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

Subject: Re: [Amps] Replacing padder caps on an Alpha 77DX / SX
From: Jim <>
Date: Sun, 24 Mar 2019 19:40:17 -0500
List-post: <>
If you think that adding a second tube double the plate load impedance....

then you don't understand how linear amplifiers work.

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 certaly increase.

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.

Jim W7RY

On 3/23/2019 1:58 PM, Jim Thomson wrote:
From: "Carl" <>
To: "Paul Christensen" <>, <>
Subject: Re: [Amps] Amps Digest, Vol 195, Issue 10--Replacing padder
caps on an Alpha 77DX/SX

<And also 2 holer AL-1500's which was as simple as using the AL-82 tube
<chassis and a filament transformer. W8JI pioneered that swap for his own use.

<Never had a report of any failures.


##  Very slick !   Is the oem PI net  retained ?   The resulting plate load Z  
a pair of 8877s  would only be one half of a single tube.   The 2 holer  would 
double the  tune and load C..and  one half the UH  on each band.

##  Was an out board  B+  supply used ?

Jim   VE7RF

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