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Author Topic: Using the AM/FM antenna for 2 meters  (Read 1712 times)
K4JC
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« on: December 13, 2004, 10:21:11 PM »

Years ago I recall seeing a splitter/tuner that allowed you to use your car's AM/FM broadcast antenna for both the stereo and your 2-meter rig. I believe it was rated at about 10 or 20 watts. Does anyone recall these, who made them and where I might find one? (Yes, I know they are grossly inefficient, but...my wife recently bought a new car; she wants a 2-mtr rig in it but would rather not have another antenna on it.) Any help would be greatly appreciated, thanks!
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KB1LKR
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« Reply #1 on: December 14, 2004, 06:24:54 AM »

Alternately, what about a 2m antenna that doubled as an AM/FM? Granted neither is going to be great for 2m, and my alternative requires either an expensive stealth antenna (forget who makes these, primarily for undercover but applicable to ham too) or a bit of tricky mounting of a 1/2 wave (~9" longer) in place of the original, assuming a vertical fixed 31" fender mounted whip vs. an angled, roof mounted that one now sees on some vehicles.
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K0BG
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« Reply #2 on: December 14, 2004, 06:42:44 AM »

Your memory is good, as Antenna Specialists did indeed make a 2 meter/AM radio antenna. To my knowledge, no one has made, or is making, an AM/FM version. The reason is simple; the FM frequency is too close to 2 meters.

There are other stealth antennas out there, and Larsen makes a few, as does AS. I suspect the performance is a little on the low side. Once upon a time, AS also made a 450 antenna designed like a rear seat speaker. It even set down in the parcel shelf hole. It didn't work to well either.

Alan, KØBG
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K0BG
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« Reply #3 on: December 14, 2004, 06:43:31 AM »

Your memory is good, as Antenna Specialists did indeed make a 2 meter/AM radio antenna. To my knowledge, no one has made, or is making, an AM/FM version. The reason is simple; the FM frequency is too close to 2 meters.

There are other stealth antennas out there, and Larsen makes a few, as does AS. I suspect the performance is a little on the low side. Once upon a time, AS also made a 450 antenna designed like a rear seat speaker. It even set down in the parcel shelf hole. It didn't work to well either.

Alan, KØBG
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K5LXP
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« Reply #4 on: December 14, 2004, 09:40:00 AM »

Sti-Co is the outfit that makes the disguise antennas.  

<http://www.sti-co.com>

As far as AM-FM being too close to 2M I don't think that's really the issue.  I was looking at diplexers on a VNA and it appears it wouldn't take much of a modification of say a Comet 706's 90MHz cutoff and move it up to 110MHz or so.  There would still be plenty of isolation between the ports.  The only question then would be how well would a 2M or 2M/440 work on an AM-FM car radio.  Guess you could try it out by direct connect before buying/modifying a diplexer.  It's my suspicion you don't find these items already available not because it's not possible, but that there is little demand.  Most people leave the factory AM/FM's alone and just add a 2-way antenna.  Even law enforcement, FBI, INS, etc don't bother much with disguise antennas, there are lots of VHF and UHF cellular look-alike antennas that blend right in.  That's what my XYL has on her car and it works acceptably well.

Mark K5LXP
Albuquerque, NM
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K7IHC
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Posts: 269




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« Reply #5 on: December 20, 2004, 12:07:12 AM »

Hmmm. How about a (drilled-in) NMO mount 1/4 wave 19" whip on the trunk lid?  That style of antenna is fairly unobtrusive and performs quite well in most cases.
I pretty much gave up on *disguise* mobile antennas, as they usually performed poorly for my needs.
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K4JC
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« Reply #6 on: December 20, 2004, 09:03:12 AM »

Hi, all, and thank you for the replies I have received to this post. I did find a "replacement" type disguise antenna that would probably fill the bill; however, after much searching (internet and soul) I believe that my wife's car will end up with a (still rather inefficient) glass-mount antenna (if I even thought of getting near her new Mustang with a drill she'd drill me!.) Oh, yes, I also have to install an XM radio...at least those antennas are fairly tiny nowadays!!

Again, thanks for all the suggestions.
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