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[Amps] Henry 2K-3 PS Mod

Subject: [Amps] Henry 2K-3 PS Mod
From: Kevin LaHaie <>
Date: Fri, 21 Mar 2008 11:37:34 -0800
List-post: <">>

I am planning to convert the stock P/S in my Henry 2K-3 to a purely 
capacitor filter primarily to increase the HV, but in addition some way 
that capacitor filters are better for SSB.   My other, newer Henry's (2K 
Classic X and 3K Classic X Mark II) still use the choke filter design, 
albeit with higher voltages, and never had a complaint!

My current plan, after reviewing the supply, would be to merely removing 
the choke, and the .1uf 7500v resonating capacitor across it, to provide 
a standard capacitor filter.  The stock capacitor is an oil filled 20uf 
unit rated at 5000v.  The stock bleeders are 3, 20k 100 watters in 
series across the output.

I am seeking 4 pieces of advice

1. What changes to the biasing is necessary with the higher plate voltage
2. Is there enough 'headroom' with the 5kv rated cap, or should I use a 
higher voltage rating.  Never a bad idea, but curious if it's too close 
to max HV.
3. Is 60kohms too little resistance for the bleeder in the capacitor 
filter design? I would like to 'cool down' the heat the amp makes at 
idle, and without the bleeders playing a big part in the regulation 
aspect of a choke filter, perhaps this value could be increased?
4. I have read that it's good practice to place a high value composition 
resistor across the wirewounds in case they open as a backup to bleed 
the cap.  What value would be recommended?

Thanks, any opinions?

73 Kevin K7ZS

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