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

Hello to the forum,

Working on my 2990 that just started acting up mainly in SSB mode and worse in USB.
Board number is EPT295013Z

Was working fine then after a few hours of just sitting idle I started transmitting to a friend on LSB and he informed me that is was not sounding good. So after listening to it myself I found that it was chopping or fluttering the transmit signal and audio. Everything I have tested and checked seems to be ok. So I guess I need some help to figure the problem. I have no test equipment to find where it is coming from other than listening on another radio across the room. Other than the chopping static sound it works ok. Any ideas anyone??

regards, Jim

Check than the driver bias is right.
Components known to go faulty C265, C292, D93, R254, R258, R304, and R305.
I have had D90 or was it D91 which gave bad audio on SSB, when the component was tested it tested ok but was faulty.

Thanks Rick,

I will test all those components you mentioned. I also have had things test good that were bad so usually If I pull it I just replace it. Saves time usually.

Regards, Jim

Thanks Rick,

I will test all those components you mentioned. I also have had things test good that were bad so usually If I pull it I just replace it. Saves time usually.

Regards, Jim

Jim you got the right guy on the job in Rick.

Amen to that brother, Rick is the man!!!

Thanks again Rick,
Don't know how I got 2 identical posts but anyway I replaced all the parts you mentioned and SSB is working ok but think I need to watch VR15 because it is a little nervous and jerky when I adjust it. Must have some bad spots.

Regards, JIm

If VR15 is a bit jumpy. Check C10 (4u7), or try spraying VR15 with some switch cleaner or just replace VR15.