[TMC] GPR-90RXD stuff

[Chris Bolkan]

The drawing does show the wire gage and overall inductance if I
remember correctly, so with resistance between windings it should be
able to be reproduced. I'm just trying to get to the bottom of it!
Chris

On Fri, Aug 6, 2021 at 2:15 PM James A. (Andy) Moorer
<jamminpower at earthlink.net> wrote:
>
> If somebody has an L38 from a parts unit or is willing to unsolder
> theirs, you can use a modern ohmmeter to figure out where the tap is.
> There won't be a lot of resistance, but the ratio of resistances from
> tap to end points should be related to # turns. That plus the overall
> inductance should be all you need. Hmm. I wonder how critical the
> winding technique is? Basket-wound versus pi-wound? The point of those
> "loose-looking" winding techniques is to reduce the self-capacitance of
> the windings. You can wind one by hand, or on a vintage Miller coil
> winder if you can find one and figure out how to make it work.
> -A
>
> On 8/6/2021 5:01 PM, John Poulton wrote:
> > Just for the heck of it, I looked up the drawing for this coil (L38, BFO
> > output coil).  From the parts list, it's TMC part # CL-231, which is also
> > the TMC drawing number.
> >
> > Here's the drawing URL (I've scanned most of the drawings for smaller coil
> > assemblies):
> >
> > https://tmchistory.org/tmc_drawings/drawings_db/cl/cl_200_299/cl-231.pdf
> >
> > The drawing is singularly unhelpful.  It shows a 3-rank pi-wound coil with
> > an inductance of 585uH (in agreement with the schematic, but not the parts
> > list) with a powdered iron core, but it doesn't even mention a tap or
> > indicate where it might be..  Arghhh.  Maybe the wire type and Q will be
> > useful to you.
> >
> > Chris, hope you're able to find a photo of the coil.  I'd be interested to
> > know what you find out from it.
> >
> > 73, John K4OZY
>
>
> --
> James A. (Andy) Moorer
> www.jamminpower.org
>
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