[Collins] Need advice: diode load output on R-390A

[Dr. Gerald N. Johnson]

On Mon, 2009-10-05 at 19:55 -0500, Tom Frobase wrote:
> Dr. Gerald N. Johnson wrote:
> > On Sat, 2009-10-03 at 10:05 -0700, C E wrote:
> >   
> >> All:Does this diode load output on the R-390A require a preamp? I would like to homebrew a 6V6 single ended amplifier to obtain better audio output.  Inquiring minds want to know. 73 de Cal, n6KYR/4
> >>
> >>
> >>       
> >>     
> > A 6C4 might be a better choice given the audio phool mentality these days.  There is also a mod floating around that replaces the output tube with a 6AQ5 giving a nice solid 5 watts output. ... tom, N3LLL
> > Usually a triode like a 6AT6 (half a 12AX7 would be
> > similar) to develop the 12 volts or so peak that the 6V6 needs. The
> > detector probably puts out no more than half a volt. And that's what is
> > at the diode load. The typical first audio triode has a mu of about 100.

The 6C4 has a lot lower mu as I recall and so its not so much used as a
first audio, sometimes as a split load phase inverter for driving a pair
of pentodes. In that application the voltage gain is about 1 to the
cathode and -1 to the plate because of the large cathode resistor.
> >
> >
> >   
> 

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer