You guys aren't paying attention.
A transmitter with a 0 ohm output impedance doesn't imply that there is a
short circuit. We're talking about an effective source impedance, not a
termination impedance.
Furthermore, there's a difference between an amplifier being designed to
work *into* a 50 ohm load as compared to the amplifier *having* a 50 ohm
source impedance. As Al correctly said, if the amplifier has a true 50+j0
source impedance, and it is connected to a 50+j0 load, it is going to be
dissipating half of the power in the amplifier itself.
In reality, most modern solid state RF transistors we see on VHF/UHF have a
very low source Z (in the ballpark of 1 ohm). Stripline matching and other
techniques are used such that the device is properly matched when the far
end of the matching network is terminated in a 50 ohm load. Again, the
amplifier itself doesn't have a 50 ohm Z, it is designed to work into a 50
ohm load.
--- Jeff
> -----Original Message-----
> From: Wade Lake [mailto:[EMAIL PROTECTED]
> Sent: Tuesday, November 09, 2004 10:02 AM
> To: [email protected]
> Subject: Re: [Repeater-Builder] Re: Duplexer, etc.
>
>
>
> If your radio has an impedance of zero ohms, you'd better
> open the radio and
> look for the paper clip ;-)
>
> Its the same concept as an antenna tuner. it matches
> whatever impedance
> your antenna happens to present at the tuner to the feedline
> impedance.
>
>
> >
> > Actually, if the source impedance equals the load impedance
> then 1/2 the
> > power would be dissipated in the SOURCE ! Hope it doesn't
> work that way.
> > Ideally, the source impedance would be zero ohms.
> >
> > Cheers,
> > Al, K9SI
> >
> >
> > <snip>
> > > It's a fundamental "law" of RF engineering that maximum
> power transfer
> > > occurs
> > > when the source impedance equals the load impedance.
> > <snip>
> >
> >
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
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