Tuning antenna for non-installed CB?

[Martinjmpr]

Now that I have a dedicated "DD" I want to get a little more serious with my off roader (99 4runner.) Part of that includes upgrading my comms.

[ **and before anyone says it, no I'm not getting a 2m or 440Mhz HAM. BTDT (KB0LOG), IMO CB is more useful for the kind of traveling I do. Just wanted to put that out there because I'm sure the first response some people would have is "ditch that 11 meter crap and get a decent HAM." ]

Anyway, not wanting to "hard mount" a radio in my truck (no place to put it without cutting into the dash or removing the ashtray, which I use for spare change) I decided to go with the Midland 75-822. I normally install it before I go on trips where I'll need it and then remove it once I get home.

For those not familiar, the Midland 75 is a sort of "hybrid" radio: The entire radio is self-contained in a handheld unit and it comes with a "rubber duck" antenna and two battery packs (one for regular AA batteries and one for rechargeables.) However, you can slide the battery pack off and in it's place put a mobile adapter that includes a 12v cigarette lighter plug and a connector for an exterior antenna. I've never actually used it in "handheld" mode, normally I just hook it up to a magnetic-mount antenna that goes on the roof. The radio is then contained entirely in the handset and it either hangs from my rear view mirror (on the highway) or sits in my lap (on the trail.)

Of course, connecting this way means there's no way for me to tune the antenna with an SWR meter because there's nothing to adjust. As a result the radio is OK for very short range communications but for anything over long ranges it's pretty much useless.

So, my thought now is that I'll keep the radio (I like it, it's got a built in weather radio and it works well) but I would like to "hard mount" an antenna. That way when I go somewhere, all I have to do is put the radio in, plug it into the existing antenna and go.

My question, then, is what kind of mount should I go for and is it possible to "pre-tune" the antenna so that it will stay tuned even after I take the radio out? Or do I have to think about re-tuning every time I remove the radio? It's been a while since I studied radio frequency electronics (it was 1994 when I got my HAM) so I can't remember exactly what steps you have to go through to adjust the SWR.

The other requirement is that I park my truck in the garage so I can't have a roof mount as my clearance to the garage door is less than a foot now.

Here are my thoughts:

1. Bumper mount. I have an Addicted Off Road tube bumper so I thought maybe I could have a tab welded onto the bumper for a mount there.

2. Hood edge/fender mount. Should be able to clear the garage door pretty easily. Are they difficult to install? I don't mind drilling a hole in my hood, although I'd prefer not to.

3. Glass mount. Are these any good? They seem like a fad to me. I notice you don't see very many of them around, my guess is that they'd only be as good as my current magnetic mount, i.e. not very.

4. Any other ideas?

Also, what are the procedures for tuning? I can probably find someone around here who has an SWR meter, though I might consider buying one myself if they're not too expensive.

Thanks in advance! :ylsmoke:

 

[xtatik]

You know, I'm thinkin' you should.....

"ditch that 11 meter crap and get a decent HAM." ]

Dude, seriously with a set up like that...how could I resist?:sombrero:

Here's the deal. How or where you mount the radio is irrelevant to tuning an antenna. You don't tune an antenna to the radio...You simply tune the antenna to its intended frequency (or, wavelength), its counterpoise and to a lesser extent in this case, its feedline. Providing these don't change...the antenna isn't going to care how often you connect it to the radio or how often you connect or disconnect the radio. The radio's back-end just wants to see a 50 ohm (approx.) resistance/impedance. In the case of Chicken Band, it won't even matter if you change brands or types of radio's, providing they all operate in the same general area of the 11m band where the antenna is tuned to be resonant.
As you've stated, your type of traveling only requires short-range communication. So, you could use nearly any type of commercially available mount and place it anywhere on the vehicle. Try a lip mount or have a tab tacked on somewhere. It'll be good for all that can be reasonably relied upon with 4-5 watts, meaning you'll pretty much get 4-5 miles without a problem.

 

[gary in ohio]

I would say go with a Cobra 75 -WX ST, small easy to tuck way, Cheap if it gets stolen or damaged. Now for the antenna, does any of your clubs or wheeling areas have restrictions? Some dont allow long whips that can hit people watching to close in wheeling areas.

I would go for a classic stainless steel 102" whip, 6" spring on the back bumper.
Provides the best gain, A bit directional, but all your locations will be and it can be folded over to get into the garage. Skip the fiberglass models, they get beat up way to easy.