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previous: Ken Gilbert q{Re. does adding a cap bypass to t... -- 3/1/2000 10:05 PM View Thread

Re: bypassing rk's and effects on thd

3/3/2000 5:04 PM
dpcoyle
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Re: bypassing rk's and effects on thd
I'm glad to have found Amp Page.  
 
Ken, not only was I wrong to think cathode bypassing was all good, I made another error yesterday asserting that a common cathode stage wants a limited current source. Diff amps and cath followers do, but comm. cath wants fixed voltage, not fixed current.  
 
Your reference to p327 of RDH is about how magneticaly coupled devices subjected to current feed back preferentialy eat the high frequencies because they change fast. This allows only the lower frequencies through, leading to sinewave output. P327 doesn't describe resistor loaded problems.  
 
P554 says there is distortion if the bias tracks the grid voltage, as it does for unbypassed Rk's. Yes it's swamped, but understanding that it's going on is intersting if you want a complete understanding of how the tube works.  
 
thanks for setting me straight.  
Dan