Also his swr is high because of the location too. i have mine in the same spot and the farther away from the toolbox area , the lower the swr is.

 

i just hard wired mine into the back of my power source outlet in the dash........ it works fine with a cd playing but when the radio is on it cuts it out when i depress the mic but thats kinda sweet for me cause you dont have to turn it down........ but ive had mine in since i bought the truck in Aug and havent had any problems

 

there is a pic of mine..Flat SWR..once calibrated and then checked the needle dont move. I did cut the bed liner away just enough to mount the mount against the bed.

 

The "12 feet of coax" thing is false. If your antenna is tuned properly, no coax would be optimal.

All coax has attenuation. RG-58 has more than RG-8. The coax attentuates in both directions, not only attenuating your transmit power to the antenna, but also attenuating the reflected power if your SWR is off. This is why if you have over 12 feet of coax it looks like you have a better SWR. It isn't working any better, it's just giving you a better (but false) SWR.

 

Ouch! Too much capacitance there. You adjusted the antenna for a low SWR but the interaction with the cab is making it less efficient.

Low SWR is NOT the whole story.

Bob

 

So you shouldnt install an CB antenna behind the cab?
Where would be the best place to install the antenna?
Thanks ~Gage~

 

The BEST place for ANY antenna (CB, Ham, Sat, etc...) is in the middle of the roof. I know it's not practical for most. And the best mount is a permanent NMO mount. Requires a 3/4" hole. Again, NOT practical for most. I admit I was nervous about drilling (using a hole saw) into the roof. But I used ONLY quality equipment from Larsen. Larsen makes commercial grade antennas and I think they DO have a model or two TUNABLE for the CB band.

Check this site... www.k0bg.com for mobile install info. I know it's geared more towards Ham radio but CB would follow some (if not all) of the HF requirements.

I also took power DIRECTLY from the battery (using 10gauge zip cord). Both + and - are wired to the radio. Less chance of noise. I fused both + and - near the battery (cheap insurance). The radio is also fused. I used what they call POWEROLES to connect power. Used the 45 amp version.

www.powerwerx.com for a lot of products for mobile/home use.
http://www.larsen-antennas.com/mobile.shtml for antenna info.

Glad to help. I know mobile installs can be a PITA. LOL

BTW - This is one ham that doesn't mind AT ALL about helping CBers.

Bob

 

Greetings folks, been a lurker here for a couple years, but never post. I've been a licensed ham radio operator and certified skywarn spotter for 8 years, and have a reasonable knowledge and understanding of radio fundamentals. Anyway, seeing a lot of mis-information in this thread that I cant let go.

1. On the mirrors or behind the cab are the worst place for an antenna. Everyone wants to look cool, but cries when their performance is in the crapper. You signal is bouncing off the cab, and you're seeing poor performance as a result. You can tune that bugger all you want, but you will never see as good as something mounted in the middle of the roof. The poor ground plane provided by mounting behind the cab (90* good ground plane, 90* obstructed by the cab, and 180* of virtually nothing. Best performance you would see of an antenna mounted behind the cab would be off the opposite rear corner of the bed, and we all know the person you're trying to talk to is going to be in that direction. As for the mirror mounts, man, its amazing some work at all. Best place for an antenna is in the middle of the roof, through the metal. Mag mounts work, but no where near as well as an NMO, through the roof mount. Every antenna I install and use is on an NMO mount drilled through the roof, and I see far better performance than anything ever mounted to a pickup box or mirror.
2. Co-phased CB anteannas need to be 102" apart to add any value. Under this, they're actually reducing performance. Sure, they look cool, but they're not doing you any favors. Semis can get away with this, only because they're able to get them this far apart. Tell me how many sqad cars or ham rigs you've seen with co-phased antennas... None, because they're worthless and dont increase performance.
3. Power needs to come directly from the battery. Any other source, and you're likely going to experiece interferance issues. Some radios will still pick up electrical noise, in which case, an inline filter can be installed. Ground wires should go directly to the frame or metal body of the vehice. Lighter sockets are a bad idea...
4. If your SWR meter is reading 25-30, I assume your referring to the 2.5-3.0 swr which is extremely high. I'll bet your radio gets blistering hot with all that reflected power. Stop using it before you fry it! Transmit power? Not likely. Most SWR meters dont show power output, unless they're on the top end of the price scale. My SWR/Transmit power meter set me back $120, I can only assume you didn't spend that much on a meter. And if it realy was that powerful, keep an eye out for the FCC, the limit by law is 4 watts on CB. If your radio is kicking out 25-30 watts on CB, it's been havily modified and is illegal. Chances are, you radio was not designed for this kind of power and will live an extremely short life if indeed it's actually putting out that much power. As said above, your antennas are severely mismatched if your SWR is that high, probably due to the toolbox (read: really bad ground) mounting, cab interferance, and improper use of co-phased antennas.

Storm, I'm gonna pick on you for a minute. I think your intentions are good, but I suggest you take a step back before you hurt yourself or someone else. Skywarn is a group of weather spotters serving the NWS. I sit through several days of training each spring to freshen up and maintain my certification which I take very seriously. Skywarn does not endorse chasing, matter of fact they're against it, because they do not train to chase, only to spot, observe, and report. Your recent thread about deliberately driving into a storm to "warn truckers" with your CB has me very concerned. You've placed yours and others life in danger, I know your intentions are good, but be careful out there. If you're really interested in persuing your skywarn passion, get your ham ticket, get involved with a local club affiliated with ARES, RACES, and Skywarn, and get some training. I sincerely hope you didn't just assume your skywarn chaser title without getting the proper training and certifications, as there are way too many whackers out there that do this and haven't a clue of what they're doing. These people are a great danger to themselves and the public and have a tendency to upset those that take great pride it this service. I want to assume you arent one of these types, but your actions and posts about this subject lead me to believe otherwise. Please, be careful if you choose to continue doing what youre doing.

 

Cool for expanding on that WIZARDRS.

That's one problem I have. I don't explain enough. Been hamming since 1977.
Use a FT8800 and a Larsen 2/70 (closed coil) on a permanent NMO in the middle of the CC roof. Don't need DC filtering (yet).

I think a lot of folks are fooled by low SWR's. It's NOT a true reading of how efficient an antenna is.

And NEVER run "duals" on a small vehicle.

Bob

 

I've seen pics of Hams groundstrapping the exhaust system to the frame and strapping all body parts together/to the frame. On HF and CB (actually any frequency) you want the best ground-plane possible.

 

wizardsr,

Great post and info.

Welcome to FTE lots of good people and info around here. Glad you decided to join and start posting with us. Good information is always needed.

 

While I agree that middle-of-the-roof mounting is the best, I think most people are hesitant to drill that hole. I think the next best thing would be to mount it to a headache rack, or in lieu of that, to the top of a cross bed tool box.

On my (ahem) "other" truck, I have an antenna hard-mounted to the lid of the tool box, all the way at the back, and smack dab in the middle. I can open the lid on the box, and the antenna will just clear the cab. The box itself makes a pretty good ground plane, but it's electrically hard-mounted to the truck, so that helps.

 

O.k... I'll bite, and ask the obvious question:

What's a "permanent NMO mount"?

-blaine

 

I use Larsen brand Pro equipment. This link has info on the NMO mount I used. I used the low frequency mount configuration since I will not be transmitting in the microwave region. And the mounts are cheap.

http://www.larsen-antennas.com/docfi...MOHFMounts.pdf

BTW - NMO = New MOtorola

Bob

 

It's an antenna mount that uses a 3/4 inch hole.