Dear Everett et al,

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There are those that believe a Pi-Wound, or even

a Solenoid-Wound inductor is the Saving Grace of

QRO amplifiers.

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And there are those who think that monsters are

really hiding in their granddaughters’ closets, and

that hidden, destructive parasitic oscillations

reside, ready to lash out on unsuspecting operator

equipment.

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Both camps are correct. RF energy behaves more like

sub-atomic particles riding waves of phase change

DC energy, excited somehow in more direction

than only one, and possible at the very same time.

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Modeling software is only a test to see if something’s

kosher or not at a readily recognizable set of params,

so what, and why did my amplifier, after hours and

hours of QSY everywhere and outside antenna follies,

decide to go, “BINK!” and leave me with a $5,000

set of ceramojunk? “ Parasitic Oscillations,” the

well-remembered AG6K would say, while his close

friend(s) would say, “Hogwash!,” and both were right?

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(I still have small rolls of Nichrome 30 and Nichrome 60

if anyone needs any.)

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The circuit recommendation to avoid hi-impedance

pathways is achievable by a method to bolster the ampacity.

Using something with a wide bandwidth helps.

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Most Pi-W’s use microscopic wire.? Some Grid Anomalies

may induce a bolt of juice in them tubes, there, of Just

How Many Amperes Wre You Thinkin’?? Bazillions?

You may be right, but how long was that for?

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In that infinitesimal slot your Pi-W’s windings are going

to heat up, maybe in more than one place, and what’s

next? Current Down, Voltage Up: Goombye Grid.

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It might as well be mentioned a nice fat slug of copper

wire in between every G1 tube socket and chassis ground

for as short a distance as possible makes a reliable

addition to the design of all.

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Tetrode rigs, especially Grid-Driven behemoths, need

great bypassing on their tube sockets. Now thems are

serious monsters under the bed.

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Hal Mandel

W4HBM