Express noise problem

[ampdoc1]

Get one of those cans of air that they sell to dust off computers. Invert the can and the spray will be the propellant, which is very cold. If you spray it on a part that has a noise problem you can isolate that type of trouble very quickly.

ampdoc1

[PlinytheWelder]

FWIW, I used Allyn's grounding scheme as shown here:
(At least on the preamp...)

[img1250]http://verosurfcam.com/80W.jpg[/img]

A good read on grounding is here: http://www.aikenamps.com/StarGround.html

[billyz]

It looks like you grounded the buss wire to the standoff near the power supply caps. I always ground the preamp buss near to the input jack and it works well, my builds are very quiet. Also, a few of the pre tube leads are pretty long, shorten them as much as you can. It looks like your inductor is mounted in a different location than normal. I am sure it throws a magnetic field, might try moving it.

Otherwise it is a nice tidy build.

I use a 10k input grid resistor on the V1 to stop cell phones and RF.
Scratchy Presence pot is normal for this circuit.

[rooster]

PCollen - Hey, yes, you are on to it! There is also one from Merlin B that serves the purpose, however the Marshall adaptation is prolly more to the point. Good post.