Cobra 148 NW ST Bad SSB TX audio [A FIX]

[FreeIPTV]

I checked the forum but did not find anything related.

I picked up two of these in clean condition and after some minor alignment i thought they worked ok for a poorly built radio, I even added a PIC chip to the not so good condition radio to give me an extra +40 channels [27.415 to 27.855] and a +10kc switch, Then i replaced the covers and noticed that SSB TX audio was bad, With the cases off audio was good, After a few hours of working in the RF final section i got nowhere, Then i noticed the regulator was a KIA7809 so i thought about replacing it for a 7808 and lo and behold it worked no more bad audio with covers on, If you replace this regulator L21 [USB] L22 [LSB] L23 [AM] will have to be realigned.

So there you go, I hope this information may of be some use to anyone who owns one of these radios.

 

[sonoma]

good find, 1st I have heard about the regulator being weak causing problems. will be good for any one else. will make a note of this for future reference.
were these the front mic or side mic radios. a few of the front mic radios after a peak and tune will sound bad on SSB. could be a common fix for them

 

[melaza]

I checked the forum but did not find anything related.

I picked up two of these in clean condition and after some minor alignment i thought they worked ok for a poorly built radio, I even added a PIC chip to the not so good condition radio to give me an extra +40 channels [27.415 to 27.855] and a +10kc switch, Then i replaced the covers and noticed that SSB TX audio was bad, With the cases off audio was good, After a few hours of working in the RF final section i got nowhere, Then i noticed the regulator was a KIA7809 so i thought about replacing it for a 7808 and lo and behold it worked no more bad audio with covers on, If you replace this regulator L21 [USB] L22 [LSB] L23 [AM] will have to be realigned.

So there you go, I hope this information may of be some use to anyone who owns one of these radios.

Hi,

Change C172 from 1000uf to 2200uf.

 

[FreeIPTV]

Front mic socket version.



PIC chip installed for +40 and +10kc

 

[sonoma]

thanks alot for the info. I have one that the SSB is not clean on TX so may try the 8 volt reg. already tried the c172 cap mod. it did help a little bit. there is a mod for what guys call a warble on this radio to put power to the audio ic and the regulator by changing how the 12 volts is fed to them. tried that mod on a radio years ago and it helped a lot also. but takes a while to do the mod and if a guy is not good at cutting a trace and jumping the power it can mess up the radio.

 

[sonoma]

channel setup looks very clean. how about showing how you did the board with the chip for the install.I would like to try it if can get the info from you for the mod and what chip you used and coding to get the channels.