[ARC5] ARC-5/SCR-274-N receiver bandwidth spec

[J. Forster]

If the washer is metalic, even brass or aluminum, it will decrease the
mutual inductance between the coils, thus narrowing the 'rabbit ears'
response curve or narrowing the BW.

My *GUESS* is that the coil assemblies were built, tested, and aligned in
some kind of a test fixture, and only then installed in a receiver. That's
at least part of the reason they plug in.

Furthermore, If someone took a random known good receiver, removed the
coils, and plugged them into another known good receiver of the same type,
I'd expect the second receiver to be in pretty good alignment.

YMMV,

-John

===============



> Gentlemen,
>
> Continuing with my ARC-5/SCR-274-N receiver IF coil mod investigation, I
> just completed yet another 80 meter coil set, this one from an
> ARC-5/R-26.  In doing so, I find yet another mechanical set-up in these
> coils.  This one has the long brass screw (up from the bottom) and
> threading into the phenolic spacer bar (vice using a nut).  All else is
> the same as other coil sets and I find that coils sets are, so far,
> interchangeable.  The question for today is what is the original
> published (sic) receiver bandwidth of this receiver?  I'd like to know
> what the starting point should be, even though I'll be measuring
> unmodified and modified sets.  At this point, I can again say that there
> /is/ a detectable improvement in selectivity.  What remains is to
> quantify things and, as we speak, I'm proceeding with the procurement of
> a suitable sweeper.
>
> Another point of possible interest is the fact that in each and every
> coil set there appears a 1/2" disk "shield" positioned between the upper
> and lower coil bobbins.  Could this be what others have spoken of as a
> method of providing electrical separation (read: increased selectivity)
> between these coils?  If so, then someone back then was thinking.........
>
> Regards    Jeep - K3HVG
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