[AMPS] Tuned Input Circuit Q

[2]

>
>> For me, changing the tuned inputs from 52-ohms out to 26-ohms out is
>> preferable,  Decrease L1, increase Cout, make Xc-in=20 - 25 ohms (Q=2.5 -
>> 2.0).  Tweak for best match.  However, a second 8877 is only going to
>> make c. a 2db difference at the Rx end, so it's a questionable
>> expendature -- especially in view of extant tank problems when the second
>> 8877 is added.
>
>My comments were related directly to Alpha amps, Rich.
>Alpha did not use pi network input circuits in the 77 series amps.
>To prevent drilling many holes and adding expense, the "two-tube"
>kits furnished an un-un instead. No tweaking was required if the input
>L/C was correctly tuned to begin with.
>
//  Eimac recommends a low-pass Pi tuned input.  

>I will not get into the pros and cons of how loud or not loud the
>2nd 8877 makes you. 

//   A wise choice, Phil.  The guys on AMPS who spent kilobucks on c. 
+2db imagine it made them the king of the pileup world and they bristle 
like porcupines at any suggestion that 1/3 of an S-unit is insignificant 
with normal QSB.  

> This "kit"  was a way around the FCC regs
>that were in place at the time. Money is the motivation for converting
>a 77DX to an SX. A profit of $1500-$2000 was not uncommon for those
>in the "kit" installation business in the 80's.
>
//   Whew.  The original 1980 Plywood Box amplifier cost c. $1300 in 
parts.  

cheers, Phil

-  R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.  
end


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