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Discussion Starter · #1 ·
It's been a while sence I have been online here. Truck driveing has taken over my fishing. But with all my boat problems I have had this season It wasn't so bad. I'll get'm next time.
I have how ever a question to post to anyone that can give me guidance. I have a Cobra Marine radio (the MR F55) new with a Cobra antinna. I installed the radio as per guidance in the book and have a mount for the boat. I can recive the weather and coastguard very good but I cannot transmit. I have sent the radio back to Cobra and thay replaced the mic on it but it steal will not work. When I press the button to talk the LED screen high lites all functions on it like it has low power. I have the radio hooked to my fuesbox in the dash. Do I need to direct wire it to the battery or what. I want this for more safty than talk but would like to communicate with others on the water also. any help would be usefull.
Thanks and I will be checking back soon.
Lyman
 

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Off the top of my head, it seems like two of the most likely possibilities are inadequate DC power and a poorly-matched antenna system.

You want a fuse in the power line somewhere -- a lot of folks recommend fusing the hot and the ground both. But it probably would be wise to make sure that the fuse and the wiring are both in good shape and rated for a sufficient supply of amps. Another thing you can do is to hook up a voltmeter and check the DC supply under load -- it might show you 12 or 13 volts at rest, but when you turn on the running lights and key the radio, it might drop to 9 or 10 -- this would indicate that the battery (or the alternator or whatever) is not supplying an adequate supply of amps.

What's been more common in my moderate experience has been a poorly-matched antenna system. I know you said they were matched when they came out of the box, but I'm talking about the impedance match. When you bought the antenna, did you have to supply the co-ax cable, or at least did you put a connector on one end? (In my experience, they're usually open-ended since the manufacturer doesn't know how long you're going to need.) The times I've had impedance problems, it's most often been because I did a poor job attaching the co-ax connector. Second-most common cause has been because of a pinch in the co-ax line.

If you can take your boat by a CB shop, they can probably check the antenna system for ya. There are meters (we call 'em "antenna analyzers" in the ham community) that can sweep a spectrum of RF frequency and show you the impedance of the antenna across that band... You'll need to cover the marine band instead of the CB band, so it might be worth a phone call to make sure their meters can handle the right frequencies.

Until you get this figured out, I would strongly recommend that you key the mic only briefly. I misinterpreted the clues of bad impedance on the antenna on my car, until it fried two radios. Now my 50-w mobile transciever only does 6 to 8 watts. :(

Good luck - lefty
 

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Discussion Starter · #3 ·
Thanks lefty you've given me alot of good info. things I should have known but lost in time. I'll do some rechecking and I have a radio shop that does ham radio repair. I will check with them on the antinna. Thanks loads for the help.
Lyman
 

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Same Radio / Same problems

I have the same radio and the same problems! I sent the radio back to Cobra and they sent it back and told me to check the Standing Wave Ratio, because there is nothing wrong with the radio. I can not find anyone that thinks this is the problem, or has a SWR meter for a Marine radio. I had the antenna checked, and it was beleived to be bad. I got a new one, and THE SAME THING! I am going to take it up to the radio shop this week and let him check out everything. I will let you know if I have a power problem or what, because mine does the same as you discribed.

Dan
 

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I bet its in the length or size of your coax cable. I had a CB do nearly the same thing. My cable was too short. It seems a radio wave is 18 ft long or maybe thats a quarter of a wave and you need that much cable to get and send good signal. Turned out part of my problem was someone had used TV coax instead of radio coax in my van. LOL

The guy at the radio shop just stood there shaking his head.
 

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Oh yeah, TV co-ax cable is NOT the same stuff, ya don't wanna do that. (That's why the connectors are different.) The length of the cable does sometimes have an effect -- I did have one situation with the radio in my car, don't remember the symptom, but it did get better when I added about 18" of coax...

The MFJ 249 & 259 antenna analyzers cover 1.7 MHz to 170 MHz - the marine band is in the 150's, so they ought to be able to check out your antenna easily enough. If you can't find a radio shop, you might try google-hunting for a ham radio club in your area. Someone might be willing to meet up and check your installation for ya.

Fishfrye, the DC problem is easy to check with a DC voltmeter. Put the voltmeter across the battery -- it ought to show you in excess of 12 volts (cars are usually 13.8, we just call 'em 12 volts). Turn on the set of gear in your boat that you'll normally have turned on, and then key your radio briefly (say, for 2 seconds or so). The voltage ought to dip -- watch to see how much. If that minimum voltage is below the operating specs for your radio (check the book), then your battery is not up to snuff.

You don't want to key the radio more than you have to if you've got a standing-wave-ratio problem. I've got a couple of paperweights from learning that lesson. Now that I think about it, if you can find a well-equipped ham, he might have a "dummy load" that he'd be willing to bring over with his antenna analyzer. The dummy load is a high-power 50-ohm resistor -- basically a SWR-calibration device, a fake antenna. If the radio misbehaves transmitting into a dummy load, then the problem is not on the antenna. Speaking of which, any radio shop ought to have a dummy load as well. That might be why they're telling you it's not the radio.

Which part of the state are you in, fishfrye? I don't know a whole lot of folks, but might be able to find a club....

Lefty
 

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Send the radio and antenna back and get your money back. Get yourself a Standard Horizon radio with a Digital brand antenna.

Standard Horizon and ICOM are the recognized industry leaders in VHF radios. Matched up with a Digital antenna, you will have a great communications tool.
 

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I've never been impressed with the Cobra's. Unfortunately they simply dont hold up, but they have a nice price.

If you dont want anything fancy and will be dependable, check out Uniden Solaris, they're a good radio at a price point comparable to the Cobra and will hold up alot longer than the Cobra.

And to piggy back on Hotspot's comment... You simply cannot go wrong with Icom or Standard Horizon. I personally have the Icom and put alot of faith in it and it's always done it's job no matter the conditions.
 

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Well, I think I have my radio problem fixed? I realized something, people like me go straight for the lack of power, smart people say "check the ground". Guess what my problem was!

Lefty, I am from over around Garner just south of Raleigh. We (my wife) shows AKC labradors and we have a show at the Cabarrus event center this weekend, Friday, Saturday and Sunday. Later
 

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Lefty, I am from over around Garner just south of Raleigh.
Well then, I think I can find some local folks, if the ground problem doesn't clear things up.

Looks like the triangle-area chapter of NCAngler.com is shaping up pretty nicely...
 

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Why do you have to poke me like that, Dave? :D

I always get the short end of the stick around here.... ;)
 

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:eek: OH NO!!
 
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