While speaking with a customer service rep at RF Parts about tubes for this amp, he suggested that I check the resistors in the parasitic suppression network before ordering. Turns out that my board doesn't match what is shown on the schematic that came with the amp. There are capacitors on each side of the resistors that are in series with the resistor and they aren't shown on the schematic that came with my amp. Turns out that all the resistors values range from 99.5 to 100.5 ohms. Anyway, I found a schematic of an early version of the amp that shows the "additional" capacitors (http://www.w8ji.com/al811h_schematic.htm
). I'm wondering if I should remove those "additional" capacitors and install a strap in their place. I'm referring to the circuits RFC-15 thru RFC-18 (aka PC-15 to PC-18). Also, the early schematic shows 2 relays but my amp only has one. There may be other changes that I haven't found yet. The schematic that came with my amp looks more like the schematic found at http://www.ameritron.com/support.php?productid=AL-811H
. Look at the plate circuits of the 2 schematics and you'll see the difference.
I guess this amp has gone through several modifications over the years. But, I'm wondering why I didn't get an accurate schematic with my amp.