Rci 2990 will not key up. - Radio Communications

I think you will find the problem is in one of the microphone wires. The switch for TX/RX is in the mic, and if the RX wire opens up, you will not get any receive audio.

something to do with powering up the radio from a cold start

Mic Wiring Info
Stock Mic Wiring
1. Ground Shield
2. Audio Yellow
3. Transmit Red
4. Receive Black
5. CH. Up White
6. CH. Down Blue

If on all modes check the mic first to see if wired right or wires broken--this should have am-fm-lsb-usb---which works or do not work.

Check the RF output transistor, usually heatsinked to the inner chassis, microphone wiring needs to be checked for breaks since it is part of the circuit, sub another if possible.

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!

• These boards are hard to find. If any place stocks them new it is Maycom http://maycomcomm.com/ I have bought lots of Galaxy boards from there.

• I have also gone chicken hunting before and just start randomly calling CB shops and see if they have one for sale from one of their parts radios. One time I could not find a heat sink anywhere and they were going for $25 new if one did pop up somewhere. I landed 4 like new radio heat sinks with hardware shipped for $10. So this method can pay off with some persistence.

• Also the board out of a Galaxy 2527 or an RCI 2990 will work as well. Ranger often stocks these parts too you just have to already know this. So give them a ring too http://www.rangerusa.com/ and ask about the RCI 2990 board. Of course I recommend you exhaust all options for the OEM board first.
  

• Hope this helps.

you have hooked it up backwards. You blew the polarity protection diode. It needs to be replaced.

http://www.rangerusa.com/websupport.html

http://www.worldwidedx.com/cb-band-cb-radios/18036-manual-rci-2990-a.html

you may find some help with these sites

the voltage controlled oscillator (VCO) is out of alignment.