[R-390] Yet another question... sigh...

[n4buq at knology.net]

Still mulling this over.  Injecting a 0.1V modulated 455kc signal at the 
plate of the detector (V506) isn't giving any output.  If I inject 0.15V 
audio at the grid of V507, I get the expected results so the table says the 
problem is in the detector circuit.

What I can't figure out is the radio does play -- perhaps not to 
specification, but it does play so I'm curious how the problem could be in 
the detector.

Not sure where to go from here.  There's very little componentry around the 
detector (and I'm running a NOS tube there just in case) so it should be 
easy to spot if anything's amiss there.

Weird.

Barry - N4BUQ


On Sun, 17 Sep 2006 22:00:02 -0500, "Barry" <n4buq at knology.net> wrote :

> Well, some of my test equipment actually agreed for a change.  42mW 
measures
> 5V on my DVM.  Cool.  The audio tests were spot on.  Following the table,
> when I inject 0.1V of modulated 455kc on pin 7 of the detector (V506), I
> don't get the expected results.  The only difference in my test is my
> internal modulated signal is 800cps whereas I think the test states
> something like 400cps but I don't think that would really matter.  I 
suppose
> I can hook the audio signal generator to the RF signal generator and use 
the
> external modulator position, but, again, I doubt that would change 
anything
> very much.
> 
> According to the table, I have problems in the detector circuit.  I'll 
start
> looking there for problems.
> 
> Thanks, guys!
> 
> Barry - N4BUQ