Re: Tuner efficency

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From: Pastor-KC1DI (elbc@pivot.net)
Date: Thu Sep 06 2001 - 08:42:11 CDT


Thanks Bill ,
finally someone who speak with comon sense on the subject.
73 dave
----- Original Message -----
From: "Bill Coleman" <aa4lr@arrl.net>
To: "Low Power Amateur Radio Discussion" <qrp-l@Lehigh.EDU>
Sent: Thursday, September 06, 2001 8:11 AM
Subject: Re: Tuner efficency

> On 9/3/01 12:26 PM, Karl F. Larsen at k5di@zianet.com wrote:
>
> >Until you consider Q of the tuner elements it's hard to see how
> >there can be loss in a good L-C or C-L-C tuner. But after reading the
> >sections of the ARRL Handbook dealing with Q you learn (or re-learn) that
> >there are hidden resistances in the inductor that at HF frequencies cause
> >most of the loss. Capacitors have this hidden resistance too but they are
> >so small at HF frequencies you can ignore the very small effect.
>
> Tuner losses are usually inconsequential.
>
> If tuner losses were significant, then QRO operators would have
> considerable heat to disappate inside the tuner. A 1500 watt signal
> passing through a tuner with a 1 dB loss would have to disappate 150
> watts inside the tuner. If you've ever touched at 150 watt light bulb,
> you know that's a lot of heat.
>
> Feedline losses usually far outstrip tuner losses, even with open wire.
>
>
>
>
> Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
> Quote: "Not within a thousand years will man ever fly!"
> -- Wilbur Wright, 1901
>
>
>


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