Posted by RC Daniel [ 202.92.85.145 ] on May 22, 2008 at 05:16:08:

In Reply to: questions re 300b group build posted by duderduderini on November 01, 2007 at 08:36:06:

Hmmm, looking at your post, I am gussing you are referring to driving the 300B/s with a pentode *strapped as a triode* - the 1700Hy (grid)choke and Damir's previous threads seem to suggest. If that is indeed the case, disregard the pentode-related suggested below.

Yep, Lundahl can supply 'grid' chokes, as can Magnequest, SAC Thailand (SILK brand), and many other transformer suppliers.

As for driving 300Bs in parallel - quite a task; without doing the calcs, I think it would be pretty borderline... I think you would have some high-frequency roll-off at the operating points suggested, tho don't take my work for it. You could run a parallel driver stage, tho there are probably solutions that are easier to implement and less costly. I wonder what an E180F would sound like with a little more current (and lower plate resistance) - would stand a better chance of driving the parallel output...

Hope this helps in some small way.

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