[Milsurplus] Smart People: BC-9A Opinions Needed

[AKLDGUY .]

That's strange. I'll swear the circuit diagram had no + and - markings for
the 120-V
battery terminals when I looked at it earlier. In any case, the battery
symbol is still
shown back to front, despite the markings.

73 de Neil ZL1ANM


On Wed, Jan 4, 2017 at 5:55 AM, AKLDGUY . <neilb0627 at gmail.com> wrote:

> Hi Dave
>
> I believe you have the polarity of the 120-V battery back to front. The
> way you have it would put -ve
> onto the first tube's plate. The green wire in my opinion is the effective
> "Ground".
>
> 73 de Neil ZL1ANM
>
>
> On Wed, Jan 4, 2017 at 4:51 AM, David Stinson <arc5 at ix.netcom.com> wrote:
>
>> Good morning.  There's precious little specific information technical on
>> the WWI-era BC-9A
>> (SCR-77A) battery-operated, portable CW set.
>> Some general descriptions but no clearly-copied schematic.
>> https://goo.gl/photos/uVYek56Zoja1jqQq6
>>
>> There is a schematic on the inside of the cover, but mine was stained and
>> missing a large part
>> of the center of the diagram.  I have worked with what I could find to
>> re-create the diagram.
>> Please look at this photo.  The re-created part
>> is in the green outline.  It is close to the smeared,
>> obscure copies I've seen but not certain.  Does
>> this circuit make sense to you?
>> https://goo.gl/photos/RCMKFHrZKZBHoeLc7
>>
>> Next:  I'm working on power supply solutions
>> (other than the obvious batteries.)  I need to do some RF bypassing in
>> the supply lines and need
>> a point I can call "Ground" in this circuit.
>> This diagram- Red lines appear to me to be
>> what one would think of as "RF Ground," while
>> the 120 and 40 B- lines reference in green.
>> That puts B- above the "RF Ground" by the filament bias, adding to the
>> grid bias on the tubes.  Do you think my analysis of
>> the red line being the place I could think of as "Ground" is sound?
>> https://goo.gl/photos/bucwyMuC12jdfWWT7
>>
>> Thanks for your input and prosper in 2017.
>> 73 DE Dave AB5S
>>
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