800mhz Antenna Suggestions

[Drkatzjr45]

I live in an area of far South Tulsa where reception of our 800 system is weak and variable.

I am not looking for something large like a discone, but something that might markedly improve 800 reception.

I have tried the standard Radio Shack 800-based scanner antenna, and it doesn't seem to provide that much improvement. I have also tried those available through Scanner Master....

Anyone familiar with Max System Antenna for 800, or would anyone have -any other- suggestions?
Again, not looking for something huge in size at all, but something that will really improve reception
on my base and mobile here in S. Tulsa.

Thanks!!

 

[rfradioconsult]

There aren't any "magic" 800 MHz antennas, it sounds like you have tried several with about the same results. Perhaps your problem is you do not have a good line-of-site to the 61 & Sheridan site or the BOK site down town.

Users on the 800 MHz also have some problems in south Tulsa; however, their radios are much more robust than your scanner, even then it gets spotty for receive. The 800 system have several receiver "voting" sites around so in most area the dispatcher usually can hear the field unit, but the field unit may not hear the dispatcher.

Have you tried an outside antenna, it may help but don't expect a huge difference.

I have problems along Memorial about the Spirit Bank Center and several others, but at home is ok 76 & Sheridan.

 

[kb5udf]

Homebrew solution

I built one of these: Build A 9dB, 70cm Collinear Antenna

Optimized for 855 mhz or so. It is easy enough that even I could do it, and that's saying something, as I'm highly mechanically challenged. The link is for a 440mhz design, but just do the math and adjust the size. All you need are:

4 feet or so of coax (about any kind will do)
Two wire coat hangers.
Pvc pipe
Thin wooden dowel

I use the straight part of the coat hanger wire for the 'tip' and I use an identical piece of wire in the base instead of the aluminum pipe/collar. I mount the whole thing in ordinary pvc from home depot, after duct taping the snakelike antenna to a thin wooden dowel.

I find that this design REALLY does work, compared with a 3db magmount on a decent ground, this antenna pulled in fringe systems reliably. One other tip though, when you shove the antenna into the pvc Pipe, you'll want to have the pipe 1 foot or so longer than the antenna is, so that when you try to mount the base of the antenna to something, you would be obscuring part of the active part of the antenna. I don't believe the torroids are neccessary and omitted them w/out ill effects.

Let me know if you have any q's.

 

[iamhere300]

I got to agree with RFRADIOCONSULT's thoughts, but if you want a pretty good
antenna for 800, just use a old cell phone antenna. I have some mag mounts that I use,
and the results are impressive.

 

[n5bew1]

I use one of these antennas at about 25 ft to pull in the Chickasha DPS 800 site from east Norman. Mobile an old 800 cell phone mag mount works well also.

www.lonestarelectronicsco.com/downloads/ls800.pdf

 

[car2back]

Get a mobile 800mhz NMO and mag mount... slap that bad boy on a metal cookie sheet for ground plane.

 

[Drkatzjr45]

Yes, I agree with rfradioconsultant. I think it is a line of site problem. I feel that reception drops
b/c of the hill in the terrain between 71 and 81st and -Yale--; thus everything to the south, in this zone,
except to the East, has variable reception. Thanks for all responses and feedback!!

 

[Tulsey]

Good suggestions on using cellphone antennas. In 800, like any other band, height is power. 800 has special problems. 1. You could have the greatest antenna mounted very high and wind up with almost as bad a signal as an antenna on the back of the scanner because 800 has so much loss in the cable so good cable is very important. 2. Adapters, try to avoid them or as many as possible for 800 because they cause much more loss for 800 compared to the lower bands. .

 

[plaws]

You could have the greatest antenna mounted very high and wind up with almost as bad a signal as an antenna on the back of the scanner because 800 has so much loss in the cable so good cable is very important..

It's the cable that has attenuation at higher frequencies, not the other way around, but yeah, absolutely!

Someone posted to a thread about using 50' RG58 for listening to 800 MHz and wouldn't believe that this was a bad idea since he was only receiving. Sorry, but as you note, neither the feed line nor the RF cares which direction it's going and the signal WILL be attenuated!

See here to check how much difference good coax makes. Coax Loss Calculator