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[Amps] Replacing padder caps on an Alpha 77DX / SX

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Subject: [Amps] Replacing padder caps on an Alpha 77DX / SX
From: "Jim Thomson" <>
Date: Mon, 25 Mar 2019 09:24:02 -0700
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Date: Sun, 24 Mar 2019 19:40:17 -0500
From: Jim <>
Subject: Re: [Amps] Replacing padder caps on an Alpha 77DX / SX

<If you think that adding a second tube double the plate load impedance....

<then you don't understand how linear amplifiers work.

##  Re  read my post again.  Suck more plate current,  plate load Z  DECREASES.

<Now if you double the plate current, (1.8 amps, which a stock AL1500 
wont do) then the plate load is half.

<But the best you could hope for is 1.1 amps or perhaps a little bit 
higher on CW or SSB... Then it would certainly increase.

##  nope,  plate load  Z will decrease.   Plate load  Z is  just 
loaded  B+    divided  by.....  1.7  X  plate current. 

<Last time I checked, plate load is a function of plate voltage and plate 
current. Nothing more... Nothing less.

Good luck getting 3600 to 4000 watts output from an AL1500.

##  Its already been done  several times. ..old news.

##  Been done  using a AL-1500  chassis..and also an AL-82 chassis, but a bunch
of stuff has to be changed and also modified.     Everything from blower,  fil 
entire  B+  supply,  tank circuit  tuned input, bifilars, entire tank 

##  I would not waste the effort on that mod...although its doable.   Its  a 
lot of effort for
not much improvement.    A single  3CX-3000A7 is  a lot more cost effective, 
dead simple   GG  triode.
8.5  kw out, ccs  cxr,  24/7 .   With a typ 200w  xcvr,  its typ  5.6 kw pep or 
cxr out. 

Jim   VE7RF
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