio has nothing to do with the signal, unless the audio is already low.

The Scantenna will do better than the discone because it looks upwards, whereas the Scantenna is focused at the horizon, more donut shaped. Unless you live in a bowl, the Scantenna will theoretically work better at signals out to the horizon.

 

[tilleyhat]

No, a discone is not going to do you any good at that distance. Your only option would be a yagi and that still might not do the job for you.

- so, i'll "enhance" my system by only changing the coax to RG-11 (or lmr-400) as per your suggestion in the other thread?

 

[ka3jjz]

I quite agree with Dubbin; you'd be far better off with a 800 mhz beam at that distance. That depends on factors such as height above ground and any obstacles such as trees, mountains, ect. (we'd need to know where you are and what system you are trying to hear - city/state will do nicely) Feeding it with a good quality coax is a must - loss at these freqs can cause noise, weak signals, and more.

73 Mike

 

[prcguy]

You should clarify that with a Discone looks upward at the higher end of its useable range, otherwise a Discone looks at the horizon just fine at lower frequencies. I'm in LA, CA on the side of a hill and can easily hear San Diego 800 and trunking over 100mi away with a Discone. Height is more important than the antenna at 800.
prcguy

Audio has nothing to do with the signal, unless the audio is already low.

The Scantenna will do better than the discone because it looks upwards, whereas the Scantenna is focused at the horizon, more donut shaped. Unless you live in a bowl, the Scantenna will theoretically work better at signals out to the horizon.

 

[N1BHH]

Look at this: http://www.tscm.com/radiapat.pdf this will clarify it for you.

 

[Dubbin]

- so, i'll "enhance" my system by only changing the coax to RG-11 (or lmr-400) as per your suggestion in the other thread?

That is correct.

 

[tilleyhat]

- What do you think about the balun/transformer 300 to 75 ohm of the scantenna? Is there the weak point (i.e signal loss) in the design itself of this antenna?
- most of discone (if not all) is terminated with SO-239 which is better than balun/transformer.

 

[Dubbin]

- What do you think about the balun/transformer 300 to 75 ohm of the scantenna? Is there the weak point (i.e signal loss) in the design itself of this antenna?
- most of discone (if not all) is terminated with SO-239 which is better than balun/transformer.

I never gave it any thought since I never had any issues with it.

 

[Airdorn]

I bet an 800Mhz mag mount on the roof (maybe sitting atop a metal vent up there) would pick the system up very well.

 

[Dubbin]

I bet an 800Mhz mag mount on the roof (maybe sitting atop a metal vent up there) would pick the system up very well.

At 40 miles, not a chance.

 

[tilleyhat]

I bet an 800Mhz mag mount on the roof (maybe sitting atop a metal vent up there) would pick the system up very well.

- yes, i've tried. i put my mag mount maxrad8053 on my house's roof. But, the result is not better than scantenna

 

[Airdorn]

At 40 miles, not a chance.

Ack, I read too fast.. I saw the 25 miles part. Yeah, time for a yagi.

My scantenna is 25ft up outside, and it doesn't do that well in the 800Mhz range either -- surely not 25 - 40 miles away.

I use one of these Yagis and it works great. 40 miles is a piece of cake.

http://www.astronwireless.com/product_details.aspx?Id=41

 

[prcguy]

That particular site has got some bogus info and look at the orientation of thier discone example. If you look up any radiation pattern on commercial discones you will find they are low angle to the horizon from the lowest freq to about halfway through the useable range then the pattern goes down a bit then gets complicated with lots of lobes. Check out these patterns and there are many more to be found with a Google search.
http://www.benelec.com.au/pdf/02590_discone.pdf
http://www.rfcomm.harris.com/products/antennas-accessories/rf-9072.pdf
prcguy

Look at this: http://www.tscm.com/radiapat.pdf this will clarify it for you.

 

[prcguy]

If you live on a hill with good line of site, sure it will. I also pick up San Diego trunking at close to 100mi with a handheld and stock rubber antenna in my LA, CA neighborhood. Height is everything.
prcguy

At 40 miles, not a chance.

 

[tilleyhat]

Do i need to point the boom's bar of the scantenna toward the tour? Or it's realy omni-directional?

 

[SAR923]

Yes, a yagi is really omnidirectional. You would need to point it directly toward the tower you want to pick up. Given the distance you want to receive, you need to be right within a couple of degrees of the direction.

 

[tactcom42]

I built an 11 element yagi for the system in charlotte nc about 50 to 60 miles away.my discone couldnt even hear this system on a 30 ft tower.but with the yagi I could decode the control channel just fine with unitrunker.On the same tower but up about 20 ft.

GO WITH A YAGI.HOME BREW IS FUN!

 

[zz0468]

Yes, a yagi is really omnidirectional. You would need to point it directly toward the tower you want to pick up. Given the distance you want to receive, you need to be right within a couple of degrees of the direction.

A typo, perhaps? The Scantenna is omnidirectional, more or less. A yagi is not.