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Direction of ST-2 antenna

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#1
Hello, I currently listen to a RS PRO-163 that is linked to a Scantenna ST-2 mounted to the side of my house. I do monitor the Mass State Police 800MHz Motorola trunking system with this setup, and many times the reception quality is quite poor and full of static. I live approx 45 miles from the two nearest towers in the system. Should my ST-2 antenna be pointed in a certain direction relative to the nearest tower? If so, should the plane of the antenna be perpendicular or in-line with the line of sight to the tower, or to a center point between the two nearest towers (they're both pretty much the same distance from me as the crow flies and same power rating). Would I be better off using a 800MHz Yagi style or 800MHz omni directional??? Any advice is greatly appreciated, I'm somewhat new to this.
 

ka3jjz

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#2
You are really pushing the limits here - at that distance, hearing an 800 mhz signal 45 miles away in basically hilly terrain (as much of Mass. is) is excellent.

A Yagi would no doubt be a big improvement, as would putting it up higher. Although right now that might not be either practical nor possible.

I would do additional research first, however, and see if there are other tower sites closer to you. The Scan New England wiki and forum is where I would start...best regards..Mike
 
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kb0nly

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#3
I think you would be better off with a higher gain 800Mhz omni. The ST-2 is a good antenna on VHF and UHF from what i have seen and heard from many owners, but it really lacks on 800.
 
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#4
How about coax?

OK, so it sounds like the best solution is to change the antenna. I'm thinking of a 800 MHz Yagi mounted a little higher up (another 10' taller should get it above my chimney line). That would require approx 100' of coax, I currently have a grounding block splitting the feed line 50' from the scanner. I understand the 800MHz band is sensitive to coax loss, so should I spend the extra $$$ for the LMR or will the difference in signal strength be negligible?
 

lowerrollin

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#5
My ST-2 is really bad @ picking up 800 signals. Just the design, as everyone else that has this antenna says the same. I am surprised that you can pick up a signal with a ST-2, 45 miles away, and I cant even pick up the control channel of a system 30 miles away. The easiest way, i have found, to pick up 800 signals, is to grab a cellular yagi antenna. There cheap and plentiful from ebay. Is there any reason the line has to be 100'? Its alot of signal loss in coax. I have heard of using RG-6 Quad shield, as a alternative to LMR. I wouldnt transmit on it tho. And get N connectors if possible, there better for higher freqs.
 
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#7
Hello, I currently listen to a RS PRO-163 that is linked to a Scantenna ST-2 mounted to the side of my house. I do monitor the Mass State Police 800MHz Motorola trunking system with this setup, and many times the reception quality is quite poor and full of static. I live approx 45 miles from the two nearest towers in the system. Should my ST-2 antenna be pointed in a certain direction relative to the nearest tower? If so, should the plane of the antenna be perpendicular or in-line with the line of sight to the tower, or to a center point between the two nearest towers (they're both pretty much the same distance from me as the crow flies and same power rating). Would I be better off using a 800MHz Yagi style or 800MHz omni directional??? Any advice is greatly appreciated, I'm somewhat new to this.
well if it were me i would use a antenna rotator. some of those antennas are so sharp that you gotta be in acouple of degrees to hear something. or better yet just get a omni antenna.
 
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#8
The ST-2 is an omni antenna, but does show a slight gain off the side. Try putting the antenna side ways to the intended site or take the radio outside and rotate the antenna and see if you can find a hotspot. My ST-2 at 40 ft. hears 800 mhz signals out to 50 miles and compares favorably with a dedicated 850 mhz Larsen omni at 35 ft. If it's possible to move the antenna or go higher then that would be your least expensive option. If that fails then a small Yagi should get the job done. Better coax would get you a few db's, but I doubt enough to make a difference.
 

Swingin

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#9
I did a county by county frequency search the other day, thanks to the RR directory, starting from the county's closest to me (rural Gig Harbor) actually i'm closer to Vaughn WA, and working outward. I found that I can reach, to the North, Snohomish Co, West to, Grays Harbor, South to, Cowlitz Co Longview, and get this, East to Spokane Co, is that even possible? That's over 380 miles away, and this is all with the ST2 antenna only! I did attach my ST3 to the top of the pole, but it's not wired. Anyway, I did order a Yagi 800MHz+ and another 10' pole, this will be a 28' pole total, with the ST2 and the Yagi soon to be attached. All in all, i'm pretty impressed with the ST2, and i'm really looking forward to the addition of the Yagi, hoping it helps with the Pierce Co trunked system. Another note, i'm picking up plenty of Ham radios and air traffic controllers also, very interesting....
 
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#10
Burnstransport

45miles is pretty fair old distance for 800Mhz comm's link, of which one part is constantly mobile (the cop car - have I understood that correctly?). Anyhow, it's well within reach.

If this is specifically the band you like to monitor, a good way to monitor the towers at least, is going to be the use of 2 Yagi's - raised as high as practical, pointed directly towards each tower and connected together through an rf switch: listen to both at the same time, or switch one or the other in/out of the circuit as you wish

But what about the mobile cop car part of the link?
If I have understood this correctly, the use of Yagi's only stands to result in the mobile cops been outside the Yagi coverage beam width for a portion of the time. That means a good quality resonant omni-directional antenna is required - something like a 5/8th's length stick which will provide a nice narrow radiation pattern towards the horizon in all directions. The omni-directional could be used alone, or with the 2 Yagi's. get the 5/8th's high enough and there's a good chance you won't need the Yagi's, but to confirm that you will probably need to undertake some "link budget" calc's.

A number of benefits stem from using something like a 5/8th's length antenna: it will give you pretty much as much passive Gain as you are likely to be able to achieve with an omni-directional antenna, and in so doing the narrow beam-width it provides is also going to reduce picked up noise proportionaly. Noise is a big issue when it comes to recieving and demodulating signals which quite often are going to be borderline.

If your setup is going to be based around the 5/8th's type antenna I would also consider investing in a band specific pass band filter and complimenting it with a narrow band preamp. To work out just how much Gain your preamp needs to provide you with carry out some "link budget" calculations.

If you'd like some ideas regards exactly what hardware/components/ antennas (brand-names/models) could be used, I'd be happy to share some ideas with you.

...... it all comes down to budget.
 

Swingin

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#11
Quick question about antenna placement, as of now I have the ST2 and a Yagi. The ST2 is at the top of the 30' pole and the Yagi is a few feet down from that, is this the best placement? Or should I reverse them?
Thanks.
 
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#12
We could debate this but in reality I suspect at the end of the day it will turn out to be a case of "6 of one, and half a dozen of the other" if you know what I mean.

You've got the Yagi mounted on a horizontal arm stretched out from the main vertical pole - roughly, whats the distance from the Yagi to the vertical pole and between the Yagi and the ST2?

Having the ST2 as high as possible has to be preferable versus getting the Yagi up as high as possible - so long as there isn't anything in the immediate line-of-sight of the Yagi and the tower to which it's pointed (and then again, even if there is the whole issue of "fresnel zone" theory comes into play).

I wouldn't worry too much. This is a receive only set-up(?) Given how you have described things I doubt it's going to make any real-world difference which antenna is above the other.
 
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Swingin

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#13
We could debate this but in reality I suspect at the end of the day it will turn out to be a case of "6 of one, and half a dozen of the other" if you know what I mean.

You've got the Yagi mounted on a horizontal arm stretched out from the main vertical pole - roughly, whats the distance from the Yagi to the vertical pole and between the Yagi and the ST2?

Having the ST2 as high as possible has to be preferable versus getting the Yagi up as high as possible - so long as there isn't anything in the immediate line-of-sight of the Yagi and the tower to which it's pointed (and then again, even if there is the whole issue of "fresnel zone" theory comes into play).

I wouldn't worry too much. This is a receive only set-up(?) Given how you have described things I doubt it's going to make any real-world difference which antenna is above the other.
The antennas are both connected to the same pole, no arm. I do have plenty of trees blocking the Yagi and am not picking up the MOT in Tacoma very well. The distance between the two is about 2 1/2' from the longest part of the ST2.

Yes, recieve only, thank you..
 

Swingin

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#14
I might add that when I had the ST2 just above my roof, it was picking up pretty well, I really dont see a big difference with it being higher.
 
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#15
Are you using a metal support pole? What yagi did you buy? You could be getting interaction with the yagi and pole. As benbenrf mentioned the best support option would be a horizontal arm off the pole. Another method would be to add a short piece of pvc pipe (1-2 ft) to the top of the pole and mount your yagi there. You want your yagi as high as possible if that's your primary interest. 2.5 feet of antenna separation is plenty at those frequencies. You're not too far from Montesano, there's a guy that's selling fiberglass and aluminum military support poles (1.5 inch) on craigslist for $1 and $3 per 4 ft. that make excellent mast. If you have lots a trees blocking your signal then you may have to go higher or work on moving the antennas around to find your best location. Are any of those trees climbable or spread out enough to use as supports?
 

Swingin

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#16
Yes, 3-10' galvanized poles, I made my own telescopic pole. I got the Yagi 700-800-900MHz 11db. I did add the PVC to the top yesterday, still not a great signal, but it is stopping on the MOT channels, just very choppy. As for climbing trees, not anymore, lol. I recently lost a finger so holding on is out of the question. My guess is that because I live in the woods I'll probably never get a good signal from Tacoma. I also don't really know where the tower would be located for aiming, so what i'm doing is, I have a pair of vice grips locked on the second pole so I can run outside and turn it bit by bit.

Thank you.
 
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#17
11 db yagi will have a very narrow beam width, so you'll have to be very specific with the direction. Maybe run your radio outside on an extension cord at the poles and tweek it that way if that's possible. You could lock your radio on the control chnl and use a pair of FRS radios. Lock down the tx button and listen with the other as you move the antenna back and forth.

Another option I've done to get antennas up in trees without climbing is to use a fishing pole or slingshot and shoot a nylon line over two trees and pull your antenna up high between the span. Helps to have a helper, but one person can do it. ST-3 is so light weight, that you could easily hoist it up high. Insulate the radiating/receive element with nylon tubing and drill a hole at the top tube to keep the antenna in a vertical plane. I see that Harbor Freight has 600 ft. of 1/4 inch poly rope for $16 right now. If you have some100 plus ft fir trees then go nuts with that rope and get one of your onmi antennas up high.......:)

It would really help to know where the tower is. RR should have the station license, so Google that. There's a FCC website that you can enter the call sign and get the location of the tower. I have that bookmarked but can't find it right off hand. If you have a hill or ridge in the way I'd give up on any more efforts.
 
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#18
Swingin

Just reading through everything again I can’t help but think that this is a boarder-line signal strength situation – 800Mhz over the sort of distances you are talking about is going to leave not much in the way of signal at the antenna. Okay, your yagi is going to recover some of that, but some (or possibly even all of it) is going to be lost in that long coax run you are having to use. Just sum the situation up for us as it stands now:

- how long is the coax run and what coax type is it?
- how high is the Yagi and how accurately towards the tower is it pointed?
- the Yagi polarisation is vertical?
- any idea about the transmit channel power on this 800Mhz system?
 

Swingin

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#19
Swingin

Just reading through everything again I can’t help but think that this is a boarder-line signal strength situation – 800Mhz over the sort of distances you are talking about is going to leave not much in the way of signal at the antenna. Okay, your yagi is going to recover some of that, but some (or possibly even all of it) is going to be lost in that long coax run you are having to use. Just sum the situation up for us as it stands now:

- how long is the coax run and what coax type is it?
- how high is the Yagi and how accurately towards the tower is it pointed?
- the Yagi polarisation is vertical?
- any idea about the transmit channel power on this 800Mhz system?
I'm using two 100' RG6U cables, attached to a signal splitter-combiner at the outside of the house in a weather proof box. With a 10' cable from the box running into the house, scanner.
The Yagi is at 30' high pointing outward, south. No clue as to where the tower is yet, will check on that.
No clue on the transmit channel power either, I'm to new to this still. There are so many factors I just don't know about yet.
As of now, I am getting a two bar signal from the MOT channel with choppy reception.

Thanks everybody, I appreciate your help..

Heres some pics. If I did it right..
 

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Swingin

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#20
11 db yagi will have a very narrow beam width, so you'll have to be very specific with the direction. Maybe run your radio outside on an extension cord at the poles and tweek it that way if that's possible. You could lock your radio on the control chnl and use a pair of FRS radios. Lock down the tx button and listen with the other as you move the antenna back and forth.

Another option I've done to get antennas up in trees without climbing is to use a fishing pole or slingshot and shoot a nylon line over two trees and pull your antenna up high between the span. Helps to have a helper, but one person can do it. ST-3 is so light weight, that you could easily hoist it up high. Insulate the radiating/receive element with nylon tubing and drill a hole at the top tube to keep the antenna in a vertical plane. I see that Harbor Freight has 600 ft. of 1/4 inch poly rope for $16 right now. If you have some100 plus ft fir trees then go nuts with that rope and get one of your onmi antennas up high.......:)

It would really help to know where the tower is. RR should have the station license, so Google that. There's a FCC website that you can enter the call sign and get the location of the tower. I have that bookmarked but can't find it right off hand. If you have a hill or ridge in the way I'd give up on any more efforts.
My scanner is pretty much semi permanently mounted, the cables anyway. I tried the two way radio, but when I locked the talk button down my scanner says, found new channel, press any button, lol. OK, just turned off the close call option, so that may help.

I actually used the fishing method when I had a few trees cut down, worked like a charm. I did away with the ST3, I only have the two cables so I figured the ST2 would be the better option. When I first put it up, it was just mounted to the top of the pole with one of the antennas from it touching the ST2, kinda like the tin foil thing we used to do way back when.. It did seem to help out a bit on the FM channels, anyway, now its gone.

I'll try and find where the tower is, but at this point my guess is that the trees will be the issue, love em, and hate em...
Thanks again..
PS, if there is anybody in my area that would like to help, I can make it worth your while..
 
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