Cb superstar 2400 Mk2

check the am voltage regulator. you should have 12vlts on pin 1 ,4volts on pin 2 ,13 vlts on pin 3 . go to ( CB tricks .com ) its the same board layout as galaxy 44 . http://www.cbtricks.com/radios/superstar/3900/graphics/ss3900_sch.gif if you are looking at the board on solder side ,knobs faceing you ,it is located on top left hand corner ,about 1 inch down you will see the slot cut into the board .if you have vlt on pin2 less than 4vlts or higher than 8vlts its bad. Galaxy DX Radios DX44V Service Manual its (tr) 51
Galaxy DX Radios DX44V Service Manual

need to put it on an oscillascope and frequency counter and have it aligned. even taking to a shop should be less than $45 to have it fully done.

Check the position of the mode selector switch. You may be receiving a SSB (single side band) transmission that is not on the exact same frequency as you or, your radio is in AM or FM mode. You will need to select either USB or LSB (upper or lower side band) and vary the clarifier knob until the sound becomes intelligible. If the sound does not become clear, try the other side band and repeat varying the clarifier knob.

Conversely, if you are in USB or LSB mode and there is a transmission on AM or FM, it will have the same garbled sound. Try changing the mode to AM and the FM. If it does not become clear, it is likely a SSB transmission and you are not on the exact same frequency of the transmission you are hearing. Vary the clarifier knob until it becomes clear - or change to the other side band if needed and try the clairfier again.

The short story is that you must be in the same mode and on the same exact frequency. When in AM or FM, this is less of a problem as these are much more wide banded signals than SSB signals.

The 2990 is really a 50 watt 10 meter amateur radio - but is geared to CBer's as it is easily modified to work in the CB frequency range and the so called "free band" between USA's CB (11 meters) and worldwide amateur 10 meter bands. Be careful transmitting this radio on CB frequencies as it violates FCC rules for power output there - and transmitting in the 28MHz - 29.7MHz requires a valid amateur radio license. Fifty watts on ham frequencies is tiny compared to the 1500 watts permitted. Why not get your ham license (here's how) and leave the "Chicken Band" (and all it entails) behind. You won't miss it!

I hope this helps and good luck!

The FM has no forward modulation. You're radio will key up but you can't transmit on it. All cb radio are like that after conversion.

FM - Freq. Modulation

AM - Audio Modulation

USB - Upper Side Band

LSB- Lower Side Band

CW- Morris Code

is it steady output on AM with no modulation swing. then change the Audio transistor. SSB should work. they feed straight through to rf final. if no modulation on either mode, then check the mic, audio ic preamp.

FM is just a form of modulation, not an actual frequency. The frequency doesn't change between any of the modes (LSB, USB, AM, FM, CW).

For example, if you are on channel 19 (27.185MHz) on AM (Amplitude Modulation,) switching to FM (Frequency Modulation) mode you would still be at 27.185MHz, but using a different form of modulation.

most likely been fiddled with and out of alignment. If you have a freq counter and a volt meter you could possibly fix it yourself. look at cbtricks.com for the aligment procedure.

Check to make sure that the radio is on AM not FM or LSB or USB. There is Also a power control on the front of the radio turn it up half way and see if this might be your problem.If it still does not have any power out put,put the radio on usb or lsb make sure that your modulation is turned up and talk into the mike to see if you have any output.If you do have output on ssb mode the am regulator is most likely bad. ( Q 51 & Q 53) wich is located in the right hand side of the radio.

Hi Mate, the problem you are having in not uncommon in the
COBERA 148 GTL. I suspect that the problem lies in low value uF electro caps drying out (electrolite) causing power down and frequency drift. The capacitors are in two forms..tiny blue tantalum, and standard radial base caps that are grey aluminium
cans with a black stripe,it would be a job for a skilled person in electronics to replace all of them. The square metal cans with a screw ferrite slug are what you use to tune the radio, and as there are lot of them ,and you don't have a circuit diagram ,it would be pot luck finding the right one/s. What you realy need to know is all electronic devices age and hence, no longer do their job.
it would cost more than the set is worth to rebuild it,but if you have the skills ,it can be done. am cb with usb / lsb are a thing of the past now and you would be better off buying a used set that is still in top working order. The uhf sets are useless as was the am sets depending on what you want the sets to do, in convoy.... great....in remote country....useless. Having said that the am/usb/lsb sets are the best of the three because on ssb they tx on about 12 watts rms so you have a better chance of making contact, but don't count on it as hf cb is no longer in
common use.
GOOD LUCK [email protected]