[ARC5] SCR-183/-283 4-5 MC Coil on 75 MTRs

[AKLDGUY .]

Referring specifically to the BC-xx-230 model:

How does one determine the setting for the roller inductor?
Has anyone tried using the 1626 triode for VFO and PA?
If so, what B+ and bias resistor did you use?
What is the optimum 1626 PA plate current for CW?

Any other useful hints?

73 de Neil ZL1ANM


On Thu, Jul 3, 2014 at 11:55 PM, <jmfranke at cox.net> wrote:

> If needed, I have two 3.2 to 4.0 MHz coil sets. One is a C-382, for a
> BC-AR-230 or BC-AR-430 and the other is a C-217, for a BC-AH-230. I also
> have a C-383 4.0 to 4.495 MHz coil and several 40 Meter coil sets as well
> as coils sets for below 3.2 MHz.
>
> John WA4WDL
>
> ---- David Stinson <arc5 at ix.netcom.com> wrote:
> > 4-5 MC coil sets for SCR-183/283 transmitters
> > (BC-230/-430) are very common, while those that
> > cover 80/75 Mtrs directly can be hard to find.
> > The OSC section of the 4-5 MC coil set will operate
> > down to around 3750 KC, but the PA/Antenna coil
> > is pretty much done at 4 MC.
> > http://home.netcom.com/~arc5/SCR-183/coilplate.JPG
> >
> > You can get the 4-5 MC coil operational down into
> > 75 meters with a few simple, non-destructive changes.
> > Move the Antenna coil tap up to the second turn from
> > the top.  Pad the coil from the tap down to the bottom
> > using either a 50-100 pFd transmitting doorknob
> > (Thank you, Mike!)  or big, RF-rated silver mica.
> > Don't use a ceramic; too lossy.
> > http://home.netcom.com/~arc5/SCR-183/coilpad.JPG
> > (yes, yes I know it's sloppy.  I was prototyping, guys!)
> >
> > Assuming you use a 100 pFd RF-rated or air variable
> > cap in series with the output to feed a 50-ohm load,
> > you'll find the tap for best output around here:
> > http://home.netcom.com/~arc5/SCR-183/coiltap.jpg
> >
> > You will get about 10-20% less power out than
> > you would with the "correct" 3-4 MC coil,
> > but then most of us don't have that one ;-)
> > A working rig in exchange for 10% is a good deal.
> >
> > 73 DE Dave AB5S
> >
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