Frequency counter displays two digets high from hump on fine clarifier adjestment on usb.27.186 insted of 27.185. also in am mode shows dead on with clarifer hump until mic is keyed thin dropes from 27.185 to 27.184 lsb seams stable. thanks

An external freq counter will always do a better test then the one on the unit . Do you have an oscilloscope? A function generator will also have a freq counter . Now the ultimate is a spectrum analyzer. you don't need all these but the function generator will work fine.

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!

that one diget doesn't mean anything as long as the diget after the dot remains steady.

Volume/Squelch control: As desired
ETone: Sets the sound of the echo as desired
MicGain/RF Gain control: Normally, leave fully clockwise
Band Switch: for CB, turn all way to left (a/e)
Mode Switch: Selects how you modulate the radio. Normally, you will operate on AM, USB or LSB.
Fine/Coarse control: Changes the frequency you operate on. Normally, set so the frequency counter reading ends in 5. (center slot of the channel).
Buttons:
RB: Roger beep. Turn on or off as desired.
NB/ANL: Noise limiters. Leave on.
Frequency Counter: Turns counter lights on and off.
+10 KHZ: Allows you to get the channels missed by the Channel knob. Normally, leave off.
Power: Selects either high or low transmitter power setting.
Band: Selects band of operation. Low (A-D) or High (E-F)

Adj VR1 next to VR2 they are in the center of the main motherboard. VR1 will allow you to adj the S meter in AM mode only.

Ok! well i deffinitally know what the problem is. You need to play with the clarifier, i think all the way to the left is a "course and fine tune" knob. This is generally for use when talking on SSB. but may affect AM if its way off.

The clarifier lets you slide on the freq. some radios will go a full channel some will only go a little or above the center of the channel. You need to play with the clarifier, you probably need to turn the course a lot, untill the audio is almost clear on the channel you want to talk on, than use the fine to tune it in so it sounds like they are sitting right next to you.

what you should do is buy a Frequency counter, you got a nice radio, so the freq. counter wouldent hurt. lets say you want to be on channel 19. you would turn the clarifiers untill i read 27.1850 That would put you right on the money

U mean on sideband? Frequency counter only useful on other than sideband operation. This does not mean the carrier insertion osc. is on frequency. If it needs adjustment, your voice will sound high/ low on transmit. Incoming signals will sound right after adjusting the osc.

You'll need to connect Frequency Counter to C252 & adjust:

USB Frequency: 10.6975Mhz adjust L126 in receive mode
LSB Frequency: 10.6925Mhz adjust L127 in receive mode

ghilger, First off, has your radio been converted to open up all the other channels(including CB)?? That has to be done first, or it's locked in the ham freq's. I think the factory manual is pretty well detailed, but i've been around radios my whole life. The mode button does the changing from am/fm/usb/lsb.Here's from the manual;

MODE: Operating Mode. Press the MODE control to select the operating mode. The operating mode is indicated on the liquid crystal display: am, fm, usb, or lsb.
* See, there is 2 different functions for each button. One set of functions are by just pushing the buttons, the other set of functions are obtained by pushing the function button first. The function button is activated by pushing in on the clarifier knob.
*Here is for saving of freq's;

Memory Save. To save in memory a specific
frequency and operating mode, select the desired mode and rotate the FREQUENCY control to the desired frequency. Press the FUNC button, and then press the M.SAVE button. S will appear on the LCD next to the frequency. While S is displayed, immediately press any of the memory channel buttons (1 - 5). The mode and frequency is now saved into memory. If the S indicator disappears before you press the memory channel button,
the information will not be saved and the process
must be repeated.

M.LOAD: Memory(Recall). To recall, any of the saved memory channels press the M.LOAD
button. L will appear on the LCD for several seconds. While the letter is displayed press the desired memory channel button (1 - 5). The programmed mode and frequency will be displayed.,
If you have any more questions about the radio, repost them here and I'll try to walk you thru them. The radio is a very good ssb rig, especially set up with a power mic. Hope this helps,, Mechanic