The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

I have a President Adams CB. It's in great shape and doesn't look like it has ever had the case opened until I replaced a meter bulb in it. Problem is many of the channels are on wrong frequencies on both TX and RX. I'll try to clear this up better.

Channels that seem to work correctly are 1 to 7 ... 16 to 22 ...24 and 25 ... 35 to 40.
Channels on wrong frequencies are 8 to 15 ... 23 ... 26 to 34.

And there are duplicate channels .... for example channel 8 is the same as channel 16, 9 is same as 17.... here is a list

8/16 ... 9/17 ... 10/18 ... 11/19 ... 12/20 ... 13/21 ... 14/22 ... 15/? ... 23/? ... 26/36 ... 27/37 ... 28/38 ... 29/39 ... 30/40 ... 31/? ... 32/? ... 33/? ... 34/?

And this applies to all three bands .. AM/USB/LSB.

Any ideas what has happened and how to fix it? I don't have a frequency counter...yet.

how do you know the channels are all messed up, without a freq counter???

frogman296 wrote:how do you know the channels are all messed up, without a freq counter???

Because I have 4 other radios and when someone talks on the other radios down the road I can hear them on two different channels. And when I talk to them one of the channels that are messed up they don't hear me on that channel at all, for example I talk on 28, they don't hear me on 28 at all, they hear me on 38. They talk on 38, I hear them on 38 and 28.

It's screwwwwy!

Check the 10th bit of the LPP, Pin 17 to see if it's being switched on and off as you go through the channels.
It looks like you may have a broken connection between the channel change switch and the PLL's pin 17 as the 10th binary bit is missing.
Dave.

Thanks Dave! Your tip led me to checking all the connections from the PLL to the channel selector switch and I found two loose diodes from some pretty poor looking solder work. I fixed those two and touched up some other spots and the radio seems to be working great. Time will tell I guess. Thanks again! You guys here are awesome!

read this one, once i noticed that my 29 classic was doing the same thing only with different channels. 1-2 on 3a; 5-6 on 7; 11-12 on 13; 15-16 on 19a; 21-22,25-26 on 27; 31-32 on 35; and 35-36 on freq 27.515.

since I just resoldered a connection near the channel LED where part of the 9 was missing, I suspect i knocked another loose. (any idea which one, lol) will be testing.

Many times it is just the ribbon cable from the board to the channel selector, the wire has a high tinsel strength, so it breaks easily when you bend it, check both sides and I suspect you will find one or two broken. look closly, as the other wires in the ribbon will hold them close together....

Thanks redeye, good place to start. I probably knocked out one of the solder joints there when i was looking for the other bad solder joint