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Author Topic: old Henry 2K PS upgrade  (Read 732 times)
KU7I
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Posts: 122




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« on: March 23, 2010, 05:01:43 AM »

I have noticed that the older amps that use a choke input filter network such as the old Henry amps use a small value for the filter capacitor. My old Henry 2K used something like a 10uf oil filled cap after the resonant filter choke network. Is their a particular reason to not use a 32uf 4500v GE unit that I have a couple of as a replacement?

 

Second question, since I have two of these GE units would I see any improvement or increase in B+ if a placed one of these units before the choke network? The new configuration would be cap –choke – cap, or 32uf cap – choke – 32 uf cap.
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AD4U
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Posts: 2153




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« Reply #1 on: March 23, 2010, 10:22:21 AM »

I am not familiar with your Henry amp, but (in my humble opinion) a resonant choke HVPS is the best there is.  Regulation from no load to full load is outstanding.

But then some will argue that good HV regulation is really not necessary in a typical HAM linear amp.

If you change the PS to a capacitor input configuration, you can expect the HV to increase considerably, on the order of 30% to 40%.  You need to be sure other components in the PS and amp can stand the increased HV.

Dick  AD4U
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KU7I
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« Reply #2 on: March 23, 2010, 03:08:08 PM »

Thanks Dick, noted. Lane ku7i
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W8JI
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« Reply #3 on: March 23, 2010, 05:21:29 PM »

I have noticed that the older amps that use a choke input filter network such as the old Henry amps use a small value for the filter capacitor. My old Henry 2K used something like a 10uf oil filled cap after the resonant filter choke network. Is their a particular reason to not use a 32uf 4500v GE unit that I have a couple of as a replacement?

 

Second question, since I have two of these GE units would I see any improvement or increase in B+ if a placed one of these units before the choke network? The new configuration would be cap –choke – cap, or 32uf cap – choke – 32 uf cap.

You have to be careful messing with resonant filters. The only time I was nearly killed by shock or burn was with a resonant choke supply. If you get something wrong, like the choke on the wrong side of resonance, voltage or current can go astronomical.

Choke supplies also can have series resonances with the choke and filter capacitor. You'll probably be safe adding capacitance to the output, but it may not do anything good.

The voltage output of a choke input supply on sine wave power, ignoring losses and assuming more than critical current, is .9 times transformer RMS. The voltage output of a capacitor input supply is 1.414 times transformer RMS. .9 to 1.414 is a 1.57 change. The no-load voltage will be about 1.57 times the original voltage. If the original choke input supply is 3000 volts dc, it will go up to around 4700 volts with a capacitor input. Very few systems would take that abuse.

73 Tom
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KU7I
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« Reply #4 on: March 23, 2010, 09:03:09 PM »

Tom,
Noted, thanks again!! PS really like your website.

Lane
Ku7i
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