Avery Fineman wrote:
. . .
Playing with bias on a transistor multiplier stage is fine for optimizing a
multiplication but all it is is play when there's nothing to compare one
bias setting with another as to power output at the desired multiple.
A spectrum analyzer isn't an absolute need, by the way, there's other
ways to measure the harmonic content. Is that in "Experimental
Methods..." published by the ARRL? [I'm pushing work-on-the-bench,
not books, pardon my attitude that has resulted from years of having
to produce hardware results, not paper reports]

Len Anderson
retired (from regular hours) electronic engineering person

Yes, that book is published by the ARRL. Its authors, Wes Hayward,
W7ZOI; Rick Campbell, KK7B; and Bob Larkin, W7PUA have, unlike so many
authors, spent careers doing just what you and I have had to do --
produce hardware results. Of them, I know Wes the best, having been
friends with him for about 30 years. After a stint at Boeing long ago,
Wes was a design engineer in the spectrum analyzer group at Tektronix
for a number of years, where his designs were incorporated in a number
of state-of-the-art spectrum analyzers. He went from there to TriQuint
semiconductor, where he designed many RF components which are in daily
use in probably millions of cell phones and other wireless products. He
recently retired and has been doing some consulting. His publications in
amateur journals, spanning decades, are legendary and many are seminal.
I don't know Rick quite as well, but he's also a very capable and
accomplished engineer (in spite, one might say, of his Ph.D. and period
in academia). For years now, he's also worked as a design engineer at
TriQuint. To get a feel for his approach to solving real problems, check
out the articles he's published over the years in QST on phasing type
direct conversion receivers. Bob I don't know at all, but Wes speaks
very highly of him, and I have absolute confidence in Wes' judgement of
skill.

There's nothing in that book that hasn't been built and tested, and
designed to be repeatable. And everything has been designed by people
who really know what they're doing. This isn't a book of
kluged-it-up-on-the-bench-and-made-one-work-once projects as so many
are. I'm sure that if you'd take a few minutes to look over the book,
you'd immediately recognize that.

To answer your specific question, I don't, in a brief scan, see details
in the book about optimizing the bias for maximum harmonic content of
the multipliers. Most are diode multipliers anyway, with no bias
adjustment. The book covers a very wide range of topics, and the section
on multipliers consists of only a couple of pages of text. There is,
however, a chapter on simple test equipment a homebrewer can build,
including a brief description of a practical spectrum analyzer. Wes did,
incidentally, design and publish such a thing some years ago. I think
it's still available in kit form from Kanga US.

I've also spent a career having to produce real results. But apparently
our approaches differed, because I've found that good paper designs,
often aided by fundamental knowledge gleaned from books, lead to good
hardware results, rather than being an opposing and somehow inferior
method. And they have the advantage of being well understood,
predictable, and repeatable.

Roy Lewallen, W7EL