Re: Antenna Tuner Kits/10 Meters / RF LIMITERS!

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From: Arjen Raateland, FEI/Impacts Research (Arjen.Raateland@vyh.fi)
Date: Sun Aug 16 1998 - 04:39:15 EDT


> On Sat, 15 Aug 1998 22:01:03 -0500 n9qil@juno.com (Kenneth R Wezeman)
> writes:
> >The numbers are on page 43 of the April, 1998 issue of QRP Quarterly.
> >The review was by Bob Kellogg, AF4IC. His e-mail address was listed
> >as "ae4ic@nr.infi.net". He stated that the loss was approximately 1
> >dB.
> >

> Wow, this is the ZM-2? 1 dB. I had no Idea 25% of the power was lost in
> these things. Seems a link coupled tuner should be .2 dB max in my book.

Ed and gang,

If you look up the original data, you will see that a loss of 20%=1dB or less applies
to a certain number of all the test loads measured. For the ZM-1 it
was 60 out of 144, but for the St. Louis Tuner it is only 1 out of 144
cases. I wonder WHY and what can be done about it?

For those who don't know: The St. Louis tuner is a CLC T network with
a tapped inductor on a iron powder toroid. Unused turns are shorted.
The caps are two section air dielectric. (There is also an SWR bridge
built in and it's in a nice and sturdy case.)

I can't recall a discussion of why the performance is so poor compared
to others in the light of these tests. I know, losses are unavoidable
and one dB is only one dB, but what could have been done better in the
case of the St. Louis tuner?

73,
Arjen Raateland
OH2ZAZ
--... ...-- -.. . --- .... ..--- --.. .- --..
Finnish Environment Institute, Helsinki, Finland
SAS Support
EMAIL: Arjen.Raateland@vyh.fi
tel. +358 9 4030 0457
fax +358 9 4030 0490
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