Roger,

I presumed it (the BFO) was not working because

a) There is no audible evidence of function, that is, it is not
producing beat notes against CW

b) I tried probing in that area with a scope and saw no evidence of
oscillation

c) I injected a sine wave from an external signal generator into that
circuit, and could then make out CW notes.

You might be right, it might be working but at the wrong frequency. On
the other hand, item (b) suggests it's not working at all.

73
Pete
AC7ZL


Roger D Johnson wrote:

H. P. Friedrichs wrote:


I cannot seem to get the BFO working, however. The resistors around
the BFO seem to check out ok. The condition of the caps are unknown at
this time, though I have not run across bad silver micas or the pF
dogbones.


How did you determine that the BFO is not working? I'm thinking that
it might be working and just off frequency due to bad caps.

73, Roger

H. P. Friedrichs wrote:
I presumed it (the BFO) was not working because

a) There is no audible evidence of function, that is, it is not
producing beat notes against CW

b) I tried probing in that area with a scope and saw no evidence of
oscillation

c) I injected a sine wave from an external signal generator into that
circuit, and could then make out CW notes.

You might be right, it might be working but at the wrong frequency. On
the other hand, item (b) suggests it's not working at all.

What are the plate and cathode voltages on the BFO tube? I am thinking you
might have a bad resistor.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."