Wilson 800mhz cellular amplifier for scanner

[kb0nly]

Hmm, try a new preamp then and see what happens along with checking your aim of the antenna etc.. Sounds like you got some things to try now.

If the preamp isn't helping above 400Mhz its time for something new!

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220655524205&ssPageName=STRK:MEWAX:IT

Interesting one that i came across on ebay...

 

[TEKurtz]

Yeah, I've got some more work ahead of me...note the giant mountain in between the receiver and the transmitter on the first page of this thread. Fail!
That amp looks like quality, and priced well too for the amount of gain. thanks!

 

[kb0nly]

Yeah the mountain is gonna be a problem, but if you can maybe hear a signal reflecting off something... We have a large grain elevator in town, pointing the beams at it peaks up some stuff to the north, so ya never know.

Thats a nice amp, looks like somone took a lot of time to install it into that outdoor enclosure, and a nice job at that.

 

[TEKurtz]

Here is the analysis to the intersection right down the street where the entire system comes in clear as day. I haven't got a db reading from there but it's well over 150db. Notice the difference between the two, this one clears the last little incline in terrain, it makes all the difference. On a cloudy/overcast day the signal reflects off the low ceiling and the system comes in even better in my entire area.

 

[ve9jmc]

i would definitly replace that RG-6 with a good LMR-400 or even LDF4-50 hardline. dropping in a pre-amp now with RG-6 is just going to defeat your purpose. sounds to me like 4.5 db of line loss is definitly one thing, but not only that using 75ohm coax on a 50 ohm system isn't going to help either. all that is going to do is add extra loss to the mix. you're losing so much signal down that rg-6 it isn't funny. just think of it this way.. that for every 3 db of loss that equals out to losing half the signal or power. so i would save your money on the pre-amp and change the coax. just my opinion. Cheers

 

[zz0468]

That hill will make things difficult, but not impossible... and who knows, it might even help. There is something called "obstacle gain", where a knife edge refraction over an obstacle puts more signal at the receiver than otherwise would be if it was just free space. I doubt it's the case here, but one can hope...

Ok, a couple of questions, and a couple of comments:

You mention a parabolic. How big is it? Do you know the rated gain? Does it have a feed for the proper frequency? How much gain is the yagi you mention?

 

[zz0468]

Actually there is a lot of Wilson amps in use around here, one that i know of in a fire station, without it no signal to cellphones in building. They were all approved and installed through channels so they can't be that bad.

Approved by whom? I don't doubt it helps... they DO amplify the desired signals. If not, Wilson wouldn't be selling so many of them. But the examples I've seen have no effective shielding, making them susceptible to oscillation if the installation doesn't have enough isolation. The insidious thing there is, the cellphone user doesn't notice it, but nearby public safety systems can, in the form of reduced sensitivity.

I have one as well, talked to Verizon about getting a network extender, yeah they want $250 for it and it uses my internet to provide the service they should be. I don't think so. If they gave me the extender free as an appology for horrible service i would take it.

Those are what I recommend to people who ask me how to resolve their cellphone coverage issues. Yeah, it costs, but it integrates into the network, has network approval, and is devoid of all the potential interference problems that poorly designed and installed BDA's are subject to.

Until then the Wilson amp gets me a nearby tower that has EVDO while mobile, while at home i have no data service, but so-so voice coverage.

I guess you do what you have to do. I'm nice to people the first time I encounter their flying BDA. The second time, I go straight to the FCC. It's not fun, getting dragged out of bed at 2am because of harmful interference, so you can understand why I have a strong bias against these things.

When i mentioned the amp they of course wanted to sell me a kit for my vehicle, i asked and they wanted $400+ for it. I said no i will get my own, the gal just said ok i hope it works out for you is there anything else i can help you with. They didnt seem to concerned.

No, the customer service people just want to sell stuff, which is quite ok. That's their job, after all.

 

[kb0nly]

If they are so against cellular amps then perhaps they need to provide the service they claim in the first place. My zip code is supposed to be 100% digital coverage. Yeah right... All i have to do is drive ten miles from the tower and my phone says no service randomly. Two nearby towns have no service at all, i would prefer to have an amp at hand, if nothing else for emergencies when there is no coverage without it!

I have a cell tower within a mile of my house, you would think that coverage wouldn't be a problem, Verizon owns the tower, and yet we struggle. As i said so-so voice coverage, but data is nearly nonexistent. Usually takes 4-5 tries to send a text message, keeps saying network not responding. The tower went down Thanksgiving morning, of course a tech wouldnt come out, had to go out to my vehicle and flip the amp on and use that to call their tech support on another tower, took a couple days but they did get it fixed. Without the amp i wouldn't have had any phone service in the case of an emergency.

The network extender would be nice, but i can't afford it. The wilson amp i have was bought new off ebay for a lot less than new price, i won't even mention how cheap cause you won't believe it, but it was brand new in the box and hasn't given me any problems. Perhaps you haven't used one in a while because they aren't allowed to oscillate now, they shut down and the led's go red if you don't have enough antenna seperation. Also if your near a tower and the signal is strong enough the led will go yellow meaning its shut down due to high signal strength. This one only works when it needs to. But you seem to hate them so there is no telling you that.

Anyway, enough hijacking the OP...

 

[zz0468]

If they are so against cellular amps then perhaps they need to provide the service they claim in the first place.

I suspect they would if people were not so inclined to fight cell site construction in their neighborhoods. But they want it both ways... No nearby cell site, but they insist upon the coverage.

My zip code is supposed to be 100% digital coverage. Yeah right... All i have to do is drive ten miles from the tower and my phone says no service randomly.

Damn those pesky laws of physics!

The network extender would be nice, but i can't afford it. The wilson amp i have was bought new off ebay for a lot less than new price, i won't even mention how cheap cause you won't believe it, but it was brand new in the box and hasn't given me any problems.

Oh, I know how cheaply they can be purchased.

Perhaps you haven't used one in a while because they aren't allowed to oscillate now, they shut down and the led's go red if you don't have enough antenna seperation.

Perhaps you don't know the whole story. I know of one current production model where the overload light comes on, but DOES NOT ROLL THE POWER BACK. I've seen this with my own eyes and test equipment.

A

Also if your near a tower and the signal is strong enough the led will go yellow meaning its shut down due to high signal strength. This one only works when it needs to. But you seem to hate them so there is no telling you that.

I hate them because they're almost completely unshielded, they're sold under the guise of being legal when the reality is, they're not, in the typical consumer application, the power fold-back circuitry is unreliable, they waste a lot of my time when I have to go hunt the damned things down, and I am aware of several instances of severe interference where officer and public safety was compromised directly as a result of the installation of consumer grade cellular BDA's. I can't stress that enough, although I do understand and sympathize with your point of view, people need to be aware of the caveats with these things.

Anyway, enough hijacking the OP...

Indeed. The subject deserves it's own thread. back on topic...

 

[TEKurtz]

i would definitly replace that RG-6 with a good LMR-400 or even LDF4-50 hardline. dropping in a pre-amp now with RG-6 is just going to defeat your purpose. sounds to me like 4.5 db of line loss is definitly one thing, but not only that using 75ohm coax on a 50 ohm system isn't going to help either. all that is going to do is add extra loss to the mix. you're losing so much signal down that rg-6 it isn't funny. just think of it this way.. that for every 3 db of loss that equals out to losing half the signal or power. so i would save your money on the pre-amp and change the coax. just my opinion. Cheers

Thanks for your thoughts, I appreciate it. Do you think a 6" jumper of RG6 between the antenna and radio is going to render a lesser signal then the same length lmr400? The reason I ask is I have almost the same signal issues (some freq in the band plan are clear while others are mostly static) when I test the radio right at the antenna as I do when the signal travles through the full 75 feet.

 

[kb0nly]

I suspect they would if people were not so inclined to fight cell site construction in their neighborhoods. But they want it both ways... No nearby cell site, but they insist upon the coverage.

Not here, wide open and we have been BEGGING for service for about five years now. Got a little better when they bought the Alltel towers but still not that great.

The one i have is a diecast aluminum enclosure, cant get more shielded than that, a sealed metal box with a seal on the seams. I will put some test gear on it, put the antennas near each other, and see if it shuts down, i'm betting it does because testing while the tower was down showed that moving the antennas too close to each other i had no service the second the led went red.

 

[kb0nly]

Thanks for your thoughts, I appreciate it. Do you think a 6" jumper of RG6 between the antenna and radio is going to render a lesser signal then the same length lmr400? The reason I ask is I have almost the same signal issues (some freq in the band plan are clear while others are mostly static) when I test the radio right at the antenna as I do when the signal travles through the full 75 feet.

Odd... Shouldn't be worse at that length!!

And its only a slight mismatch between the 50 ohm antenna and 75 ohm coax, not enough to worry about on a receive only setup.

Do you have any other signals nearby that are very strong?? As in so strong that its swamping the scanners receiver?

 

[ve9jmc]

Thanks for your thoughts, I appreciate it. Do you think a 6" jumper of RG6 between the antenna and radio is going to render a lesser signal then the same length lmr400? The reason I ask is I have almost the same signal issues (some freq in the band plan are clear while others are mostly static) when I test the radio right at the antenna as I do when the signal travles through the full 75 feet.

ok my misunderstanding. my understanding was your entire run of coax was RG-6. my advice would be if you are having issues directly at the antenna with the signal strength (in other words bypassing the Coax all
together) then i would reposition the Antenna. Even just an inch will make a big difference at 800Mhz. for example for me to recieve my local 800Mhz Trunk system i have my antenna in 1 certain spot. However if i move my antenna even 1 inch i lose all signal from that system (and i'm less than 2.5 miles from the Tower). so i find that recieving any signals at that frequency highly positional. i would maybe just try raising or lowering your recieving antenna a couple of inches or so and maybe moving it left or right by a few inches if possible. those would be my sugesstions

 

[TEKurtz]

No no, you were correct, my entire run IS coax. I see where I mistyped, what I was TRYING to say is when I use a 6" coax jumper from the antenna instead of a 75' jumper the signal quality is hardly different, only slightly better using the 6" jumper. I still have the same issues at either 6" or 75'.
I have come to realize how touchy the direction of the antenna is, especially at such a low db. I've spent weeks finding the best location on my property/house for the location and direction of the antenna. I know that other than installing a gigantic mast or tower I have the best reception possible where it is now. Unfortunately it's just out of reach of a few of the freq in the 16 freq band plan.

 

[ve9jmc]

What is the yagi rated for gain?

With 75ft of RG6 at 800Mhz your loosing 4-6db depending on the quality of the coax, which is significant. I'm assuming your amp is at the scanner?

I would try one of two things...

1. New feedline, LMR400 or better, 1/2" hardline, you name it. More is better at that run length.

2. Mast mount preamp instead of an inside amp. Would be far more effective to amplify the available signal before the feedline loss.

If you have 20db of gain now and want another 20db, your only going to amplify the noise as there isn't enough signal to begin with, trust me on this been there many times. Not to mention your going to have a hard time finding a preamp that will give you 40db of overall gain without a big increase in noise.

I understand your frustration.. But for the cost of a better amp you could put up better coax and even move to a mast mount wideband preamp instead. There is many available on the market.

not to say you're wrong or right but i have a few fugures i thought i would throw in there just for reference sake.

100' of RG-6 at 850Mhz has a loss of 8.534 db so for 75' his loss is 6.4 db making the Coax only 22% efficient for his application.

as for LMR-400 which would be a better chioce his losses would be 2.8 db of loss at 850Mhz making that coax 52% efficient for his purpose

for LDF4-50 hardline his loss would only be 1.528 Db making it and even better choice. but a reasonable compromise would definitly be LMR-400. but i still think he'd be losing too much signal in 75' of RG-6

 

[ve9jmc]

No no, you were correct, my entire run IS coax. I must not have explained well enough, what I was saying is when I use a 6" coax jumper from the antenna instead of a 75' jumper the signal quality is hardly different. I still have the same issues at either 6" or 75'.
I have come to realize how touchy the direction of the antenna is, especially at such a low db. I've spent weeks finding the best location on my property/house for the location and direction of the antenna. I know that other than installing a gigantic mast or tower I have the best reception possible where it is now. Unfortunately it's just out of reach of a few of the freq in the 16 freq band plan.

have you tried an onmi-directional antenna to try and catch some of the reflections that may be coming off the hills. maybe you can get just a tad better signal from that.

 

[kb0nly]

have you tried an onmi-directional antenna to try and catch some of the reflections that may be coming off the hills. maybe you can get just a tad better signal from that.

Yes i agree on the feedline, more is better as always!! I'm planning a new 800Mhz antenna and feedline here, 1/2" Heliax and a 5dB gain Maxrad fiberglass base antenna.

There is some cheap options out there, for about $100 you can get a 6dB gain Laird brand vertical for 800. I got a used Maxrad off eBay for a lot less than new cost so thats why i am going with that.

 

[TEKurtz]

not to say you're wrong or right but i have a few fugures i thought i would throw in there just for reference sake.

100' of RG-6 at 850Mhz has a loss of 8.534 db so for 75' his loss is 6.4 db making the Coax only 22% efficient for his application.

as for LMR-400 which would be a better chioce his losses would be 2.8 db of loss at 850Mhz making that coax 52% efficient for his purpose

for LDF4-50 hardline his loss would only be 1.528 Db making it and even better choice. but a reasonable compromise would definitly be LMR-400. but i still think he'd be losing too much signal in 75' of RG-6

You're right I'm sure, It's not the best to use. Being a former broadband tech I acquired 1000's of feet of RG6U, RG11U and RG6 Messenger over the years. I need to use it somewhere, ha.
As long as I know I can get decent signal at the antenna location, with or without an amp, I will replace the feed line with something more appropriate. I don't see a point in replacing the RG6 if the signal is no good at the antenna.

have you tried an onmi-directional antenna to try and catch some of the reflections that may be coming off the hills. maybe you can get just a tad better signal from that.

I started out with a 800Mhz omni as a matter of fact, unfortunately it picks up nothing unless I'm a half mile down the road.

 

[ve9jmc]

Well looks like you might be outta luck without an increase in elevation for the antenna. because if you're getting a rotten signal at the antenna then all you're going to do is amplify that rotten signal some more.