On Mon, 6 Sep 2004 06:20:23 -0500, "Richard Fry"
wrote:

How do I know? I was the author of all of the brochures and technical data
sheets for Harris' entire FM product line for the ten years before I
retired. That any published value of impedance applied to the load
impedance expected was/is universal across the product lines: AM/FM/TV.

Hi OM,

If you simply follow the reference trail of those trade publications
(the design guides used by the engineers who did the actual work) you
would find PLENTY of source Z discussion:

from Harris White Paper:
"High Linearity RF Amplifier Design"
referencing
"Advances in AM Modulation Techniques to Improve Digital
Transmission of HD Radio and DRM"

"The poor antenna match will create a significant ripple in the
transfer characteristic of the main power amplifier. If that
amplifier itself has a poor output match to 50 Ohms
[the succeeding discussion gets into the inability of feed
forward correction to accommodate to this condition and the
introduction of an expensive isolator and lowered efficiency]
.... Alternatively, the amplifier itself could be modified to
improve its output match."

From Harris White Paper:
"Improving Efficiency With Split-Level Combining"
referencing
"High-Linearity RF Amplifier Design" (op. cit.)
and
"RF Power Amplifiers for Wireless Communications"
ppg. 31-32, 110
Discussion of load pulling to determine the "source impedance."
pg. 99-103 , Figures 4.21 & 4.23
Discussion of the source transformation from source Z 4 Ohms to
load Z 50 Ohms. Amplifier exhibits an 78% efficiency.
and
"Feed Forward Linear Amplifiers"
"Frequency ripple is one of the principle factors that limit broad
band signal cancellation and hence feed forward performance."
....
"As previously discussed, to prevent loss of power due to
impedance mismatches the input and output impedance of a device
should be equal to the characteristic impedance (e.g. 50 Ohms)
of the source and load to which it is connected."

From Harris White Paper:
"REDUCING FM IBOC TRANSMISSION COSTS WITH THE PROPER
CONFIGURATION AND LINEARIZATION TECHNIQUES"
referencing
"Feed Forward Linear Amplifiers" (op. cit.)
and
"RF Power Amplifiers for Wireless Communications" (op. cit.)
and
So on and so on and so on (no deviance from commonplace
design considerations that have been described for generations).

73's
Richard Clark, KB7QHC