[Amps] step start

[Alek Petkovic]

If you want a great soft start, just go to Ebay and search for


  100A 4000W High-Power Soft Start Circuit

I bought 10 of them and have used them in 3 projects so far. They are 
very quiet and all self contained on the one small board.

I'm pretty sure they do a 120V model as well.

I'll be using another one in my AL-1500 when I fit the W7RY QSK in the 
cominging weeks.

73, Alek VK6APK

On 3/10/2023 2:21 am, Val wrote:
> Hello Paul,
>
> As you will put the step start circuit in the transformer primary, it 
> will limit the transformer inrush current and thus all the voltages 
> provided by the transformer - filament, screen, grid, plate.
>
> 73, Val LZ1VB
>
>
> На 01-10-23 в 21:19, Paul Decker написа:
>> Hello all.
>>
>> I'm building a 4cx1500b amplifier. This is the first tetrode high 
>> power amplifier I've tried to do.  I'm using about 300V on the screen 
>> and 2500 on the plate.
>>
>> For my power supply I'm using a 1 Henry choke input on the screen 
>> supply dumping into 200uF This seems pretty stiff.  For the plate 
>> supply it's a voltage doubler outputting 2700 V dumping into 93uF.  
>> Not quite as stiff, about 300V drop under full load. I have plenty of 
>> capacitors, so I can add more capacitance if needed.
>>
>> Two questions,
>> 1. is the plate voltage regulated enough or do I need more plate 
>> regulation and
>> 2. for soft start,  Should the soft start bring both the screen 
>> voltage and plate voltage up or should I let the screen voltage be 
>> and just soft start the plate voltage.
>>
>> Thanks for any insights you all might have.
>>
>> Paul
>> KG7HF
>>
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