SOS Scout Hummmmmmmmm

[357]

Let me guess: new caps through-out.

I got a big hum and sounds like I got robot voice on my 99v enabled.

Problem #2.) 6ME6 tubes in final. Can this be right?

it also has 6jg6 drivers

Major big time hum on TX

EDIT:

I think I found the answer:

Q "I have heard that capacitors can go "bad", when and how can I tell if mine are "going" bad?"

A "Computer-Grade" electrolytic capacitors have an average service life of from 15-25 years dependent on the level of ambient heat they operate in. These caps fail in only two mode, "open" meaning loss of capacitance, or "short" meaning a dead short, usually resulting in an explosive destruction of the cap. A shorted cap would be pretty obvious, but if your caps are "open" how can you tell this? If the caps are open, there will be a marked drop in the plate voltage under a "no-load" condition. Also, when under load, the plate voltage will drop severely, and it is possible that an AC hum or severe distortion can be heard on the transmitted signal from this unit. If your amp is over 20 years old, it might be a good idea to buy a replacement set of capacitors for your amp. Always replace the full set of caps.

 

[357]

There are only 5 caps, whew!

 

[357]

Here are some pics.

Could i please get some feedback on the coil taps?
Can I shorten the coils for more efficiency?
Are they tapped correctly?

Also the "twin peaks" on tune/load.
What am I looking for and how do I get that sorted out?


Thank you!

Click on images for larger view

 

[Bionic Chicken]

It sounds like you have a tube with a grid short. That will produce what you describe. Check the tubes to make sure they don't have leakage.

Maybe a cap in the HV supply? Does it do this in low and high power? I have had tubes cause this problem many times before.

 

[357]

It does it on low and hi.
only getting 150w carrier with backwards swing.

I will have to hunt down a tube tester.

I think new caps won't hurt either.

:bdh:

 

[357]

Found a sweet deal on a whole sleeve of tubes!
Hope these will work.

Sleeve NOS 6LQ6/6JE6C GE Vacuum tube tubes Valve - eBay (item 260480392841 end time Sep-25-09 23:01:26 PDT)

 

[ethomas]

did that fix it?