I have a brand new Cobra 29 that was working just fine, new wire's, new antenna (wilson), hooked in a 100 watt Linear amp. tuned my swr's there all below 2 hi end and low end, I know how to do this I know this to be correct and working, but know while the amp is on or off the ANT light is coming on. The swr's are fine and all the wire is new and good so is the antenna, the question is, has any one else had this problem? is there a real problem here? or is this jus feedback off the amp?
My SWR's are staying below 2 at all times, and the light comes on even if the amp is off. It was my understanding that the light should only come on it the swr is over 3 but its not. Thanks though man, hopefully its just an error.My SWR's are staying below 2 at all times, and the light comes on even if the amp is off. It was my understanding that the light should only come on it the swr is over 3 but its not. Thanks though man, hopefully its just an error.
AnonymousMar 28, 2009
have problems with my swr cant get it below 3 and have tryed 2 different antennas coax is brand new have problems with my swr cant get it below 3 and have tryed 2 different antennas coax is brand new
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I believe it to be feedback but be aware of your Standing wave ratio because using a linear amp radiates signal to the point that it could cause that light to come on. There is a problem if the radiated signal is feeding back into the amp a a higher level that it can withstand over time.
First off, how are you testing your swr? If you are using the meter on the radio chances are that it is wrong. Try to get you hands on an external meter and test for your swr. Try to get it as close to 1 as possible. It's really not hard to do. I am getting a 1.1:2 on my Pete. If your swr checks out fine with an external meter the problem is going to be in the radio and is a easy fix. Take the cover off of the radio, find the small pot labeled vr6 and with a plastic screwdriver, turn it counterclockwise just a hair. This is a common problem with the 29s. They are sometimes turned to far. Vr6 is used to adjust the sensitivity of the ant light. And when you get a peak&tune most good shops would turn this down.
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Hi,
If I may add to the two other posts, where is the SWR warning LED lighting up, in your Cobra 29 of in your linear amp?
1. If in your Cobra 29, then it is the SWR of the input circuitry of the amp that is causing the warning led. It is also possible for the jumper coaxial cable or connectors between the Cobra and the amp to be causing this. As a reminder the coax should be rated at 50ohms (RG58 or 8), connectors should be PL-259s with reducer if using 58s. One way to check is to use a dummy load at the end of the jumper cable (using a double-female adapter) which should then give a reading of flat 1. If it were the amp's input circuitry, normally there are varicaps for that purpose inside the amp.
2. If it were the amp's SWR warning lighting up, it may be that the SWR of your Wilson antenna is registering a 2 reading if using only the Cobra (@ 5 watts) to measure but increases when the power output also increases (as the case maybe when pushing the 100 watts). Your best bet probably is to lower the 2 reading down further hopefully to 1.2 which is time consuming but not impossible. Of course SWR will vary also depending also on the frequency.
Hope this be of additional help/idea. Post back how things turned up or should you need further information.
Good luck and kind regards.
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I will answer the question. Figuring that 10 amps is continuous not peak. 10 amp multiplied by 12.5 it should be good for 125 watts. But you are on the ragged edge. I do agree you should lower dreaded key but you did not ask that question. But a swing kit will solve that. That is amusing SSB and the 80 watt cobra 29 comments.
a Cb(Citizens Band) radio usually only broadcast on frequencies 26.965 to 27.405 megahertz. It is for mostly short range use 3 to 20 miles range. It comes with legal power of 4 watts. Ranges average about 5 miles. Don't expect big results off this little low-power Am transmitter. A basic 40 channel radio, Microphone, and "Magnet Mount" antenna plus 12 volt Dc 5A power supply will suffice. Place the Magnet mount on a metal file cabinet inside your house. hook up the Radio Shack 12 volt 3-5 Amp power supply to your 40 channel radio, Say Uniden pro510xl or Cobra 19 plus mini compact about $39 for these types. A $20 Radio Shack magnet mount. Turn on radio an talk. If you live in the city near lots of friends who have one too. You can talk on a private channel like Ch#40 and talk all night. The waves get quieter at night and extend farther into the Ionesphere;conditions are favorable 8pm to 12am. You should talk loudly within 5-7 miles easy. I like friends nearby; who live within 3 miles of me. Don't expect Long Distance with these radios. Unless you buy a big 1000 Watt Rf Linear an Tower 100 ft. with big Antennas costing $10,000. But remember the FCC will knock on your door and may give you 5 years $10,000 fines for anything of Linear amps 1000Watts. Just stick with basic tune and adjust,power mics(Cobra sells best). Talk with friends about fishing,hunting,gardens,tools,cars,women etc. Have Fun!!!
Check SWR with a meter, if its 1.1 to 1.5 then its fine no matter what the light says. The light can be adjusted inside to not light up until its very high(Its adjustable with a Variable knob inside) Get a Cb shop to check it out. I'd go for LIL Wilson 500 or 1000 antennas, I hear they are superb.
Hello, My name is John, Hope I can assist you...The light that comes on when you key the mike is a RF indicator, meaning you have RF power, meaning your unit is fine for talking if it is the TX light, some lights will blink as you talk. Have your SWR checked at a CB shack, or Radio Shack, etc. Enjoy.Cobras are great radios.....Hope this was helpful........
Well,first hand ,some cobra radio,s have red some have green RX/TX lights, but are you modulating? Some green lights turn red. What is your standing Wave on the antenna,s? You need to check it and the output of the radio. To do this you need a watt or field strenth meter. Can get one at Radio Shack. Your standing Wave is ok as long as it is below a 2. That has to be done on the antenna. ..hope this helps...
i would highly suggest you take it to a cb shop to get a cb tuned and peaked. before you do that though, make sure you have a good antenna system. a good antenna will have a much greater effect on your cb than tuning and peaking. as far as output, who knows? it all depends on the skill of the person doing the tuning. be warned that any output over 4 watts is illegal and you could recieve hefty fines if caught with an illegal radio.
nearly all problems are caused by poorly tuned or untuned antennas. a good antenna system with a cheap stock radio will out perform a great tuned radio with a bad antenna system any day of the week. if you dont believe me, check the firestik antenna website's tech notes. or wilson's tech notes.
for a mobile or home base setup 100 - 250 watts is enough on all modes am / fm / ssb / cw, 1000w or 1 kw would be a overkill. what transmitters rely on is a tuned antenna and swr near 1:1 or 1:1.5, achieving a good tuned antenna will give you a clean output and good signal.
Your SWR is probably NOT fine. You need to use an external meter if you have had work done to the radio. Especially if you have had a swing mod done to the radio. When you do this, the dead key of the radio is lower then the calibration knob on the radio can adjust for. It will always come up lower then it actually is.
Your radio might have been fine before the work was done on it because it was putting out very little power. Now you are most likely putting out 50 watts or more. Big jump from 4 watts.
When your raise the power in a radio, you will notice more when the antenna is not properly tuned.
In most cases with a stock CB, even when the antenna is not even near tuned, you will get a reading less then 1.5 anyway.
the more power you put out, the more important it is to have a good match.
But an external SWR meter, and check it. be careful if the ANT light is on.
You might also want to check your coax, connections to it, and your antenna for anything wrong.
My SWR's are staying below 2 at all times, and the light comes on even if the amp is off. It was my understanding that the light should only come on it the swr is over 3 but its not. Thanks though man, hopefully its just an error.
have problems with my swr cant get it below 3 and have tryed 2 different antennas coax is brand new
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