Krohn-Hite manuals

[1audio]

Richard: reminder for you to check the hardware and schematic on your 4400/4402.

 

[31697B]

OK... 4402B:



The R, I believe, is between gate and drain is fixed. i added trimmer to it. Replaced other adjustable pots with multi-turn for fine tuning.

THx-RNMarsh

 

[31697B]

OK... 4402B:

View attachment 586907

The R, I believe, is between gate and drain is fixed. i added trimmer to it. Replaced other adjustable pots with multi-turn for fine tuning.

THx-RNMarsh

I didnt check against schematic.... dont know where I put the schematic.... may be thinking of 4400. But you can see where the variable r has been added in the 4402B. Looks like it is a 100K pot.

The IC that cannot be read is an AD633AN.


Hope this helps.



THx-RNMarsh

 

[1audio]

The AD633 is the analog multiplier. I'll send you a scan of the manual. There is no Jfet. I'll need to figure out where the trimmer is in the circuit. It may be a trim for the multiplier.

 

[31697B]

I did this at least 2 -3 years ago and reported it in the 339A upgrade section I believe... ultimately leading to new ultra low distortion osc/gen by others in new forum.
You should be able to find the part from your service manual. Meanwhile....

The data shown was directly from the osc output BNC on the front panel (<-125dB/1KHz)

However, for the Main ouput BNC ....

If you go thru the switched level and variable pot and another opamp distortion remained very low at 1KHz (THD = -120dB).

Using LT1468 in main output amps; 1v/100K --

10KHz (80KHz BW) THD+N = -100dB

10KHz THD = -116dB

For those using sound-card like analyzer products... this may be about as good as most of them.


THx-RNMarsh

 

[Waly]

Attached.

Mr. Marsh shows a modified KH4402B distortion performance that is 10 times better than the original spec. Not sure if the same would hold at all frequencies, given the rather simple schematic of the KH4402B I certainly doubt so.

 

[31697B]

The AD633 is the analog multiplier. I'll send you a scan of the manual. There is no Jfet. I'll need to figure out where the trimmer is in the circuit. It may be a trim for the multiplier.

It is R133 on the schematic you sent me for the 4402B. The R133 was made variable.


THx-RNMarsh

 

[31697B]

The data shown was directly from the osc output BNC on the front panel (<-125dB/1KHz)


THx-RNMarsh

found this in the archives labelled KH-4402B:





THx-RNMarsh

 

[Burnedfingers]

The people at Krohn-Hite are first rate. After looking for a service manual and schematic on the web and not finding anything I dropped them a line and they answered promptly and filled my needs for model 4100 info.

By today's standards there are some that would consider this piece to be less than equal to the task. It still has a place on my bench and despite its age still has low distortion, DC offset, and still is within a few hundredths of a volt in output. Its a great sign wave and square wave generator.

 

[gaetan8888]

Hello

I still have my Krohn-Hite 4200A, it's a very good piece of equipment.

Bye

Gaetan