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CB Radio Forum - Discussions regarding Citizens Band Radio (CB)

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Old 09-13-2017, 12:27 PM
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Smile pre amp- from Italy

Anyone have any experience with 100 watt pre-amps made in Italy ? I am think about one for my pick up truck. Where ? can I send it and my mobile CB to get them peaked out ? Thank you guys for all your help.
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Old 09-13-2017, 12:54 PM
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Quote:
Originally Posted by arkieguide View Post
Anyone have any experience with 100 watt pre-amps made in Italy ? I am think about one for my pick up truck. Where ? can I send it and my mobile CB to get them peaked out ? Thank you guys for all your help.
Do you mean 100 watts POWER AMPS?

You should most definately NOT have your factory tuned CB radio "peaked and tweaked". Especially if you plan to add a 100 watt power amplifier. You will have a radio that splatters and sounds like crap. Don't do it.

Spend your money on a quality, well installed antenna. I suggest a Larsen NMO-27, available in Chrome or anodized black. The antenna needs to be mounted in center of the cab roof, and tuned properly. Find a decent two way radio shop to properly install the antenna and tune the VSWR. Don't bring it to them with any power amplifiers or mention the amplifier or any peaking or tweaking of the radio. If they are legitimate radio shop with licensed, competent technicians, they will show you the door.

If they tune your NMO-27 antenna with minimum VSWR centered on the middle of the band, and if later you decide to Illegally install a 100 watt amplifier from Italy between your still factory tuned CB radio and the professionally tuned Larsen NMO-27 antenna, you will sound marvelous. Just don't add a power mike or Rodger beep.





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Old 09-13-2017, 1:08 PM
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Most CB power amps are designed for a 4-watt input. If you apply the golden screwdriver to the radio you will splatter across several channels and sound like crap on every one. And you can fry your amp.

Adding an amp is probably a bad idea, overdriving it is even worse.
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Old 09-13-2017, 1:10 PM
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Thank you. Now to center antenna over cab. I have a light bar just behind the cab, about 2" above the cab. Can i attach a plate 1/4" x 24" to the light bar and mount the antenna to it, instead of putting a hole in my cab roof.?

This forum is great help, thank you and the others that are good to help people.
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Old 09-13-2017, 1:22 PM
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You can, but minimum SWR will go up, antenna performance will go down, and if the light bar is LED, the RFI from the antenna will probably fry the LED driver circuitry.

Drill the hole. Antenna performance will improve sufficiently that you probably won't need a 100-watt power amp.
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Old 09-13-2017, 1:44 PM
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I'd strongly recommend the Larsen NMO-27 mounted in the center of the cab roof. Yes, it requires a hole, but I've installed a lot of NMO mounts over the last few decades and never had one leak. In exchange, you get the best possible performance from the antenna.
As Jon said, mounting off something else will impact the ground plane. You need to look at the ground plane as the "other half" of the antenna, because it is. Doing anything to screw up that ground plane will impact performance.
There's no point buying an amplifier/golden-screwdriver'ing your radio if you don't do a proper antenna installation.

The few times I use a CB in my truck, I use the Larsen NMO-27 mounted on the cab roof. I tuned this antenna using my antenna analyzer from work. 1.3:1 swr on channels 1&40 and 1.03:1 swr on Channel 19. Very nice smooth SWR curve across the CB band. Driving from California to Texas and back showed it worked very well, received great (not many people to talk to, but that wasn't the antennas fault).

The Larsen brand has been around for decades and they make very high quality professional mobile radio antennas. While it'll cost a bit more than a consumer grade antenna, it'll easily outlast your vehicle. My NMO-27 is probably 20-25 years old, still works great.

As for amplifiers, pre-amplifiers, tweaked radios, and antennas, the #1 thing you can do to improve a radios performance is to use a properly installed and tuned antenna. Doesn't matter how much power you run or how much you spend on your radio, if the antenna isn't up to par, then it's all for naught. Start with a good antenna, and go on from there.

Beware of the "peak and tune" guys. As others have said, they can make a radio show more power output on a meter, but it usually comes at a cost. If you really do feel the need to have someone tweak your radio, make sure you find someone with the right test equipment. That means a proper RF service monitor. Not just a guy with a watt meter. Rather than trying to squeeze "more watts" out of the radio, have them focus on making sure the radio is on frequency and putting out a good clean signal. That, coupled with the good antenna will probably do what you are looking for.

Throwing RF power alone at the issue won't necessarily solve the issue.
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Old 09-13-2017, 4:51 PM
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If I might add to what Mmckenna said. If you really feel the need to have a tech adjust frequency or measure the signals on a systems monitor, have it done by a licensed tech at a land mobile radio shop, the same ones who can drill the correct sized hole for the NMO mount and tune the antenna. But, make sure the tech has certifications such as an FCC general radio operators license GROL. There are far too many "golden screwdrivers" out there.

Frankly, CB radios are very simple devices. Unless the CB radio is well over 25 years old and terribly abused, it is probably working just fine and will be very happy connected to a properly resonating NMO-27 antenna. A brand new radio will be cheaper than the extra hour of technician bench check. If it is an older SSB radio, there might be some need to adjust the oscillators that inject carrier for SSB reception, however, unless the clarifier needs to be tuned way to one side or the other, it is probably fine. Far too many radios are mangled by the "golden screwdriver" . Watch a few you tube videos about tweaking and peaking a CB radio and you will realize what hacks most of these guys are.

Did I mention the NMO-27 antenna, center mounted on the cab, tuned for minimum VSWR?

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Old 09-13-2017, 4:59 PM
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Quote:
Originally Posted by arkieguide View Post
Thank you. Now to center antenna over cab. I have a light bar just behind the cab, about 2" above the cab. Can i attach a plate 1/4" x 24" to the light bar and mount the antenna to it, instead of putting a hole in my cab roof.?

This forum is great help, thank you and the others that are good to help people.
Ditto on not doing that. You will mess up the ground plane and you will get worse terrible noise from the light bar.

The "hole" requires an exact sized hole saw. That has been discussed at length that you can easily use the wrong type with the "proper diameter" and the hole will be too large, you can drill it again, but it will still be too big. No kidding this just happened to a guy on these boards. You can read about it elsewhere at length.

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Old 09-13-2017, 5:04 PM
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Once again I thank you folks, for all your help.
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