RF POWER OUTPUT FAIL

[Texanblue24]

I need help asap if someone can help me! I have Cobra 29 LX LCD CB Radio which is about a year old. I started having problems with hearing people so I ran the test they all failed. So I bought and replaced ALL of the wiring and the antenna then I was able to pick up someone up to 30 miles away! The sound is great and clear but no one can hear me when I try to talk! So I ran the test again on it and it came up with this RF POWER OUTPUT FAIL ! I have no idea what to do to fix this and I can't find anything online that can explain how to fix this problem without a few saying to throw it away buy a new one! I need someones help please!! Thank you for your time and hopefully your help to fix this! Randy

[silvereagle1]

long shot here but its worth a shot. i've got a uniden 980 and I once turned down the AM Power to 1 1/2 watt. when I did this it effected the radios built in meter. I started getting rf power fail antenna fail and crazy swr readings. I turned it back up to around 2 watts and everything was fine once again. I used my antenna when I turned down the AM Power so who knows what the real power was. either way I had it low enough that it messed with the internal meter. just a thought. Have you messed with the power pot in your radio just prior to it acting up?

[1206FL]

Do you have an external watt meter? If so I would use that and not the radios built in meter or test functions. Then you can truly see if you have power out of the radio. JMHO. Hope you get it resolved.

[zygoma]

We really need a little more information before it's safe to start tossing out diagnoses for what's going on. As someone already pointed out, have you gone semi-randomly turning components inside the radio that seem to just beg for a screwdriver or hex alignment tool? Most of them need *some* calibrated piece of test equipment in order to set them correctly. There's every possibility that the internal diagnostics in the radio are correctly showing a failure of some piece of equipment external to the radio. There's also a good chance that some internal fault in the radio is correctly being displayed. And the idea that the diagnostic section has a fault (i.e., the radio is putting out the power it should into a perfect antenna system but is still displaying a fault) cannot be ruled out, either.

What kind of vehicle is this radio being installed into? Where is the antenna mounted? What antenna is it, and have you made any adjustments to its length before making sure the coax run is intact? (You can do that with an external wattmeter and a dummy load in place of an antenna.) Is the antenna mounted through a metal roof, or cobbled onto a tiny bracket screwed to the side of a Fibreglas® truck cab or camper shell?

And before you pull and toss out all your RF wiring (oops, too late on that score....) see what your radio says it does into a modest 50 ohm dummy load. If you're running into questionable quality coax and an antenna that is just new out of the box, any non-resonant antenna and/or chunk of coax with a poorly installed connector is going to inject too many variables into the equation you're trying to solve.

My suggestion would be to visit a "real" radio shop with the radio installed in the vehicle it'll be used in, so that a tech can take measurements and give you a baseline of readings, with adjustments made as necessary. And then you'll know that when something changes in the future, you'll be able to compare it to the known-working status it was at the shop.

HTH


73

[Texanblue24]

I had no problems with it working until one day I went to turn it on and I couldn't get it to pick up anyone talking! So I had looked over all of the connections and found that the coax wire that goes from the CB Radio to the antenna was messed up! The part of the coax wire that was connected onto the antenna had a lot of rust corrosion in it! So I went out and bought a whole new coax wire then took out the old coax wire and ran the new one! Then I also replaced the antenna which is a Viper 25,000 watt mobile CB Radio Antenna with a new one! Then I was able to hear people from 40 miles away but it now won't allow me to talk to anyone! So I then ran the test on my Cobra 29 LX LCD CB Radio and it then came up as RF Power Output Fail. So I started looking all over the internet to see what could be causing this to happen. I never touched the inside of the radio but Ive tried to tune it in with its dials but still couldn't get it to allow me to talk to anyone. I did have someone tell me that I should buy a new mic for it that the one that comes with it is crappy (but I hadn't done that I didn't think it could be that or I would think a whole lot of people would be having problems with the mic that it comes with)! I don't have any type of testing equipment nor do I understand much about them! I've had this one and I've owned a few types of Cobra CB Radios over the years and never had any problems until now! Thank you for your time and help that you've taken out for me!

[yota167]

If the deadkey is turned too low, I'd imagine the LX would naturally fail the softwares output test. You simply need to put it on a meter and see what it is really doing. I have an LX 29 set at a 2 .5 watt carrier for my amps and it still passes the software test. I wondered how low u could go with the DK and it still pass it's own test parimaters not that it matters really.

The mic can cause receive problems if there is a short in the plug but i don't think a bad mic would cause it to fail the output test.

[Radar-DLDN]

Do you have any specific SWR numbers or just that the radio says it failed?

From my HTC One via Tapatalk

[Savoirfaire]

Hello and welcome, Texanblue24 - Randy, to the CBRT Forum from 10 X-Ray 47 (SSB) from the Eastern Panhandle of West Virginia.

I hope to catch u in the forum and on the airwaves.

There are so many operators on this site with years and years of radio experience.

You have come to the right place for fellowship, fun and/or learning.

Do not be afraid to ask.


Savoirfaire
10 X-Ray 47

Wordwide & Qualified

Years of membership:
2 years of membership

[MDYoungblood]

Hello Texanblue24,
I moved this to the "MOBILE/BASE INSTALL HELP" topic as it's more in line to this question, if you would please write an introduction for the "Welcome to the Forum" topic, http://www.cbradiotalk.com/viewforum.php?f=89 , that is for just saying "hello".
Before doing anything drastic with your radio I would get a good external meter and a dummy load to check radio and be able to set the antennas SWR. Sounds like the SWR is way off.

3's

Greg

[yota167]

Guys, the radio the OP has has an antenna warning check as well. If his antenna warning check isn't going off but his rd output check fails on the softwares test; my assumption is SWR isn't the problem but rather output is.

Whether or not the output rf fail check was caused by a high swr is not descernable at this time although highly plausible that a reflect issue may have fries the finals but SURELY the radio would be showing An antenna warning of which the OP has said nothing about.

OP; have u eer keyed this radio without antenna attached? Or without coax connected? I got 2 29lx's and the antenna warning works good on them barefoot.

*EDIT; I just noticed u said it failed ALL the tests initially. I missed that. In that case operation with high reflect may have fried the finals, which is now causing a failed output test.