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September 6th 03, 01:28 AM

On Fri, 5 Sep 2003 12:02:02 -0500 (CDT),
(Richard Harrison) wrote:

Richard Clark wrote:
"Motorola (in their confusion) offers:
For example, in the 180 Watt version the input transformer is of 16:1
impedance ratio, making the secondatry impedance 3.13 Ohm with a 50 Ohm
interface."

Does not seem confused to me.
16 x 3.13-ohm= 50 ohms by my calculation.

Hi Richard,

The expression of "confusion" is not original, nor embraced by myself.
It represents my wry comment, an irony in that this term (confusion)
applied to Motorola's specifications is rejected by data, experience,
Motorola (except through a particular reading of one application note
that seems to bear no relation to any known experience), and at least
three more vendors that I have supplied who all conform to this
practice.

Technical literature for RF Design Engineers is chock full of this
consideration that is taken for granted in academic texts (it would
only muddy the waters for students, I suppose). However, when
unmentioned, except in the footnotes, endnotes, or appendix (all
unread at hazard to speed readers) this academic shortfall gives the
impression that the topic is of no interest. Hence we read of
Motorola being confused about their specification of source Z that
everywhere in their literature is expressed with deliberation and
planning. To date, and through more than several inquiries to expand
upon this "confusion" I have been offered no data, other form of
specification, how it bears on application, or any correlation to
personal experience.

If you follow the thread back up several, you will find Tam struggling
to find negative confirmations, and through his lack of close reading
his "condemnatory" sources in fact supply me with all the engineering
details I had described as being part and parcel to a common RF
Finals' Deck.

73's
Richard Clark, KB7QHC

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