The old PT I was building around shorted through the HT secondary.
I haven't gotten it that bad in very long time. Lifted... my hip bumped a
grounded strip at the same time I brushed the chassis.... lifted good.
It was a very old paper and cloth former, watch out for those, could be your life
in the just the right circumstances. I'm very prudent about safety. still got it......
After isolating the problem I rebuilt the PS around a 25w deluxe replacement.
The bias tap (of which the other had none) was utilized for negative grid bias.
It appears to be go. I'll see tomorrow and post more complete scheme and pictures.
The main point of such a rig is to get data and graphically generate the
plate and grid families of static characteristic curves, and plot a dynamic transfer curve.
As well as finding transconductance, amplification factor and plate resistance
bench matching rig?
Moderators: pompeiisneaks, Colossal
-
Andy Le Blanc
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: bench matching rig?
lazymaryamps
-
Andy Le Blanc
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: bench matching rig?
Pictures.....
The test socket is indispensable, any body know right off hand where to get more?
It works, Its perfect for you to go by the book and replicate lab procedures
to demonstrate the tubes characteristics, as well as tube matching.
I don't mind going the distance with the math, it makes one self sufficient.
Why spend the $$$ on a product, or sit at home playing with your software.
I still have questions about it of course, but the repairs have backed up
behind the project and need attention.
The test socket is indispensable, any body know right off hand where to get more?
It works, Its perfect for you to go by the book and replicate lab procedures
to demonstrate the tubes characteristics, as well as tube matching.
I don't mind going the distance with the math, it makes one self sufficient.
Why spend the $$$ on a product, or sit at home playing with your software.
I still have questions about it of course, but the repairs have backed up
behind the project and need attention.
lazymaryamps
-
Andy Le Blanc
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: bench matching rig?
this really is all it is....
The 12au7 acts as a constant current source, replacing a taped transformer,
and adjusted with a 10k pot. I like to get a 3 turn or a 10 turn precision.
I uses fender replacement as a PT, the bias tap and a typical bias supply works well here.
again a precision pot. would be nice.
The heaters for the valve under test use a separate 12v PT and a 50 ohm
rheostat in series is used to adjust the ac.. The 12au7 uses the 6v supply
from the larger 25w deluxe tranny.
I'll need a tube with a known transconductance soon to compare procedure
with and see if using a CCS interferes with the results
The 12au7 acts as a constant current source, replacing a taped transformer,
and adjusted with a 10k pot. I like to get a 3 turn or a 10 turn precision.
I uses fender replacement as a PT, the bias tap and a typical bias supply works well here.
again a precision pot. would be nice.
The heaters for the valve under test use a separate 12v PT and a 50 ohm
rheostat in series is used to adjust the ac.. The 12au7 uses the 6v supply
from the larger 25w deluxe tranny.
I'll need a tube with a known transconductance soon to compare procedure
with and see if using a CCS interferes with the results
lazymaryamps