Finally got it working...
I guess the tube is a little on the dead side, with the proper bias (-16V) after I fixed the voltage divider circuit, amp was more of a power absorber than an amplifier.
Finally gave up and changed the bias to -36VDC on TX and RX, and amp works fine. Apply a little carrier to it, and background noise, hashy sound etc all goes away. When the tube is cold, amp only does about 40-60 watts, LOL, but once I talk on it a while it heads up to about 100-125 watts. It was a used tube from a JB200 and I have no idea what it has already been through.
Pulled the other tube out of the JB200, it made a spark when turned the amp on, a little blue spark inside, then as I talked on it a little it made more sparks in there, and I took it out. The output seemed good from the tube, but there are some little flakes (like a grey color) inside the tube, not sure what those are, look like ash or something, I was wondering could those have been causing the sparking? Should I toss the tube or will it eventually quit the sparking inside?
Wondering if I had a "new" tube in the amp, with the bias set back to -16VDC would it actually work? How much power is a JB150 supposed to put out with a good tube anyway?
What is it about converting to a EL34B tube? Are they that much cheaper than an NOS 8417? I seen them from $10-$100 for EL34B's. Some of them were some special Tug-Sol tube with higher than normal impedance. What's that all about? Is it just a drop in replacement, or are there some other changes to run the EL34B in place of the 8417?
Being a tube amp noob sucks, but learning a little as I go, when I get time with read up a little in the textbooks. I have a couple old tube amplifiers that I am going to scrap for parts and build a decent unit out of to use on my base. They have already been hacked up and are multi-colored and what not already so I figure what I have got to lose, the stuff is paid for, and some of it works, some of it don't.... Been fun playing with the Blackcat, amazed at how simple it is....
