I just bought Uniden PC78LTW, also bought a 4' antenna that I mounted to the outside mirror of truck. It worked fine for a few days and now both red lights come on when i key the mic.......Is this an antenna problem or is the mic bad?
I just bought a new 4 foot antenna and mounted on the truck mirror , Im having the same problem! Both red lights come on when the mic is keyed. Whats the problem?I just bought a new 4 foot antenna and mounted on the truck mirror , Im having the same problem! Both red lights come on when the mic is keyed. Whats the problem?
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I have a uniden pc 78 ltw. Peak and tuned. My light would anntena light would flash. I run a francis 5 1/2 foot with 18 ft 3in of pro8 coax. All i had to do was trim my anntena and reset the swr. problem fixed.
there ya go
Texas Mobil 219
I bought the same radio and had the radio "tuned" at a CB Shop. After that, the antenna light came on whenever I keyed the mic. I then bought a 4' tunable antenna and pulled out the whip on the antenna about an inch. I checked the SWR on the radio meter and got below 2.0 and the antenna light does not go red anymore. I do need to go to a CB Shop and have them properly tune the antenna. I heard that the CB's SWR meter isn't that accurate.
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If the antenna is tunable, you definitely need to start out by having the swr set properly on the antenna. Also, make sure the plastic ferrel, (the small round white piece) is between the top of the antenna bracked and the antenna itself. It is there to make sure the antenna does not ground out to the vehicle. If the antenna is grounding out, it will be like no antenna at all. I have also had a few customers that have had broken coaxes straight out of the factory package on cheaper antenna setups.
I have many many 10-meter radios and modded cb's. I just purchased the PC78LTW brand new in the box with a mag mount antenna on craigslist for 80bucks. I took it out of the sealed box put my SWR meter on it, set the antenna up on my tailgate, just to check if it worked correctly....after calibrating the swr, it put out over 8 miles! Not too bad at all...its going for a cb shop peak and tune, echo, and roger-beep on saturday. Point I'm trying to make is to listen to the others who responded on here...its all about tuning, and getting the radio and antenna in sync. I bought the SWR meter for 17 bucks at my local radio shop in Bow NH. Go online and read articles about tuning and you'll figure it out. I'm just a local cb hobbiest and once you get the steps down you'll be calibrating all of your friends radios because they'll be astonished at how good yours sounds.
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If you get clear audio when close to the receiver, it would appear to be a problem in either the antenna or the receiver. Try a different antenna or relocate the antenna. If you adjusted the VSWR low it doesn't mean the power is radiating correctly. Verticals should be on roof, with roof as ground plane. Mounting on mirrors is ok, but doesn't work as well. Also, if you have sheet metal near the antenna, it acts as a ground reflector and can distort or block the waveform. You might also try it with a different receiver, in case yours has a faulty pre-amp stage. It could also be a power amplifier problem in the transmitter, where it shows 5 watts but isn't putting out that amount. You can check it with an RF watt meter.
what kind of truck? does it have a fiberglass body? If it does then you would have to go directly to the chassis to mount the antenna.If you got a different antenna , like a Wilson 2000 , you could either run it co-phased or single. you would have to get mirror mounts and coax or buy a kit that has it included . Tuning a single antenna is easy but a twin is harder to do. you have to tune each antenna individually. what you also have to do is stay clear of buildings, overhead electrical wires ( high tension ) and metal objects. Now we know this is impossible so just get the SWR down as low as you can and also make sure your doors a both closed when checking the swr.
I have a wilson 5000 mirror mount. I mount it on the drivers side mirror on the upper cross arm that goes to the mirror. It is mounted on this arm with a bracket and a so 239 connector so I can undo it if I have to ,leaving the antenna connected.I can change coax and not have to worry about undoing the antenna. Remember one thing. The antenna has to be checked for SWR.each time you move it to a different spot or to a different truck.
Bad coax cable ......grounding externally or internally with shield.
Bad/poor ground for antenna..........door to body, painted parts when mounted elsewhere.
Antenna installed incorrectly. Nylon grommet must insulate antenna from contact with mounting bracket. Coaxial connector must have contact with bracket for grounding.
then the antenna needs to be moved. antennas have to have a ground plane to get correct swr below 3... or there may be a bad ground. try moving antenna @ different angles to see if it changes swr's or even opening the door away or closer to the body will make it change. also check the insulator it should be on top. call if you need help
They make a special antenna that mounts on the the mirror mount for the big rigs. You need a big antenna, as the regular one isn't going to work very well on a big rig. Many full service truck stop stores have the big rig antennas. Try that first. You might have better luck with XM than Sirius too,
This seems to be a common problem with all digital systems (especially with TV signals), and the ONLY solution is a better antenna. I suggest you search eBay, Scanner Master, etc. for a low-end (price-wise) discone and mount it as high as you realistically can.
The BEST scanner in the world is only as good as the antenna that feeds it!
You'd be suprised how much a bad mic can affect your radio. Start by trying a friends 4-pin mic, or grab a cheapo one and try it. If its not the mic, then its time for some SWR tuning, the manual tells you how to do that. Its a very simple process to do, and once you learn the steps you'll go right through it like you've been doing it forever. If your mic is good, First I'd check my coax for any kinks or breakage. Problem is a lot of times you may have a bad coax and there isn't even a kink or bend anywhere, I've seen brand new ones that were bad. Then the ground where the antenna is mounted. Can you tell me if your using a mag mount antenna or a bracket?
The pc78 is the same chassis as the cobra 29 so any info you san find on the cobra 29 will work the same for your pc78..What kind of problem are you having?? Chia
I assume your coax is not hooked up properly or you have some kink of a short in your antenna connection ( thats if your cb is working properly ) Radio Shacks Information that suggested that the 102" whip is the perfect antenna is their opion only as I prefer to recommend a full wave antenna system to my customers, but I do assure you, the 102" whip does work well if it's properly installed. I have found the main problem in the 102" whip installation is when the center hole is cut to install the antenna, it's not cut big enough, which grounds the antenna. It's not suppose to be grounded in any fashion to the automible chassis. The ground of this antenna comes from the 3 screws mounted around the outside of the antenna mount. Check that for sure. If you can't correct the problem. write me back at this web sight of direct at [email protected]. Good Luck
Ed
NC Electronic
Mills, Wyoming
I just bought a new 4 foot antenna and mounted on the truck mirror , Im having the same problem! Both red lights come on when the mic is keyed. Whats the problem?
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