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antenna question

Posted: Sun Nov 20, 2005 3:28 pm
by mokena208
Long story short, I am just wanting to check my reality. One of the departments that I do installs for confiscated a little Chevy Jimmy and want to put a vhf mobile in it for 'covert' ops. Hiding the mobile is no problem, plenty of space for that. The sgt that I deal with wanted to know about installing the antenna inside the truck in the back so that it would be hidden. I suggested that would probably be a bad idea due to rf and the operator near by, and instead tried to point them into the direction of a disguise antenna (ie StiCo), or at least mount it under the car.

They were not to nuts about the idea, but can someone at least tell me that what they wanted to do was a bad idea?

I have to admit, that I am somewhat new to the concept of installing a 'covert' setup.

Thanks in advance.

antenna

Posted: Sun Nov 20, 2005 3:58 pm
by KB2ZTX
ASP has a glass mount cellular look a like for both VHF and UHf. If your working repeaters or neaby they work great. Granted not my cup of tea, but would rather use that than have 45 watts keying into my small brain from behind the drivers seat.


jas

Posted: Sun Nov 20, 2005 5:09 pm
by crazyboy
I would say go for a cell look alike glass mount antenna. No one will know.

Posted: Sun Nov 20, 2005 5:40 pm
by mokena208
Thanks for the feedback. I am going to suggest a cell style antenna. I was worried about them trying to put the antenna to close to the operator.

Any one have chart or something that would list distances that it would be safe to operate at a certain wattage? EG.. 30watts would be 2 feet or something like that?

Thanks.

Antenna radiation...

Posted: Sun Nov 20, 2005 7:48 pm
by Tom in D.C.
Try http://www.ARRL.org. At one point they had all this data and how to figure it out
posted in accordance with the FCC/OSHA etc. requirements. I had to do one of
these for my condo as the antenna is a relatively short distance from the top
floor unit. If I recall the results it told me that 50 watts ERP was too hot for people
at a distance of something like 25 feet so I had to cut the power to 35 watts, but
all of this is memory and may be inaccurate, so do your own figuring.

Posted: Mon Nov 21, 2005 2:45 pm
by ESDA20
Is this for a truck that will be operating inside a major metropolitan area with close repeaters? If range to a repeater is not an issue, then I'd recommend something low-key like a Phantom or Elite antenna from antenex. They practically blend into the roof of any modern looking car; and on the roof on a truck or SUV, disappear.

Posted: Mon Nov 21, 2005 4:14 pm
by mokena208
It isn't totally rural or major metro. It is a 3 village vhf repeater that has 4 voting receivers. Fairly descent coverage. They just want to have the mobile in the car so that they can do recon/covert stuff without using the black or dark blue sedan. Plus the more "street" it looks, the better. I am going to check out the antennex stuff. They of course don't have a ton of cash but want it to work well.

Not being much of an RF man, I mainly do the lighting end of the setups, I found on tessco's website what appeared to be a 90 degree mount with the NMO hole already in it. My thought was to mount it to the under-carriage. How well would this work?

Again, thanks for all the feedback.

Posted: Mon Nov 21, 2005 4:24 pm
by tvsjr
Call Stico. Tell them what you want. Pay the requisite amount of money.

The antenna under the undercarriage will suck... you'll probably have to mount it horizontally, which means it's the wrong polarity (at a cost of 20+dB.) Glass-mounts are marginal at best. The Stico will work great.

Posted: Fri Nov 25, 2005 8:30 pm
by loband
I have done plenty of this type of installs. A 1/4 wave inside near a back window works great. In crown vics, we put the antenna on the back deck and throw a base ball cap over it...

Posted: Sat Nov 26, 2005 5:08 am
by wa2zdy
That would be one big baseball cap for VHF.

Posted: Sat Nov 26, 2005 6:44 pm
by irsa
If it's an older model, just stick a slightly shorter then normal whip on it. I would hazard a guess that most people wouldn't look twice at an old Chevy SUV with a CB antenna on it.

Posted: Sun Nov 27, 2005 11:01 am
by mokena208
Thanks for all the input. I am going to blow a call into Sti-Co on Monday. Just curious if anyone has purchased one and could advise about the performance of the unit and an aproximate cost.

Thanks!

Jimmy antenna

Posted: Mon Dec 05, 2005 5:34 pm
by JustinHale
I have actually done an install in a Jimmy with the spare tire in the rear of the passenger area... The detectives REQUIRED AND INSISTED that the vhf antenna be mounted in side the spare tire rim. This is the vertically mounted spare in the rear against the side window. The antenna was on a mag mount inside the rim and covered by the factory spare tire vinyl cover. SWR wasnt the greatest but they insisted and I obliged. This being used sparingly helps. Not a very good option, BUT, a do-able option non the less.

Posted: Sun Dec 11, 2005 8:22 am
by mokena208
I ordered and installed the STI-CO antenna. The removal of the factory antenna was a pain, but getting the new STI-CO base in was even more of a pain. But, all said and done, I was really surprised by the results. Once I got it all installed, I was in a steel garage, down in a low spot and had no problem hitting the repeater, which was a good haul away.

The radio went in well. I used a GM-300 with a Quickmount remote head. The head and mic fit very well into the center console. The radio fit well in the rear side compartments.

Thanks to all who gave advice. I think that the STI-CO will work out well. Now, just to remind them to not take it into a car wash with the antenna on!

Posted: Sun Dec 11, 2005 10:07 am
by tvsjr
Sometimes you can do things on the cheap... sometimes, it's just best to pays your money. This would be the latter. For what they are, the StiCo antennas have always impressed me.

Glad it worked out for you.

Posted: Sun Dec 11, 2005 6:56 pm
by ku4zs1
Someone might have mentioned this in one of the replies here, didnt read them all. There is a way to use the broadcast band antenna has a transmitting antenna (and still keep your broadcast band radio plugged in and running). A company made a duplexer that would do 2m and 440 on the broadcast band antenna of the car. I do not remember the details or the name of the company (though I can look it up for you), but I think you replace the stock antenna on the car with another one which still looks pretty much like a regular fm antenna, but its resonate on 2m and 440. They might also make one for commercial bands as well.

Posted: Sun Dec 11, 2005 8:46 pm
by 007
ku4zs1 wrote:Someone might have mentioned this in one of the replies here, didnt read them all. There is a way to use the broadcast band antenna has a transmitting antenna (and still keep your broadcast band radio plugged in and running). A company made a duplexer that would do 2m and 440 on the broadcast band antenna of the car. I do not remember the details or the name of the company (though I can look it up for you), but I think you replace the stock antenna on the car with another one which still looks pretty much like a regular fm antenna, but its resonate on 2m and 440. They might also make one for commercial bands as well.
See posts regarding the Sti-Co products :wink: