Low Band...LOW clearance antenna ideas...neone?

afterimage84 · Post by **afterimage84** » Wed Jul 07, 2004 4:43 pm

ok...local fd has got a new truck(pierce dash cab), problem garage door clearence is...ten inches i think...maybe ten.

i was thinking ball spring on the side with a whip and bend it when parking...? best plan?

bnn121 · Post by **bnn121** » Wed Jul 07, 2004 4:52 pm

Try here

http://www.untenna.com/

some people swear by them...some people hate them. I think there great for single frequency stuff...becuase they do not tune real easy and once you get it on your main dispatch channel there tollorence on either side is not that great...for changing channels. now this is on the lowband version...it getts better in the upper bands....they sit approx 6 inches high...thats if you get the antenna and the platic dome that can cover the antenna...thats up to you....just remeber once you tune the antenna without the cover on...you will need to fine tune it a bit more with the cover on it. very time comsuming...but they do work and the do sit low to the top of the cab.

I use a wiltron site master to tune these bad boys after I mount them on fire trucks or ambulances...they need a really good ground plane to be effective.

nmfire10 · Post by **nmfire10** » Sun Jul 11, 2004 9:31 am

I just had a similar situation placed in my lap. Since our building expansion is going very slow and our new heavy rescue just arrived early, i have VERY little clearance for antennas. I'll be ok with UHF but I am going to need a low profile low band antenna. Are there any other makes besides the one above?

commtek · Post by **commtek** » Sun Jul 11, 2004 11:58 am

bnn121 wrote:Try here

http://www.untenna.com/

some people swear by them...some people hate them. I think there great for single frequency stuff...becuase they do not tune real easy and once you get it on your main dispatch channel there tollorence on either side is not that great...for changing channels. now this is on the lowband version...it getts better in the upper bands....they sit approx 6 inches high...thats if you get the antenna and the platic dome that can cover the antenna...thats up to you....just remeber once you tune the antenna without the cover on...you will need to fine tune it a bit more with the cover on it. very time comsuming...but they do work and the do sit low to the top of the cab.

I use a wiltron site master to tune these bad boys after I mount them on fire trucks or ambulances...they need a really good ground plane to be effective.

I agree with the above. We use a lot of these for clearance problems. They work well, but take a lot of time to tune. You order them on a center frequency in your list, and this takes some of the frustration out of tuning them. But you still need a site master or such to make life easier. One other note is they are NOT wide band at all.

nmfire10 · Post by **nmfire10** » Sun Jul 11, 2004 12:15 pm

How narrow is it then? We are centered on 46.06 but mutual aid would take a swing from 45.88 up to 46.72

Tom in D.C. · Post by **Tom in D.C.** » Sun Jul 11, 2004 12:28 pm

The manufacturers' spec sheets are the only reference you can trust on this. My experience with VHF units was about 500 kHz each side of center to keep the SWR under 1.5:1. They all stink on bandwidth compared to what we're all used to on conventional antennas. A/S, now a part of somebody else but I forget who it is, also used to make bus/truck antennas which were vertically polarized but ran horizontal on the vehicle roof with a plastic radome. These were NOT the circular-type antennas that the untennas are, but rather a stretched-out antenna that might, I say MIGHT, have/have had better bandwidth. I don't know if such an animal is still available, so do some searching.

bnn121 · Post by **bnn121** » Sun Jul 11, 2004 2:21 pm

Sinclair Technologies Inc makes the Excalibur series. I've installed these also..but these things are very long...so you need alot fo cab room on top...or on the box...if thats where you install it. These come pretuned to your center freq. You can adjust them some...but not really needed...as they seem to perform very well. Unless your going more than 2 or 3 megs off center.

http://www.sinctech.com/catalog/product.aspx?id=1266

commtek · Post by **commtek** » Sun Jul 11, 2004 4:45 pm

nmfire10 wrote:How narrow is it then? We are centered on 46.06 but mutual aid would take a swing from 45.88 up to 46.72

You can get that out of it without hurting the radio's PA, but the swr will be near 3:1 or so on the fringes. A lot of the ones we do are tuned for 33.76 center and will cover 33.52 to 33.98, but the swr creeps up on the ends of that.

Post by Pj » Sun Jul 11, 2004 5:49 pm

Hey Matt... I know you guys down there Madsion are the cream of the crop, but the truckers figured this out YEARS ago!

(Matt screaming at people in the 81/79 circle)

Actually, at the chief's show a couple of years ago, one department had their low band antenna mounted to the mirror due to clearance issues. They said is still worked pretty well. It was from someone in NY.

nmfire10 · Post by **nmfire10** » Sun Jul 11, 2004 7:59 pm

Thats not a bad idea but I would probably be shot, drawn & quartered, and stoned outside Circle Pizza if I put an antenna on the side mirror of this truck.

And give me some credit, I don't have grey hair yet. It'a 80 and 79. 81 and 80 is the one in K-Town.

KitN1MCC · Post by **KitN1MCC** » Wed Jul 14, 2004 2:49 pm

i know NU uses a system with a 60in whip and this maching setup that was once made by GE

KB2ZTX · Post by **KB2ZTX** » Fri Jul 23, 2004 5:51 am

We use alot of the Untenna units. I have ours tuned for 46.14 (dispatch) and we use them from 45.92 - 46.46. They do send the swr up a bit ion those areas, but the new radios also power down if that happens. The nice thing about that antenna is it mounts to an NMO. As soon as it permits we put a spectrum on it.

Jas

Mike in CT · Post by **Mike in CT** » Fri Jul 23, 2004 8:52 am

Personally I think 77 & 80 is where its all happening...

Mike
KM1R

Low Band...LOW clearance antenna ideas...neone?

Low Band...LOW clearance antenna ideas...neone?

Untennas, etc.

antenna

NoMad