-----Original Message-----
From: Richard (Rick) Karlquist
Sent: Friday, August 31, 2018 7:13 AM
To: Jim Thomson ; Guy Olinger K2AV
Cc: TopBand List
Subject: Re: Topband: Air Wound Coil
<I am sure that flat conductors result in lower Q than round conductor.
<I have done innumerable Q meter measurements to confirm this.
<I didn't say that flat conductors don't work at all.
73
Rick N6RK
## What are you using to measure Q ?? I did discover one anomoly with
coils
and Q. XL increases as freq increases. XL= 2 pi * F * L. However,
Q = XL / ESR.
ESR, due to skin effect, only increases to the sq rt of the ratio of the
freqs involved.
IE, 10m has double the ESR that the same coil has on 40m.
## A say 5 uh coil has DOUBLE the Q on 28 mhz... vs the same 5 uh coil
on 7 mhz.... go figure.
However, the same 5 uh coil will handle double the RF current on
40m..as it will on 10m.
## I have 2 of these .375 edge wound rollers. The 2nd one has less uh,
but has a nice tapered pitch
at one end. 50 uh vs 40 uh. I strap out the excess with those clips.
22-24 uh used on 160m. Its all
shorted out when on 20-17-15m..as an outboard .375 tubing coil is used on
those bands, tapped with a
modified HV solenoid. This is on a hb amp. 17 + 15m share the same tap.
Jim VE7RF
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