Paul P wrote:
Does anyone have a guess what value choke L112 found here
http://www.ppinyot.com/hammarlund.ht...Supply%20Choke
might be? I am getting a 190 ac volt drop across this puppy. It has a cold
DC resistance of 97 ohms. How I got there is also explained at the
hyperlink page above.

The short of it is, the negative bias voltages are down across all
associated tubes that share that supply. Google is no help.

Even a guess at this point would be nice. I have never calculated a choke
in this configuration before.

The choke has AC going through it, since it's on the input side of the
rectifier. My guess is that it's not just a normal choke but is a swinging
choke with a controlled saturation characteristic. It's acting as a
current regulator; as current rises the magnetic flux in the core rises
and at some point the core saturates and the impedance of the winding shoots
way up, reducing the current flow.

A 190V drop across it might be normal, or it might be a sign you are trying
to pull way too much current through the thing. What voltages do you measure
across C162 sections A and B? They should be fairly close to the maximum
capacitor ratings, I suspect. If they are within a reasonable range, I'd
say the swinging choke is fine, otherwise I'd suspect something is on the
secondary side is pulling too much current and it's hit the wall.

If it IS failed, Peter Dahl can probably rebuild it. You won't be able
to just drop in something off the shelf, and sadly design of saturable
reactors and magnetic controls and amplifiers is a lost art today.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."