Question about Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

When I key the radio the meter pegs in s/rf mode.

This is an old 148 that was in a motor home that was sitting for the last 15 years the face was green and the meter a little sticky,So a friend of mine put a new meter in it.Is their a potentiometer on the board that i can turn to fix that? Thanks Chuck. PS the radio was made in taiwan.

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  • cdz Mar 06, 2009

    It is the same meter,Their was no resistor between the terminals ,im still not sure what to do.

  • cdz Mar 07, 2009

    Thank you sir, That solved the problem.AAAAAAA+++++++++

  • cdz Mar 07, 2009

    Thanks that worked Thank you AAAAAAAAA+++++

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There is a pot inside the radio to adjust the meter. if the meter did not come from the same type radio then most likely it is not the right one all meters are not the same there is also a resister that jumps across the terminals of the meter that needs to be there to keep the meter from banging the side when you key the mic.

Posted on Mar 05, 2009

  • james morgan Mar 06, 2009

    FIRST REMOVE THE COVER ON THE SPEAKER SIDE OF THE RADIO.UNPLUG THE SPEAKER AND SET THE COVER TO THE SIDE. LOOK TOWARD THE BACK OF THE RADIO AND FIND VR6 TX SIGNAL. WITH A ANTENNA ON THE RADIO KEY THE MIC TURN THE POT WITH A JEWLER SCREWDRIVER AND ADJUST THE METER UNTILL YOU GET THE METER JUST BEFORE THE RED MARKINGS AND STOP. THE METER WILL BE VERY CLOSE TO SET AT THAT POINT DO NOT TURN ANY OF THE OTHER POTS THIS WILL MISALIGN THE RADIO JUST TURN ONLY THAT ONE.





    JAMES MORGAN

    MORGANS ELECTRONICS

  • james morgan Mar 08, 2009

    cdz



    glad i could help you. enjoy your radio and have fun doing so.

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1 Answer

How do I increase power output for a cobra 148 gtl the latest Chinese version


best way is to leave the radio in piece and obtain a linear amplifier to do the job a 10 meter ham radio amplifier will do nicely but you must re-tune it for the 27 mhz band 10 meter band is 28 mhz.
RF amps work best using side-band mode.

Oct 14, 2013 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

My cobra 142 gtl loses power about two minutes after keying the mic.


hi

it looks like the output stage is going hot (99%)

maby the swr is high end eficiancy is low

usualy on ssb the power is higher than on am


bernard




http://www.rylwy.com/

Aug 03, 2012 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

When i try to calibrate my 148gtl mk 2 the needle is very erratic,why?


can you be more specific please ?
TX meter or RX s meter ? check power supply voltage is stable,
obviously on RX its essential to use a constant signal, of course,
if you're doing it without test gear & just doing a quick 'tweak' comparing with a good know s reading off a known set - a s9 signal is usually the standard point they calibrate to. although on a CB set its not a greatly important. on TX you may first want to check RF power out is constant first, so a dummy load (in case aerial swr is changing while on TX) needs to be used.
If actual RF power is changing, suspect drying electrolytic capacitors, these sets are 30 years old, so its not unlikely. dying driver or PA transistors or dry joints are also possible. or if everything checks out, possible voltage regulation probs, so check 2SA1012 AM reg isn't dying and the other ****** too.
If you're lucky, its just the variable resistors giving up.

Mar 07, 2012 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

S/rf is too high on transmit on my cobra 29 ltd bt


no matter what s/rf you are looking at it should not key much beyond an s-9 . vr 3 controls the meter. Key the mic and adjust it to s-9 then check you modulation.If you still think you need more then adjust vr 4 .

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Radio quits after 15-30 seconds


without more detailed info, quick suggestion - thermal fault, if all TX audio works when in this fault condition, it may be fair to assume audio IC is ok and check electrolytic capacitors and dry joints.

Nov 28, 2011 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

Rf meter does not work


Does the radio have any rf output? Use a swr/watt meter to check. If if doesn't have any output that would be the cause of the problem.. then its another issues..
May need some test equipment to find the fault on that one.
You could send it in to us and we can fix it.
We do not charge to look at any radio -no bench fees-..
Let me know Ill get you any info that you need.

Oct 19, 2011 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

NO AUDIO / NO TX


OK bare with me now i have no idea of your knowledge level with CB/ SSB radios.
Lets make sure our setting on radio face is correct before we decide this is an mechanical problem.
Set the following
  • Volume knob 12 o'clock
  • Dynamike knob 12 o'clock
  • Squelch full counter clockwise
  • Rf gain full clockwise
  • Select S/RF position on the SWR/CAL switch
  • Select AM position on the USB/AM/LSB switch
  • Select CB on the CB/PA switch
Now there will be some critics with opinions on the next instructions. Place a small screwdriver or test lead from a multimeter in center conductor of antenna jack listen for onair noise or radios operators to verify RX is working. Now remove the antenna/screwdrive/testlead. Then key mic just long enough to notice if the meter is swinging do not hold the mic button long this can damage the final. I tell you to do it this way rather that connected to your antenna system so we can eliminate the question if it is you antenna sytem or the radio.
If the LSB or USB was selected when you keyed the mic you would see no meter movement this is due to the lack of a deadkey or carrier for SSB which is a much more efficient method of transmitting on AM.
There are few things that affected the rx and tx together.

Aug 16, 2011 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

148 GTL 120-Channels Base CB Radio: my 148 throws a key to my bench radio but sends no...


Hi
try replacing the transistor just before the last on the rf pa output.

Hope this helps

Ray

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1 Answer

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finals need to be replaced, as they are fried,, hence no output,,and if you are lucky you haven't fried the pre-amp as yet....as the pre amp is REAL EXPENSIVE....so stop keying it up

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