The manual nulling was much faster and it didn't take long to get the knack of it!
No problem. I only remembered it because I have two 331A too repair and they are in the same family. The 333A/334A have the auto nulling, where the 331A/332A don't. I've used a 334A in production test, but I could get a manual null faster on a 331A. All four versions are nice Distortion analyzers.
On Wed, Apr 8, 2020 at 8:11 AM Chuck Harris <
cfharris@...> wrote:
I'm sorry Michael, I misremembered.? Before I looked in the
manual, I remembered lamps, of some sort, and CdS photoresistors,
and it registered as a choppers.
It is actually a Wien Bridge.? Three of the four legs are CdS
photoresistors.? One lamp feeds two of the photoresistors, and
the other feeds a single photoresistor.
The last time I worked on 334's was about 1984.? I am surprised that
I remembered as much as I do.
-Chuck Harris
Michael A. Terrell wrote:
> The 334 has an Automatic Nulling (A6 board) circuit which uses lamps and a
> single detector. I see no chopper.
>
> On Tue, Apr 7, 2020 at 12:04 PM Jeremy Nichols <jn6wfo@...> 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.
>>
>> Jeremy
>>
>> --
>> Jeremy Nichols
