Transmits and receives no modulation out

could be your final , could be the modulation transformer, could be your coax, could be your mic. Hows the SWR . under a 2.0 I hope.the smaller the # the better you get out .

Without seeing it I would guess (and it's only a guess) that maybe you have a broken microphone wire. If it's a factory mic the most common place for it to break is right up from the mic plug. Factory cords are not flexible, their really stiff. We could really use some more information. Mike

'mic gain' adjusted for optimum amount of modulation?

I would turn do the watts to about 3.5 and that radio should swing.Sounds to me like its trying to but the wattage is stopping it.Experiment with it and find where you want to set it.

Make sure squelch is turned down enough---if meter shows signal and no audio the internal speaker may be bad (plug one into external jack on rear of the radio).

If the radio transmits and shows it (or someone can hear when you xmit) the problem is in the audio circuit of the radio.

Check internal/external speaker AND SWAP THE MIC as a mic with a broken wire inside or open element as well can cause this.

The problem is in the audio output chip usually bolted to the inner chassis. Sometimes the chip developes a hairline crack, replacement recommended.

sounds like your Audio Output went out......not audio chip....may be your voltage regulator also....your voltage regulator IC is heat sunk....do you have a schematic?

Okay.

You do set this up like a regular CB. The meters refers to how long the waves are. CB is 11 meters. So its very close. The antenna woud be tuneds slightly shorter. Use the SWR meter in the radio to calibrate just like you would a normal cb.

Now for the ABCDEF knob. each letter is 40 channels in the band. So A would be 1 - 40 channels, then B would be the next 1 - 40 channel frequencies. You use the frequency counter in the radio(providing that model has one) to tell what channel you are on.

Here is some info one the frequencies in the band.

Now for AM and FM. this is the type of modulation you are using for transmit and receive.

CB transmits on AM or SSB. Amplitude modulation or Single side band. Most CB radios only have AM. But some also have SSB. None will have FM.

FM is frequency modulation.

10 meter radios can have AM FM SSB and DSB depending on the model and options it comes with.

So your radio has 6 ranges for freqency. each is 40 or 50 channesl. Not sure what model you have. If it has 40 then you have 240 channel freqencies.

with AM and FM, you double that, because you can talk on AM or FM on all the channels. If you are on AM and some one transmits on FM unless they are really close, you will not hear them at all, but if you do with will just be garbbled noise.

Also Am and FM both work a little different with range etc.

Now, you may be able to talk on the CB channels as well. Cb starts at 26.965 MHz and ends at 27.405 MHz. The channels are all .010 MHz appart.

Hope this helps

Hi and welcome to FixYa,

Initially, pls confirm that there is modulation (transmit audio). The reason I asked is if IC4 (TA7222P) is blown, then the radio would have no audio amplifier which would explain no receive audio. Additionally, the final and pre-final (TR15 & 15) gets is modulated TX+12 through D8 from T1 which in turn is the output of IC4 through C48.

Perhaps a schematic diagram may be of further help.

Good luck and Thank you for using FixYa. Happy Holidays.

If the meter shows that it's receiving something, the microphone may be the problem. Another possibility is the speaker & plugging an external speaker in would confirm this. Aslo make sure the squelch control is turned all the way to the left (counter-clockwise) & the RF gain is turned to the right (clockwise).