Another Saturn bias issue

[brandon7861]

Is it possible that the very low resistance you measure between the base and emitter is due to the VR's being set to zero? I know there is still a 1ohm resistor that should be showing up, but maybe reverse the ohm meter leads so its not letting the B-E junction share some of the meter current.

If this explains away the low resistance, I think Bayou might be right about the bias diode's Vf.

 

[nomadradio]

Gotta take one leg loose to check the bias diode. The circuit resistance in parallel is too low to obtain a meaningful test of the diode in-circuit. Just won't work.

73

 

[Hawkeye351]

Got it...

Output now:
AM carrier - 1w up to 12w
AM swing - 55w PEP
SSB - 45w to 50w

Reworked entire driver/final section, replaced all three bias adjustment VR's, triple checked solder work.

Factory bias network still intact, except I used 4148 diodes for bias diodes.

Radio reports on the air is "It's loud hawk and has a strong carrier".

Thank you guys...

Now I'm gonna write down the steps to do the bias as y'all said on my personal Saturn. My Saturn works great as it is, but I'm gonna use mine to experiment with this bias rework y'all posted.

 

[BayouRadioAmplifier]

OK, cool! cool beans!

after I get one of them working, I adjust for 10 watts carrier
and you get the full 40W PEP with modulation.
and for SSB, the same 40W PEP output.