HV bridge rectifier design considerations

[N3DRB The Derb]

Having fixed a bunch of the other problems in Jenny Gonset the Amplifier, I am pulling the bridge rectifier board today and getting to work on that.

This is necessary because the original design had neither the current handling capability or the PIV rating to run the 4 811's with a double margin of safety, much less the 4 572 B's I'll be running. There was a factory bulletin put out in 69 that details additional diodes to be placed in the stack, going from 12 to 24 per leg, each original diode having a 47K resistor across it. They want you to cut all the resistors out, after putting in the new diodes. Why is this?

The old diodes are rated at 600 PIV@ 500 ma each. Teh new diodes will be 1N4007's as of now. These have a rating 1000PIV@1000ma each. Most bridge circuits I have seen have resistors and in some cases a disk cap across each diode, but not all.

Someone take me to school on this schiznit. What's desirable, what's not, etc.  I'm taking everything off and starting from scratch and building out.

if you have a better suggestion as to what diode to use for the stack, I'm all ears.


 

[WD8BIL]

Hey Derb,

All my stacks have been 6 per leg 1n5408 diodes. 3 amp 1000 PIV. That's what we used at that now de-funked amplifier manufacturer. Worked primo Munky Man.

Those 572Bs can hog some current. I'd go with the 3 ampers for headroom dontchaknow!

[w3jn]

Got yer parts boxed and will send 'em today, DRB

[N3DRB The Derb]

h-ok John. The amp is starting to look pretty sweet. I used the stupid glue on the cracked ceramic with the finest chinese made runny shit you can buy. Worked FB OM.

The amp project has turned the corner. There is now more stuff repaired than there is broken or needing changed due to ravages of time. This thing will be very dependable. I also might get around to putting in the RGS-400 coax input and outputs today. The silver plated connectors had massive amounts of tarnish and pitting due to sitting up against steel for 40 years. The so-239 "out" jack was literally glued to the chassis by black crudstuff so thick I had to Dremel it off after the nut and lockwasher wuz removed. Tarn-X couldn't touch it. The T/R switch is repaired and back in. The new 3 wire ac line cord and fuse holder are in.

Money is tight right now so I am fixing everything else in the beast before I go back to the bandswitch. I want to silver plate the tank circuit and switch before I put it back in, and I'm gonna use one of those plug and plate systems from http://www.caswellplating.com/kits/plugnplate.htm and do it myself. I dont have to, but for a 40 buck investment I need never worry about such things again and I can repair other gear with it as needed.

 

[WA1GFZ]

Derb,
Silver oxide is a better conductor then pure silver.

[N3DRB The Derb]

yeah I nose that but it's ugly as shit.    Whereas silver is kewl and beautiful. 

[WA1GFZ]

hey Derb what about your friends we are pretty ugly....you gonna plate us

[flintstone mop]

Hey TIM, whats going on here??? Did I miss something in this magical thing called radio???
YOU have replaced the 811A's in your Jenny Gonset with 572B's. I have an Ameritron that has 3 ea AL-811 pubes. Can I do the same ? OR is there a penalty for this mod?More JUICE??

Phred

[N3DRB The Derb]

Mostly can yer suckply and tank circuit handle the increased current and input power? You'll have to disconnect the bias too - 572B's are 0 bias to 2500 volts.

4 572 b's have 10 times the plate dissipation of 4 811A's. Each tube has 2.5X a 811A. They need a lot of current. if that ameritron has a cap input supply,
you may have to increase the filter a bit to get decent regulation. It's going to be a current issue on the suckply and can the tank circuit handle the juice?