[Bhmartin]

Roger & RM-9 Owners,

I have seen one or two RM-9 series amps in the resale market that have been converted by Roger to be switchable between triode and normal operation.  If memory serves me, these have had four added switches.  Makes sense as there are four PP tube pairs.  Question is that I would like to make this modification to my amp locally.  I assume that the mod is 4 switches, and maybe a reristor or some other component, being used to switch in and out a "strapping" of a couple of pins per tube pair.  Can anyone describe what Roger's modification consists of?

Thanks in advance.

[GMuffley]

If you can do without the switches, it is very easy to convert the amp to triode.  Just disconnect the ultralinear winding from the output transformer for each output tube.  Then, wire a resisitor, 220 ohm to 330 ohm (value is not critical) from the plate to the screen grid of each tube.  If my memory is correct, pin 3 is the plate on an EL-34 and pin four is the screen grid.