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Author Topic: HV capacitor woes  (Read 1964 times)
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KI4THX
El' Guappo Ernesto
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It's 106 Miles To Chicago, We Got A Full Tank Of G


« on: September 08, 2017, 01:03:15 PM »

Hey guys, Im currently changing over a Henry 3K Classic (3cx1500) to a capacitor input power supply and have hit a snag. The current oil filled caps will be to small to use once I get rid of the choke filtered supply (16MF) and not meet the voltage requirement i will be putting on the tube (3500VAC X 1.4 =around 5200VDC unloaded). Where in blue blazes can someone find another oil cap to replace the old one ?

Any ideas or help is much appreciated !
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It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

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KF7WWW
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« Reply #1 on: September 08, 2017, 02:17:20 PM »

Contact W7TFO.. Probably has what you need..
Or I'll see what I have in the shed if he cant help you.
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KD6VXI
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Making AM GREAT Again!


« Reply #2 on: September 08, 2017, 08:27:35 PM »

Good God, that's gonna be a screaming amp for gain.  Better have a good parasitic suppressor in it.

Even the CB crowd limits the 8877 to 4.5 kv or so....

FWIW, I've run 6.4 kv unloaded on a 5 kv oil filled.  Sat on a Teflon sheet.

--Shane
KD6VXI
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KI4THX
El' Guappo Ernesto
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It's 106 Miles To Chicago, We Got A Full Tank Of G


« Reply #3 on: September 09, 2017, 11:52:56 AM »

I agree Shane, It will be running on (past actually) the ragged edge of the recommended voltage but I got a killer deal on a 1.5A CCS Hypersil from Dahl that I couldn't pass up. I did purchase a 0-280V @ 30A Powerstat to run it down...just a hair. Holy moly, the pictures of it didn't do it justice until it landed on my doorstep at 78lbs ! So much for mounting it in the original pedestal, going to have to put it in its own box with casters.

The original power supply in this particular Henry was a customer ordered special build, 5K power supply, the unit was actually built a two piece unit with a separate RF deck factory. Kind of neat, I've not seen another example like this anywhere. The voltage was already around 4800VDC unloaded, so a few extra hundred volts shouldn't make much difference (I hope).

Originally it had a 3cx1200 also, but I swapped that out with a 3CPX1500A7 last year. The CPX version should handle the slightly higher voltage it will be given.

Ive owned another Classic MKII X with the 8877 in the past, and at 4500-4600VDC legal limit tone was attained with about 40 watts drive. I actually had pretty good luck running a little DX-40 straight into it, Ha ha !

A couple days ago I added Gigavac HC-1 vacuum relays (four total- one for bias, one for input and a double set for output) and ordered a QSK sequencer board from harbauch (sp?) Electronics.

I really hate to string a ton of electrolytics around in the cabinet, but I might if I cant find what I need to give me proper C in an oil variant.



Any and all advice is welcome and appreciated !
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