On 4/7/20 12:04 PM, Jeremy Nichols wrote:
Purely out of curiosity, what is the purpose of a chopper in a 334
distortion analyzer? HP used choppers in a lot of their DC voltmeters to
convert the DC to AC. They¡¯d run the AC through some amplifiers and then
convert back to DC to run the meter. That took care of the old DC
amplifier drift problems. Since a distortion analyzer is already working
with AC, I would think a chopper wouldn¡¯t be necessary. Obviously
there¡¯s something I¡¯m missing.?
Unless my memory is failing, it's not strictly a chopper, but it's
part of the automatic tuning system. The choppers are
digitally-controlled switches, but I believe the LDR-based subsystem in
the 33x distortion analyzers are more "analog" in nature, to follow the
fundamental frequency automatically.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
Dave McGuire