800 MHz Yagis

[chikin]

Hi all,

I am a longtime scanner owner and listener, but this is the first time I've considered getting an external antenna for monitoring.

I am primarily interested in trunked systems in the 800 MHz band and am looking for a strongly directional antenna. From my research, a Yagi seems to be a good choice. I did a Google search for 800 MHz Yagi and found anumber of hits.

One item in particular, located at http://www.primefocus.com/products/301111.html, looks like it fits the bill. The price is right and the specs look good (+13 dBi). Plus, it looks small enough that it might be somewhat portable, though certainly not inconspicuous!

Does anyone have experience with 800 MHz Yagis for monitoring? I'd like to hear other people's successes or failures.[/url]

 

[jimsokol]

I have installed a yagi at home and have had good results with it. It is a Wilson model (don't have it handy, as I am at work). I purchased it from eBay. I might suggest you do the same, as there are alot of yagis that are made for the cellular band for those in fringe areas to use. The frequency range coverage on these will also cover the public safety bands. Many dealers sell new antennas there at prices (the "buy it now" option) lower than you could get otherwise.

Also keep in mind the connectors will likely be different than what you are used to. They will probably be type N. Adapters are available but try to keep at a minimum (signal loss). Also plan on using low-loss cable like LMR-400, as cable signal loss is more prevalent on 800 mhz.

Hope this helps.

...jim in michigan

 

[JnglMassiv]

When searching for information on Yagis, bear in mind that they are also called 'beam' antennas.

 

[N_Jay]

When searching for information on Yagis, bear in mind that they are also called 'beam' antennas.

Also you have to add a LOT of elements to get any apreciable additional gain.

And as the Yago gets longer the spacing and size of the elements gets more critical.

In most cases if you want protection from noise sources at 800 you are better off with a corner reflector antenna rather than yagi.

 

[JohnO44]

Did anyone mention a 8 element Yagi avail from "The Antenna Guy" for about $90 + shipping.
I put one up 20ft w/ 9913 coax and got 3 more bars on the S-meter on my BC296D.

 

[W4KRR]

chikin, I have used yagis for the 800 MHz band.

I had a local trunked system that I couldn't receive very well. I mounted an 800 MHz yagi in a spare room in my house. I mounted it in such a way that I could rotate it by hand to get the best reception. The ability to be able to rotate it was a big factor in the reception of this system. I found that even a slight turn away from the station caused the signal to disappear completely. And, the best reception didn't come from pointing the antenna directly in the direction of the target system. The best reception came when the antenna was pointed about 20 degrees away from the station in question. Maybe this was due to signal reflection, etc. So, you should try to rotate the antenna to fine tune it for the best reception. Switching to 9913 or LMR400 coax might make a difference, however I also used RG-6 in my setup, though it was only about 20 feet or so, so my cable losses may not have been that great.

 

[69stiles]

I've always been told you had to use 50 ohm cable on antennas. I also find that most of the 50 ohm in radio shops have been sitting around for 50 years & is brittle & not the best to work with. W4KRR you mentioned rg-6 in the last message. Is it ok to use 75 ohm tv cable for antennas? I need an 800 mhz long distance solution & have access to some nice commscope rg6 75 ohm wire. Will this work? What's the difference?

 

[kg4ojj]

69stiles,

Your scanner's antenna is set for 50 ohms, so you're shooting yourself in the foot to use 75 ohm cable for the feedline. As suggested earlier, the better the cable (the lower the loss), will make your Yagi realize real gain. The shorter the cable has to run, the less loss you'll have, etc.

Now, you can use a balun and tune the feedline and antenna to match. BUT, an SWR meter for 800 mhz is not something everyone's able to afford.

I'll ask some of my amateur radio pals. My guess is it'll work, with some engineering.

 

[Covack]

I have a Yagi from wilson, about 40' up w/RG6 all total 125' run
I get excellent reception on my BC245 trunking, like some others have
posted, I not pointed exactly at the towers and I get better reception also
I have not compared the 75 ohm cable with the 50 ohm,but with all
these great post on antennas sounds like 50 ohm is the way to go
Good Luck

 

[K5MAR]

This is a regular debate in scanner circles. The best way is to get a frequency-specific antenna and use the best coax to feed it. Obviously, hardline is the way to go, and anything else is a compromise.

Now, in the real world, where most of us are using receive-only systems and monitoring a wide range of frequencies using a broadband antenna, the coax question becomes more clouded. It's better to use a quality low-loss coax such as RG-6QS (Quad Shield) even though it's 75 ohm, than to use RG-58 or RG-8 coax which has a much higher loss figure, even though it's 50 ohm.

If you are going to monitor just the 800 MHz band and use a good 800 MHz antenna, then I'd suggest you spend the additional money and buy good 50 ohm coax. Recommended: LMR-400 from Times Microwave. Of course, 1/2" or better hardline would be even better, but it's a pain to install connectors and run!

I use RG-6QS with my multi-band antennas that feed my scanners. I use LMR-400 between my VHF and UHF omnis and yagis and my amateur radio transcievers. I personally wouldn't use RG-8 above 30 MHz, and RG-58 is only for mobile use. And when I have time I plan on upgrading all my mobile antennas with LMR-200, which is better than RG-58.

Hope this helps.
Mark S.

 

[torontofreelance]

I have played around with the Yagi's with some great results. Look on ebay there are several "cellular yagis" that are around $23.00 with almost 20db gain. at that price get two, with a coaxial switch or phase them together. Major improvement over stock. For even better results replace the stock coax with 9913 belden or cable expertss 1318 much less loss on 800.