Arny Krueger wrote:

THD as speced by the manufacturer is not the only measure of equipment
quality. For example, a lot of the HP equipment would meet spec near
their end of life or the end of life of their tubes. while Heathkit
equipment might meet spec only if routinely maintained.

HP's audio signal generators were renouned for their relatively high
power output, on the order of 1 watt for some models.

When you look at THD specs, you have to consider the whole operational
environment, including the power level, the impedance of the rated
load, and the frequency range.


I had a version that used a pair of 6V6's for about 20 watts output.
It was built to test telephone lines and carrier current loops. Add the
right transformer to the output, and it made a great 120 VAC variable
frequency power supply. I had some of those large 24 VAC school clocks
and used one with the carrier loop generator to vary the speed f the
clock. Would would tell a pesky salesman he could have 15 minutes, then
I would turn up the frequency to only give him four or five minutes,
then slow it down and tell him his time was up, then point to the clock
over his head. They never caught on. ;-)

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

As an aside Jim Williams of Linear Technology has written very
intelligent pieces on HP Wien-bridge oscillators and building an
improved solid state version. I doubt it is on the web but you may be
better at finding it than me.

"Bret Ludwig" wrote in message
oups.com...
As an aside Jim Williams of Linear Technology has written very
intelligent pieces on HP Wien-bridge oscillators and building an
improved solid state version. I doubt it is on the web but you may be
better at finding it than me.

I have it, actually. It's in a book published by Newnes, isn't it?

"Bret Ludwig" wrote in message
oups.com

As an aside Jim Williams of Linear Technology has written
very intelligent pieces on HP Wien-bridge oscillators and
building an improved solid state version. I doubt it is
on the web but you may be better at finding it than me.

The name of the article is:

"Max Wien, Mr. Hewlett and a Rainy Sunday Afternoon", included in the book
"Analog Circuit Design: Art, Science and Personalities" . See Amazon, etc.