>- The (your?) reported IMD difference between using a precision shunt
screen regulator and a zener-string regulatior was too vast to be true with
quality semiconductors.
Oh dear: the troll is active again.
Speaking as the person who some years ago spent a long time making such
measurements and trying to design tetrode screen-supply circuits which
combined good performance with good protection, I extensively documented my
findings in a number of published articles. My measurement results, and the
conditions under which they were made, have been available in print and on
the Web for a long time, and anyone is free (indeed encouraged) to repeat
the comparisons I made and confirm or deny them. The motive was
intellectual curiosity, certainly not pecuniary gain. Unlike Rich, I don't
produce and sell items for the amateur market.
I would think more of Rich's input to this reflector if it were backed up by
hard figures and measurement results. Hand-waving statements like the one
above don't cut it. And for Rich's information, the zeners used in my
testing came from a wide variety of sources (Farnell, RS Components, STC as
they were then) and were all premium full-price branded items -- mostly
Mullard/Philips. Some were even accompanied by a BS9000 release note. I
probably still have some of them if anyone wants to volunteer to measure and
test them and report back here.
73 John
GW4FRX
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