Galaxy DX88 low power

[flatlander89]

For the pros.Ive been working on an 88 that had a no power problem.replaced finals with original 2312,driver,and pre driver.adjusted bias to factory specs.radio now has 4w.swings to 12 and looks awesome on the scope.not trying to get crazy watts or swing but numbers are too low for dual final radio.voltages look good according to the charts I have except only .3v on base of TR43 and-0.0v on base of TR56.replaced C209 and C171 with no improvement.Where should I look next?TIA

 

[Unit 75]

The first thing I would do is re-check your bias settings and make sure they are correct.(May be too low) Then check your AM Lo carrier pot and AM Hi carrier pot and make sure they are adjusted correctly as per the alignment procedure. 1-3w on low 8-10w on high.

 

[nomadradio]

12 Watts on what kind of meter?

If it's an average-reading meter, you're looking good.

If it's a real, live peak-reading meter, that's not so good.

73

 

[Low_Boy]

Where did the two 2312's come from? how about the 2166 Driver was that replaced or checked?

 

[flatlander89]

Thanks for the reply’s.that was peak reading with out modulation.2312s came from RFparts.forget if I got the 2166 from them or Barkett.readjusted bias settings to .64 volts at both finals base leads.still around 4 watt output.will do some checks tomorrow with the scope.thanks again for the help

 

[kopcicle]

.64 volts at both finals base leads

Volts? Try again

 

[flatlander89]

Yep.tried it that way and also 50 mA per final from tp9 to tp7 as specified in the service manual.any advice on setting final bias is appreciated also

 

[nomadradio]

Check C166. If the radio is old enough, it will be a 820 pf ceramic disc capacitor. They tended to overheat and fail. The factory began using a silver-mica part in this spot in the late 90s. Those take the high RF current better, and don't generate as much heat.

73

 

[flatlander89]

Sorry for the late reply.checked C166@ 833pf.