On Tue, 30 Nov 2004 19:47:48 +0000 (UTC), David Snyder Hale
wrote:

I haven't been able to find any reviews of the Miracle QPak antenna
tuner. Does anyone have experience and comments?

Their web page makes it sound like they are finally bringing amateur
radio out of the dark ages of tuners, but is it all that?

Does this look like $150 worth of parts?

http://www.miracleantenna.com/QPackinside.htm

???

Bob
k5qwg

It's not obvious to me why the reactance of the link needs to be 50 ohms
(for a 50 ohm resistive source) to be "ideal for the maximum transfer
of power" in a conventional link coupled tuner, as VA2ERY says on the
web page. Maximum transfer of power requires only that the input and
output impedances be properly (conjugately) matched (and, of course,
loss to be minimized), and that doesn't require the link reactance to be
any particular value.(*) The argument for the supposedly wonderful
performance of the tuner seems to revolve around solving this "problem",
and it falls pretty flat if it's not a problem at all.

Can someone enlighten me as to why the link reactance needs to be 50 ohms?

(*) The capacitor and inductor voltage and current can be traded against
each other by changing the L/C ratio. Depending on the particular
components used, there'll be some ratio at which loss is minimum. But
this depends on the components, and not some universal value. And it
would have no effect I can see on the transfer of power, which requires
only a conjugate match.

Roy Lewallen, W7EL

Bob Miller wrote:
. . .

http://www.miracleantenna.com/QPackinside.htm