[Amps] Transceiver Output Impedance

[Roger (K8RI)]

Saandy Eban wrote:
> .....this is definitely not so!
> The load impedance of the final transistors is defined by Ohm's law so that
> for a defined high power the load they expect to see can be a few ohms only.
> Here is where the output transformer comes into play: it transforms the low
> LOAD impedance the transistors expect to see to 50 Ohms at the amplifier's
> output.
>   
As the Pi or Pi-L network transforms the high plate impedance of a tube 
amp down to the 50 ohms.

73

Roger (K8RI)
> Think of the fact that immediately after the amplifier you have filters
> designed for 50 Ohms.
> You cannot expect good results from them if the do not operate in a 50 Ohms
> environment!
> Soooo, this thesis cannot be correct, simply because of physical reasons.
> 73 and all the best:
> Alex	4Z5KS
>
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Robert Carroll
> Sent: Sunday, March 09, 2008 2:10 AM
> To: amps at contesting.com
> Subject: [Amps] Transceiver Output Impedance
>
> I have been told that modern solid state HF transceivers have been designed
> to deliver rated power into a stated load resistance-almost always around 50
> ohms-but that their effective internal impedance looking into the output
> port while it is active and delivering rated power is nowhere near 50 ohms
> but rather closer to a few ohms if you can define such an impedance at all.
> Is this more or less accurate?  I ask in connection with the 87A input match
> problems Rit Nesbitt mentioned a few days back on this reflector.
>
>  
>
> 73
>
> Bob W2WG
>
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