Question about Cobra 148 GTL 120-Channels Base CB Radio

2 Answers

148 gtl receive works fine transmit has no power

Radio has had no mods. all works well on receive. With another radio on the bench the failing radio can be heard but just has no power to the signal on am or ssb. tx light does go to red when the mike is keyed and the audio is there but there is just no power out

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  • phil Ny Jan 12, 2013

    I can hear myself on another radio so I think that a lot of the transmitter is working. There is just no RF power.

  • phil Ny Jan 12, 2013

    It is not an oudio outpur problem; it is a RF power out problem.

  • Mike Charette Mar 05, 2014

    you should do an alignment on the radio . You can get the manual on CBtricks.com

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  • Expert
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If your receive is good and when you key the mic the meter goes to zero...im almost possitive your final is bad. Try it on side band usb/lsb if it transmitts good its the am final or driver.

Posted on Mar 08, 2015

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  • Cobra Master
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Final

Posted on Nov 04, 2013

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6 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE:

Hi there,
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Posted on Jan 02, 2017

SOURCE: cobra 148 gtl

First take a jumper wire and connect it to the DC Ground of the input of the radio then touch it to the TX pin on the radio if it does keyes up then its in the mic or mic cord on the end of the mic plug or where it goes into the mic cable goes up inside the mic. If the radio don't key up at all then check the main voltage regulator chip one pin will have 8 volts transmit and another pin will have 8volts recieve. If you get no switching DC voltage on the regulator then its bad and needs replacing there is also a known bad capacitor in the radio thats only 10 volts change it to 25 volts at the same capacitance.

Posted on Jan 08, 2008

  • 27 Answers

SOURCE: cobra 148 gtl stays keyed up on tx on both am and ssb

Your problem is a faulty changeover relay on the circuit board. It is a small black device , and may have the brand name MRATA
etched on it (the switchover contact points are stuck together)
WORTH A TRY GOOD LUCK
flyingfox@prople.net.au

Posted on Jun 22, 2008

  • 27 Answers

SOURCE: Cobra 148 gtl Low / No receive audio

No audio out / low audio out....This is a constant problem with the COBRA 148 gtl....to get a good level of volume replace the
electro caps ...start around the two speaker wires and work back from there. I'm in the process of rebuilding a 148 gtl and have found caps that are leaky and dried out...after replacing nine the volume went up to a good level...now i need to fix the distortion
and background hash. Did you know that there are many posts
on FIXYA about this same problem I.E. great TX , great PA but poor , or no audio out. these sets have been made in sevetal countries...The sets made in Taiwan or China have poor quality
front panel pots (the carbon track is micro thin and simply wares through to the material the track is printed on) This has the same effect as removing a wire from a pot I.E. no audio. The good news is that 99% of parts in the radio are freely available and that includes the front panel controls. ONE WONDERS IF THE SET IS WORTH THE EFFORT !!!

CHEERS GUYS / GIRLS.

Posted on Jul 03, 2008

  • 19 Answers

SOURCE: Cobra 148 GTL ST. No AM transmit audio. Carrier is

Could be TR41 or TR42. I would try TR41 first.

Posted on Jun 29, 2011

  • 4 Answers

SOURCE: I have a Older 148GTL, when I key down the mike

bit late, but for anyone else searchng for similar issues, test AM regulator ******, 2SA1012 - replace with good PNP, like TIP42c

Posted on Oct 04, 2012

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148 gtl receive works fine transmit has no power


Have you checked the 2sc2166 or the 2sc1969? Those are the RF Driver and the RF Final output transistors.

Jan 07, 2013 | Cobra 148 GTL 120-Channels Base CB Radio

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The 29 has a built in SWR meter--check the match to make sure it is below 2 (lower the better).

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If the squelch is up too high you will not hear people below a certain signal level---in your case set it so you hear who you want to and not jokers.

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Have a vizio vx 42l on the bench. amber light only no power up have my standby 5vdc and my 3.3vdc power button is sending a high pulse to the main mod but i dont get pson to the power supply mod suspect...


This is your mainboard needing replaced! Simple as that!

The main sends the pson signal and without it...you have a dead tv.


Please rate if this helped :)

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No modulation when transmitting


No modulation could be a problem with your mic or the factory setting inside the radio. Radios are set at about 50 to 80% modulation from the factory. This is adjustable in most radios. Search mod adjustment on XXX radio and you should get info as to where the mod adjustment is located inside your radio. Turning it all the way up will not hurt it but it could cause some distortion if turned too high. Up is turning it counter clockwise.
Modulation is not shown on all built in "S" meters, just power. There are bench meters which show both power and modulation available for about $50 and up.

Feb 21, 2011 | Radio Communications

1 Answer

My 2517 talks good after awhile on it it just drop out like dont have no mod but receive good let it cool it go back workin fine any idea? shows when this happens it shows on radio signal moving none on...


Hi and welcome to FixYa,

On a MOSFET version of a Galaxy DX2517 and assuming stock mic, heat related issues of missing modulation would require initial checks of:
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Good luck and thank you for asking FixYa.

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most likely you need to replace the mic. and maybe the speaker as well. how can you be sure it does not transmit when noone can answer you since you cannot hear them.

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Connex 4600 turbo. Poor receive. About 4 mi.


Hi there!!

The Connex 4600 Turbo is a very sensitive radio these radios don't work good at all with the stock microphone! The best microphones are the RK-56 and or the Astatic 636L which most people use and you shouldn't get any squeal. And make sure if that you are using an external speaker get it as far away from the radio as you can facing away from the radio so it wont feedback. As far as a Mod kit there are several ways to modify the radio which most are pretty hard and drawn out. but the most easy that used to be used is as simple as a diode placement in the right place which is old school but still works good. You must be very careful as if you are to slightly touch the wrong points the radio could be destroyed and no longer work so caution is to be taken if you don't know what you are doing please don't try it on an expensive radio!! If you want more info on the mod e-mail me

never the less a Modulation kit or modification wont help your Receive it will only help your Transmit signal!!

Dennis

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