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Uniden pc244 off frequency

O

Ocean cruiser

Active Member
May 20, 2019
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Hello,
Just got a uniden pc244. Rx works but when transmitting, the frequency at the antenna is way off and doesn’t stay consistent. (24.4???) Checked it with a tenma 100Mhz freq counter and on a sencore cb42. Same result. What could be causing this? Please help. Thanks
 

one question about the out put freq with a counter. are you talking into the mic when you check the freq. if so stop doing it that way and turn the mic gain all the way down then dead key the radio and see if it stays on freq. I do not know the pc244 radio but does it have SSB and by chance are you checking it.
 
Man I can't find anything anywhere on the PC244.

I'm going to throw a wild guess and let people shoot at it .... :)

If you are receiving "on freq" then I would conclude that your PLL is working.

But in a number of radios, the VCO is dragged off and mixed with another oscillator to give you the resulting final output frequency. There may be problems in that area. But as I say... the world looks awfully dry on information on that radio. It isn't even on SAMS Photofact's list.....
 
I've rebuilt two of these radios and had to fix one of them that had other problems not like yours. Can't remember what I used as a schematic. I did some research and some say that it is the same schemo as a Uniden AX-144, which is available on CBTricks.
Perhaps some of the gurus will chime in here and impart their knowledge and experience for you . . .

But you will need a DVM and perhaps a real freq counter to troubleshoot your issues, as well as soldering equipment. Do you have that much?
 
guitar 199 - I will definitely check the vco

Robb - I do have access to those equipment and will check cb tricks.

Sonoma - I will see what happens in ssb also.

Thank you very, very much. Now I have direction. Have a blessed day
 
SSB will not be stable on freq with a dead key. make sure AM is stable with out any voice go to the radio. when you talk into the mic the freq will jump all over the place.. you said you are checking at the s0239 connector and in AM mode make sure you have the mic gain turned all the way off and just key the mic to see what freq it is putting out. as soon as you talk into the mic with the gain up the freq will jump all over the place.
 
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If your receive is working I suspect you will find it good.

I will be interested to see the results of the test with AM and no modulation!

If you were on sideband modulating your signal is going to be jumping around so much a counter is going to have a tough time locking on to the count and probably will look very low....

Ocean cruiser said:
guitar 199 - I will definitely check the vco
Click to expand...
 
Guitar 199

Did the AM test no modulation and freq is still off and fluctuating. These are the results I got:

VCO (TR20) Freq. 16.4876Mhz
B-2.42
C-7.69
E-1.82

VCO buffer (TR21)
B-2.56
C-7.56
E-1.85

OSC (TR22)
B-2.32
C-6.70
E-2.25

They seem close to the AX 144 specs I got off cb tricks. But let me know what you think. Thanks
 

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