The Amp Garage

So, for the screen supply, that's three 1k resistors in total?
Thanks for the info - Pete.

According to the link, the GA-20 was made between 1950-1954. About 5,000 were made.
http://www.superiormusic.com/page199.htm

Check further down the page, GA-20 carried on till 1961, in 2 tone styling. Pete.

As you've found, fast blow fuses aren't suitable for high inrush current applications. 1/2 amp slow blow are available (long link as don't know what size fuseholder) http://uk.farnell.com/jsp/search/browse.jsp?N=500006+1001439+5446152&Ntk=gensearch_001&Ntt=500mA+fuse&Ntx=mode+matchallpartial&No=0&ge...

How are the screen supply resistors arranged on your JTM45? Like a regular plexi, 470 or 1k per screen grid, fed from the choke output node? Or like the Iss7 of the bluesbreaker RI, with a 1k from the choke output, then splits into 2 470ohm resistors to the screen grids http://www.marstran.com/1987T...

Have you got grid stoppers on the output tubes? Pete.