TopBand: MLA2500

[Joe Subich]

In <961118225227_351477338@emout11.mail.aol.com>, on 11/18/96 
   at 10:52 PM, W8JITom@aol.com said:

>The MLA does NOT need more Q, once Q is larger than one plus the sqrt of
>Rplate/RLoad any further increase in Q lowers the efficiency. The MLA
>already has more Q than necessary.

Tom, 

Is a Q of 8 enough to provide sufficient harmonic rejection/TVI
supression, etc?  All of the "how to build a linear" articles I've seen
over the past 40 years of the magazines (I had a fair size collection
before I moved the last time) talk about a minimum Q of 10 and preferably
12.  Even with the "high impedence" tubes, 1 + (Rplate/Rload)^.5 gives a Q
of less than 9 at amateur power levels. 

Of course, keeping the Q down to 10 is a real trick at 10 meters with the
output (plate to grid) capacitance of most tubes.  The MLA is a real
problem with it's 75pF minimum in the tuning cap!

-- 

73, 
   ... Joe Subich, AD8I
       <AD8I@ibm.net>
       <subich@ibm.net>


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