John,
Yesterday I built the supply we were discussing a few days ago - 12.6V@4A into 25V 10A bridge rectifier, into 1,000uF cap, into the 7805 (TO3 package), into a .1uF cap.
Works brilliantly - 5.02V under 750mA load, and no ripple.
So, thanks for the help!
Now I just have to figure out where I picked up a 60Hz hum from!
I "cleaned house" a bit in the chassis - moved some leads, shortened others, and now I have a bit of hum that gets louder as the gain is turned up. It's not the new filament supply, because I still have it when I switch to a battery on the filaments.
If I ground the grid of the first 01-A, the amp is totally quiet, even with the volume up full. So, that tells me the 2nd stage, and the ouput stage are not the cause... 
Yesterday I built the supply we were discussing a few days ago - 12.6V@4A into 25V 10A bridge rectifier, into 1,000uF cap, into the 7805 (TO3 package), into a .1uF cap.
Works brilliantly - 5.02V under 750mA load, and no ripple.
So, thanks for the help!
Now I just have to figure out where I picked up a 60Hz hum from!
I "cleaned house" a bit in the chassis - moved some leads, shortened others, and now I have a bit of hum that gets louder as the gain is turned up. It's not the new filament supply, because I still have it when I switch to a battery on the filaments.
If I ground the grid of the first 01-A, the amp is totally quiet, even with the volume up full. So, that tells me the 2nd stage, and the ouput stage are not the cause...
hum
If it varies with the volume control it obviously comes in with the signal, so it either is already on the output of the source or preamp, or it rides in on the connecting cable. (Assuming your vol control is up-front in the amp). If you use another source/preamp, is it gone? If yes, you have isolated the problem. If not, check the grounding and ground routing of your signal input connector and/or the cable.
Jan Didden
If it varies with the volume control it obviously comes in with the signal, so it either is already on the output of the source or preamp, or it rides in on the connecting cable. (Assuming your vol control is up-front in the amp). If you use another source/preamp, is it gone? If yes, you have isolated the problem. If not, check the grounding and ground routing of your signal input connector and/or the cable.
Jan Didden
dhaen said:I'm sure a man of your calibre, won't need our help in finding a small hum problem
Indeed.
I did find it.I'll give you a hint - a .1uF cap followed by a 150Hy coil to ground makes a great receiver for "broadcasts" in the 60Hz range...
You see how even I can get carried away with the iron!?
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