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

[Jim]

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.

73
Jim W7RY


On 3/23/2019 1:58 PM, Jim Thomson wrote:
> From: "Carl" <km1h at jeremy.qozzy.com>
> To: "Paul Christensen" <w9ac at arrl.net>, <amps at contesting.com>
> 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.
>
> <Carl
>
> ##  Very slick !   Is the oem PI net  retained ?   The resulting plate load Z  with
> a pair of 8877s  would only be one half of a single tube.   The 2 holer  would require
> 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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