RCI 2995 DX low power

[Crambone]

I had no power, changed out Q66, Q67 and one capacitor, now I have low power only around 5 watts swinging to 20 watts. RF Power is all the way up, followed alignment procedures but that’s all I’m getting from it.
Any help we’re to look for issue?

 

[TheRealPorkchop]

If 66 went bad then it’s possible it pulled a final with it, have you checked that yet? Possibly you’re running off just the driver or pre-driver maybe?

 

[Crambone]

If 66 went bad then it’s possible it pulled a final with it, have you checked that yet? Possibly you’re running off just the driver or pre-driver maybe?

Ya I figured, I’m going to check them after the holidays. Grandkids and family don’t leave much down time for me.
Have a Merry Christmas

 

[Crambone]

If 66 went bad then it’s possible it pulled a final with it, have you checked that yet? Possibly you’re running off just the driver or pre-driver maybe?

OK I checked Q60 - Q67 and all looked good but Q60. I removed and it showed bad so i replaced with a new 2SC2312C (NPN)but still showing an issue.
On the collector in RX and TX Im showing 3.3/ 3Vdc. On the Base Im showing 0/ 0 on RX and TX. and on the emitter 0/0vdc on RX and TX.
I checked the D91 by lifting a leg and it shows good.
I believe i should be showing around 4Vdc on the Emitter in TX leaving me to believe Im not getting current or power or signal to the Base????
Am I correct in that thinking? The Q60 i removed showed as a single diode on my tester?

 

[ExitThirteen]

The voltage on the collector of Q60 seems a little low.... with the RF power all the way up, it should be in the 5-7V range in AM. And yes, you should be seeing some voltage at the base of Q60. It should be very little, but you should see some voltage. It is possible that Q62 (2SC2166) has gone low gain due to being damaged by the failure of Q66/Q67. I have seen that happen before. It's rare, but it does happen.

If you have a scope, I'd recommend tracing the signal in each stage just to make sure each stage is indeed amplifying the signal.

There are 4 stages to check. The buffer (Q64, junction of C242/C243/R282/R283), pre-driver (Q63, junction of C237/R278/R279), driver (Q62, junction of C234/C291/L31), and final (Q60, junction of C227/C289/L27). If all the stages are amplifying as they should, you should see an increase of signal on the scope in each stage. If not, you may have a transistor that has gone fault.

Based on the voltages you're getting on Q60, it sounds like there's still a fault somewhere in the pass regulator section (Q66/Q67). You should be getting 5-7V on the collectors of both Q60 and Q62 in AM mode, while SSB modes should have anywhere from 12.5-13.5V on the collectors of Q60/Q62.


Do these tests and let us know how you get on.


~Cheers~

 

[Unit 75]

See if you are still getting 5 to 20 w out of the radio if you unplug the brown and black wires at J22. This disconnects the amplifier.

 

[Crambone]

The voltage on the collector of Q60 seems a little low.... with the RF power all the way up, it should be in the 5-7V range in AM. And yes, you should be seeing some voltage at the base of Q60. It should be very little, but you should see some voltage. It is possible that Q62 (2SC2166) has gone low gain due to being damaged by the failure of Q66/Q67. I have seen that happen before. It's rare, but it does happen.

If you have a scope, I'd recommend tracing the signal in each stage just to make sure each stage is indeed amplifying the signal.

There are 4 stages to check. The buffer (Q64, junction of C242/C243/R282/R283), pre-driver (Q63, junction of C237/R278/R279), driver (Q62, junction of C234/C291/L31), and final (Q60, junction of C227/C289/L27). If all the stages are amplifying as they should, you should see an increase of signal on the scope in each stage. If not, you may have a transistor that has gone fault.

Based on the voltages you're getting on Q60, it sounds like there's still a fault somewhere in the pass regulator section (Q66/Q67). You should be getting 5-7V on the collectors of both Q60 and Q62 in AM mode, while SSB modes should have anywhere from 12.5-13.5V on the collectors of Q60/Q62.


Do these tests and let us know how you get on.


~Cheers~

OK guys I found it! Radio was way out of alignment! After tracing the signal around the reading getting amplified but very little. Once i adjusted the output power of VR15 everything started to line up for me. So i went and did a alignment and we are back in business.
I bought this radio not working so it was a good feeling to fix it, I cant thank all of you enough!!!!!!

 

[Unit 75]

Nice going bud!

 

[Crambone]

Would have never been able to do it without everyone’s patients, guidance and support.

Thanks again, 73’s