And here I am with perpetual OT. Sorry, George. Just for quick confirmation, are you happy with your scope? BKSabath here would have chosen otherwise if time traveling was invented.
Hi Stajo,
the ringing is more obvious at lower frequency.
Do you have any ideas what to do? An RC somewhere maybe?
the ringing is more obvious at lower frequency.
Do you have any ideas what to do? An RC somewhere maybe?
I am happy with the scope, no problems. It does its gob. Also has a primitive signal generator, so you don' t have to buy one immediately. I saw what Sandro said, but I would not recommend a digital one as a first scope.
I have used old variable turn caps from old radios to track ringing frequencies in OPTs. It works. Usually that is on the GNF tho, which makes it a single cap parallell to the GNF resistor.
You won't get the real time waveform update, the low noise trace and the gradual shading that phosphor analog scope will give you from entry level DSO mind you.
You have to trace it first. Try a fat carbon on the grid is one thing to see if its your signal wire that goes antenna on some freq. For the OPT its usually not ringings in the low Hz area, they are much higher but they can interact on the lower frequencies.
Jones makes a Y split with caps to ground over the choke. Filter chokes almost always rings at some freq but thats not so bad as when the OPT (which is the last filter choke in a way) does it cause you have no more damping after there. You might try with parallell caps from 10 pF up to, I dont know,.. a couple of nF to see if you can see differences.
You are welcome any time, especially with nice hand-baggages!
I tried with carbon resistor, no change.
Regarding OPT, the LL1660 does have some nice ringing in the 50kHz region in my #26. After that, these chokes look nice!
I calculate that the freq of the ring is between 8333 hz or 10,000Hz. Assuming I read the picture right with 0.2mSec/div. I also think that if it were a signal riding on the output, it would not decay. Could be wrong though. A FFT would be interesting here.
The square on the picture is 1kHz.
The probe is 10x.
A FFT, good idea. Never done that, maybe should try and learn how to do it.
It' s getting cold tomorrow....
The probe is 10x.
A FFT, good idea. Never done that, maybe should try and learn how to do it.
It' s getting cold tomorrow....
Few kHz is very low to be some typical oscillation on the other hand. Puzzling. Could be those anode chokes have a characteristic resonance frequency?
That is what I was thinking. I feel it is a resonance based on the decay, but freq is pretty low. Also note that leading edge of square wave is pretty clean. Would be interesting to see what elimination of cathode bypass cap would bring on the 500Hz square wave