Hey guys,
Been lurkin' here and have a few questions. I'm going to have someone build an Express clone for me. I'll be doing the hunting, gathering and some assembly. I want to be able to run both 6V6 and EL34's. Also will have external bias. I have the chassis (used Omar's source and am happy with it) and am going to get the parts from Hoffman and Mouser. I have been able to glean most of the parts info from the schematics/layout diagrams.
1. What type of switch (Mouser part#?) is used for bright switch? Should I
even install a bright switch?
2. External bias pot: Komet type looks very trick and I bet is pricey. Is
there a Mouser # on that or one that is similar. What other pot can
used?
Thanks in advance for any help.
Parts question
Moderators: pompeiisneaks, Colossal
Re: Parts question
Hi oggiedog!
The bright switch can be any of a whole bunch of miniature toggles available from Mouser. The Express/Liverpools used an SPDT switch with a center off position for this job. I've had good results with the 633-M201301, though you might also want to consider using a DPDT switch, not because you need the extra pole, but because it allows you to mount the caps (500pF and 100pF micas) directly on the back of the switch without a floating connection.
For the bias trim pot, the Komet uses a 50k ten-turn Clarostat (which Mouser don't carry), but you could use something very similar from Bourns, like the 652-3540S-1-503 which is in the catalog for $14.88. You'd also need to get the locking dial, which is similar to the 652-H-23-3A at $10.26.
Matt
The bright switch can be any of a whole bunch of miniature toggles available from Mouser. The Express/Liverpools used an SPDT switch with a center off position for this job. I've had good results with the 633-M201301, though you might also want to consider using a DPDT switch, not because you need the extra pole, but because it allows you to mount the caps (500pF and 100pF micas) directly on the back of the switch without a floating connection.
For the bias trim pot, the Komet uses a 50k ten-turn Clarostat (which Mouser don't carry), but you could use something very similar from Bourns, like the 652-3540S-1-503 which is in the catalog for $14.88. You'd also need to get the locking dial, which is similar to the 652-H-23-3A at $10.26.
Matt