ORIGINAL MESSAGE:
On Sat, 13 Mar 2010 21:42:46 -0500, "Carl" <km1h@jeremy.mv.com> wrote:
> The Q of the strap, wire, coil, has nothing to do with the design.
>This is where the voodo starts.
REPLY:
This is the crux of the argument presented by the anit-Measures
naysayers. Measures claims, and I agree, that a nichrome wire coil has
lower Q than a copper one, and especially so when skin effect is taken
into account. Skin effect increases with frequency and can be quite
pronounced at VHF, one of Measures' primary considerations.
How important that is is open to debate, but to just dismiss it as
having "nothing to do with the design" is careless, IMO.
Having said that, I must also say I don't completely agree with
Measures' conclusions that copper wire coils are a real problem. The
great majority of Q-lowering is done by the resistor(s), and done
properly, that is almost always enough. If one wants to add more
Q-lowering by using nichrome wire for the coil, be my guest. It can't
hurt and it could help.
Electronic design is often as much art as science, and this area is
clearly an example of that.
73, Bill W6WRT
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