ghost noting

[Jay D]

Hello RG:
I have an inductance bridge, and tested the choke which is a little over 4 Henries, with a DC resistance of 100 Ohms. The choke tests good, and I have had an experience with repairing a Traynor head amp that had ghost notes - and found the choke shorted out.
This is a very good trouble shooting tip as for some people forget about chokes and what the original intent that they are used for.

Thank You,

Jay D.

[R.G.]

Hello RG:
I have an inductance bridge, and tested the choke which is a little over 4 Henries, with a DC resistance of 100 Ohms. The choke tests good, and I have had an experience with repairing a Traynor head amp that had ghost notes - and found the choke shorted out.
This is a very good trouble shooting tip as for some people forget about chokes and what the original intent that they are used for.

Ah, well. I missed another one.

Yeah, people forget the choke is there. I had a choke that was soft-shorted to the choke core once. Had a devil of a time finding that one, as it was high enough resistance that it didn't show as a short on the units-ohms range of my meter. But it sure did load down B+! That's another hard one to find.

I wonder - If you scoped the plates of the output tubes, would you see the ghost note showing up there?

Hmm... if you bridge the first filter cap with a BFC (big freakin capacitor) does the ghosting change?

Can you feed in a high frequency and see the ghost as an envelope ripple on the output signal?

Is it possible that you're getting magnetic pickup of hum in the OT modulating the signal? Did you change the relative orientations of the PT, choke, or OT?

[Prairie Dawg]

Ah, well. I missed another one.

Yeah, people forget the choke is there. I had a choke that was soft-shorted to the choke core once. Had a devil of a time finding that one, as it was high enough resistance that it didn't show as a short on the units-ohms range of my meter. But it sure did load down B+! That's another hard one to find.

I wonder - If you scoped the plates of the output tubes, would you see the ghost note showing up there?

Hmm... if you bridge the first filter cap with a BFC (big freakin capacitor) does the ghosting change?

Can you feed in a high frequency and see the ghost as an envelope ripple on the output signal?

Is it possible that you're getting magnetic pickup of hum in the OT modulating the signal? Did you change the relative orientations of the PT, choke, or OT?

RG, do you think that in such cases as you describe an insulation tester or megger might have some utility? I've got an IRT2 that I picked up at a yard sale for five bucks and it's been a blessing having it when evaluating iron in my stash that I'm thinking about using in a build.

[cthulhu]

ghost noting

You can check all of the above and still have ghost noting. One thing I haven't seen mentioned is ground loops. Grounding is such an art. I've star grounded amps and introduced ghost noting, only grounding back to near stock configuration fixed it.

[Jay D]

Ghosting Notes

Hello:
Thank You!
It was a grounding issue.

Jay D