AM/FM AUTO ANTENNA SCANNER COUPLER or a trunk lip mount??

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noblinger

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Hi I am new to this forum and need some help. I purchased a Uniden BCT-8 and will be mounting it in my 2007 Dodge Ram. I would like a good roof mounted antenna but with the tight clearance in my garage I have to go with a trunk mount or this AM/FM converter thingy. PDC634MB, SALE - AM/FM AUTO ANTENNA SCANNER COUPLER WITH BOTH BNC AND MOTOROLA CONNECTORS - Scanner World - The Largest Dealer of Scanning Radios in the World Anyone try this before does it work ok? Can you recommend a mid/low price truck lip mount antenna? Thanks for your help.
 

smittyj77

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Go with a external antenna, I have the radio antenna converter and am currently seeking a external antenna. The radio antenna is "ok" but find it spotty on VHF good on 800mhz though.
 

fineshot1

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If I only had a nickel for each time this question has been asked it would at least
pay for my RR annual subscription.

Go with another antenna mounted on the vehicle - in your case a trunk lip mount
would probably be the first choice. The larsen or maxrad triband would be appropriate.

These couplers are LOUSY LOUSY LOUSY. They will reduce you FM radio reception
and are best a complete compramise on vhf/uhf and forget 800/900 reception unless
you are right near a site.

I know this from experience and am not shooting from the hip. Some on RR will dispute
this as I have seen the nay sayers on here but I have about 35 to 40 years of two way
radio experience in one form or another and what I am telling you here is the truth.
 

datainmotion

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noblinger

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Thanks for the great information. I thought the couplers are junk just wanted to be sure. I will go with the mount that datainmotion recomended and a Larsen 150/450/800. Thanks again this is a great site!
 

kyguy

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I've been looking for the same things and have found two places that have pretty decent prices : the antenna farm and/or kollman radio - I have not dealt with either company, so I can't vouch for either.
The ants I'm looking at is the larsen 150/400/800 and the antenex trunk lip mounts(TMB8)







BE SAFE...BE HAPPY!!!
 

W2GLD

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If I only had a nickel for each time this question has been asked it would at least
pay for my RR annual subscription.

Go with another antenna mounted on the vehicle - in your case a trunk lip mount
would probably be the first choice. The Larsen or maxrad triband would be appropriate.

These couplers are LOUSY LOUSY LOUSY. They will reduce you FM radio reception
and are best a complete compromise on vhf/UHF and forget 800/900 reception unless
you are right near a site.

I know this from experience and am not shooting from the hip. Some on RR will dispute
this as I have seen the nay sayers on here but I have about 35 to 40 years of two way
radio experience in one form or another and what I am telling you here is the truth.
Please explain in a little more detail how this diminished reception with the AM/FM bands is possible? Also, have you tried one of these in the past? What type of vehicle was this on? One would imagine that this could come into play and individual results could vary.

I have a 2004 Ford Explorer with a front-passenger side fender mounted "METAL" AM/FM antenna and these adapters seem to work just fine. I performed a side-by-side comparison between this solution and my Larsen 150/450/800 antennas and while reception on the 800 side wasn't as good as the Larsen, overall it was acceptable when compared the Larsen, minimal difference and given the 800 saturation while in the City of Philadelphia or the NJSP system, either solution is acceptable for most.

I'd like to hear a little more comments from others on this issue as well. On VHF/UHF, this solution has worked excellent and I have never had diminished results on the broadcast AM/FM side, even with my HD-Radio tuner in-line.

Comments welcome!

Thanks,

Jerry - W2GLD
 
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fineshot1

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"Please explain in a little more detail how this diminished reception with the AM/FM bands is possible? "

With this bridge hookup type device you have detuned a tuned circuit(your vehicle fm antenna).

Gerry - you live and drive around a major metro area. I live and drive around on the jersey coast in between
the Philly and NYC metro areas and listen to both areas FM stations and am on the fringe of reception to both areas and after trying this POS device both times I lost all of my fringe reception(ALL OF IT).

"Also, have you tried one of these in the past?"

Yes - on two vehicles I have had in the past. After the second time I tried this I swore never again.

"What type of vehicle was this on?"

Does it really matter? Most vehicle FM radio antenna systems are of pretty much the same
hardware - either an window dipole antenna or a fender mounted(better) vertical and they all use
the same wiring to route back to the radio. Some have a preamp inline as my present one does.

"One would imagine that this could come into play and individual results could vary."

After both of my experiences I am not convinced it would vary enough to make a big difference.
 

Skypilot007

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Please explain in a little more detail how this diminished reception with the AM/FM bands is possible? Also, have you tried one of these in the past? What type of vehicle was this on? One would imagine that this could come into play and individual results could vary.

I have a 2004 Ford Explorer with a front-passenger side fender mounted "METAL" AM/FM antenna and these adapters seem to work just fine. I performed a side-by-side comparison between this solution and my Larsen 150/450/800 antennas and while reception on the 800 side wasn't as good as the Larsen, overall it was acceptable when compared the Larsen, minimal difference and given the 800 saturation while in the City of Philadelphia or the NJSP system, either solution is acceptable for most.

I'd like to hear a little more comments from others on this issue as well. On VHF/UHF, this solution has worked excellent and I have never had diminished results on the broadcast AM/FM side, even with my HD-Radio tuner in-line.

Comments welcome!

Thanks,

Jerry - W2GLD

Well these things are nothing but a glorified antenna splitter. When you use a splitter on coax feeding a radio receiver we all know what happens right.....? Half the signal to the AM/FM receiver. It will have some sort of negative effect on AM/FM reception. Will it be noticable? Every car is different but in theroy you will only see half the signal you had before installing one of these devices.
 

W2GLD

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Interesting and I agree, I expected the same results, however I did not notice this to be the case on this vehicle. Fineshot, what vehicles have you tried this setup on? Were the additional adapters involved to mate with your vehicles antenna? Also, I have driven through Ocean, Atlantic, Cape May, Hunterdon, Middlesex, and other various counties throughout the region and did not seem to have any AM/FM reception issues; before or after this installation. Granted these are different AM/FM radio receivers and that may indeed play a roll as well. I'd like to know what vehicles you tried this on so I can research the antenna wiring diagrams and the AM/FM receivers specs to see how they compare to my Fords. In the past, I had a Chevy Trail Blazer with this same setup and it didn't workout as well. Again, different vehicle, different radio, and so-forth.

Thanks for the comments!

Regards,

Jerry - W2GLD
 

fineshot1

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Fineshot, what vehicles have you tried this setup on? Were the additional adapters involved to mate with your vehicles antenna? Also, I have driven through Ocean, Atlantic, Cape May, Hunterdon, Middlesex, and other various counties throughout the region and did not seem to have any AM/FM reception issues; before or after this installation. Granted these are different AM/FM radio receivers and that may indeed play a roll as well. I'd like to know what vehicles you tried this on so I can research the antenna wiring diagrams and the AM/FM receivers specs to see how they compare to my Fords. In the past, I had a Chevy Trail Blazer with this same setup and it didn't workout as well. Again, different vehicle, different radio, and so-forth.

Thanks for the comments!

Regards, Jerry - W2GLD
1987 2 door Chevy Cavalier and a 1994 4 door Chevy Lumina Euro both of which
had the vertical stinger antennas on the fenders.

Sorry but its too far back for me to remember details about the actual hookup cabling
but I do not recall having to use any adapters.
 

prcguy

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The auto antenna scanner adapters are supposed to be a diplexer type of device that bandpass FM broadcast band to the car radio and everything else to the scanner. AM broadcast is kind of trickey and I'm not sure how this is handled since the AM radio input is very sensitive to changes in antenna configuration. They are not supposed to be a splitter and should not incur the same loss as a simple splitter.

Bottom line is these devices should not make a noticeable difference in your AM/FM radio reception and should give usable signal to a scanner in many if not most locations. There may be some brands of adapters that are not the diplexer type and that would degrade AM/FM reception, choose a known good brand. If you live in an area where scanner reception is marginal then these may not be the answer for you.

The versions I have tried worked very well for scanning and did not disturb broadcast reception. If I weren't so lazy to crawl under the dash of my new truck it would be sporting one of these adapters.
prcguy

Well these things are nothing but a glorified antenna splitter. When you use a splitter on coax feeding a radio receiver we all know what happens right.....? Half the signal to the AM/FM receiver. It will have some sort of negative effect on AM/FM reception. Will it be noticable? Every car is different but in theroy you will only see half the signal you had before installing one of these devices.
 

W2GLD

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1987 2 door Chevy Cavalier and a 1994 4 door Chevy Lumina Euro both of which
had the vertical stinger antennas on the fenders.

Sorry but its too far back for me to remember details about the actual hookup cabling
but I do not recall having to use any adapters.

"Fineshot", thanks for the reply and I have a fairly simple answer as to why you did not have success with these. If I recall correctly, the Chevy Cavalier and Lumina's had their antennas mounted in the rear of the vehicle, on either side of the trunk. The issue for you was more related to signal loss due to the type of coaxial cable used in these installations. The cable is inexpensive, basically the cheapest they could use given the frequency spectrum they were trying to satisfy. Secondly, the cheap coaxial cable is very susceptible to engine noise, vehicle computer noise and so on. Coupled with the insertion of this device, which changed the electrical properties of the radio setup, I would have expected this to work in either of these vehicles very well.

On my vehicle, the antenna is fender mounted on the front-passenger side of the vehicle, a coax run of less than 5 ft, if that. In addition, the Ford vehicles with this type of antenna setup typically use RG-8x because of the close proximity to the engine, vehicle computer, etc. Perhaps this is why on my vehicle, this setup works quite well. As I noted earlier, my Chevy Trail Blazer from 2002, didn't work worth a dam. I have also noticed that GM, Dodge/Chrysler/Jeep vehicles have much noisier electrical systems, most likely because of their choice of grounding.
 

prcguy

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AM/FM car antennas use RG-62 or a custom high impedance cable due to the very high inpedance of the short antenna on the AM broadcast band. I question the use of RG-8X on any stock AM/FM antenna and that would seriously degrade AM recpetion. When I was about 15 and didn't know any better I replaced the RG-62 on my dads truck antenna with RG-58 and AM reception all but disappeared to my surprise. I could have tweaked the AM trimmer cap inside the stock radio if I knew it existed and that would have matched the antenna better but would never completely restore the original reception.

The additional loss for a trunk mount antenna is negligible and not susceptible to interference. The worst possible spot for a car antenna from noise pickup is the front fender or wire in the front window and the only worse place would be inside the engine compartment.
prcguy

"Fineshot", thanks for the reply and I have a fairly simple answer as to why you did not have success with these. If I recall correctly, the Chevy Cavalier and Lumina's had their antennas mounted in the rear of the vehicle, on either side of the trunk. The issue for you was more related to signal loss due to the type of coaxial cable used in these installations. The cable is inexpensive, basically the cheapest they could use given the frequency spectrum they were trying to satisfy. Secondly, the cheap coaxial cable is very susceptible to engine noise, vehicle computer noise and so on. Coupled with the insertion of this device, which changed the electrical properties of the radio setup, I would have expected this to work in either of these vehicles very well.

On my vehicle, the antenna is fender mounted on the front-passenger side of the vehicle, a coax run of less than 5 ft, if that. In addition, the Ford vehicles with this type of antenna setup typically use RG-8x because of the close proximity to the engine, vehicle computer, etc. Perhaps this is why on my vehicle, this setup works quite well. As I noted earlier, my Chevy Trail Blazer from 2002, didn't work worth a dam. I have also noticed that GM, Dodge/Chrysler/Jeep vehicles have much noisier electrical systems, most likely because of their choice of grounding.
 
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