[Amps] Re: hi C out

[zl1aih at ihug.co.nz]

Hi Mike,
Yes, I still have the HR with W4MB's article and your memory is 
correct.   It's a 'must read' for newbie amp home-brewers with 
limited budgets.   However, it should be read in conjunction with 
Rich Measures' info concerning parasitics, especially when you 
are using a bread-slicer for C1 in a Pi or Pi-L tank circuit - I had 
some problems with a pair of 4-400s in GG until taming the 
parasitics with Rich's measures (no pun, I assure you) - until I 
lengthened the anode leads to C1, I couldn't get resonance on 10 
metres.    Afterwards, the amp was unstable until I installed the 
nichrome supressors - totally stable from 80 to 10.
73, Ken ZL1AIH
    
I seem to remember an article in Ham Radio from the 80's regarding an amp.
using three 813s built by Bob, W4MB, where he did the calculation for the
inductance that went from the plates to the blocking capacitor.  He was
interested in reducing the affect of the plate capacitance so he could
tune 10 meters.  As best I remember he was converting the parallel
capacitance to an equivalent series capacitance and then inserting an
equal inductive reactance at 30 MHz to compensate for the series
capacitance.

Anybody remember the article?