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Old 4th March 2012, 12:55 PM   #61
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I finally cracked it. Final layout!

one side:

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front view..

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what you see are the 2x 200mA chokes (anode voltage for driver section) and 1x 500mA for gu81m screen voltage.
2x 4700uf 385v caps for screen voltage.

The three 4 pin sockets are for 3 (per side) 866A type rectifiers.

interesting feature is a fan (8/12cm) which will be hidden behind the gu81m and will provide cooling around the gu81m, between the gu81m and driver tubes and cool the rectifiers all at the same time!

I am very happy with this layout and definitely think this is one of the final (if not the final) layout.

Any observations?

Thanks
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Old 5th March 2012, 01:51 PM   #62
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cold start for the tubes #300mA with 280v transformer. No arcs

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some flickering but it stop after 30secs.
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Old 5th March 2012, 03:38 PM   #63
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....and I laughed too soon. The 866A seems to be flaking. Here are some macros:

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it's not mercury...it loos like dandruff actually and is increasing with use of the tube.

Can someone confirm it is flaking?
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Old 5th March 2012, 09:01 PM   #64
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Possibly my last posts were unclear. The cold start was still preceded by warmup time (30 minutes). I simply meant the voltage was not ramped but switched on (simulating a system with heavy initial load and no softstart).

The flaking is not due to the current since at 280v the tube should be able to conduct almost 500mA of current.
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Old 6th March 2012, 05:29 PM   #65
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HV cap banks sandwiched between lexan

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Old 7th March 2012, 05:12 PM   #66
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HV bridge

2000v 3A
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Old 7th March 2012, 05:12 PM   #67
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sorry for the soldering I'll pass over the joints once I get my alligator clips locked in position to keep the frame from opening up.
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Old 7th March 2012, 07:34 PM   #68
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You might want to consider voltage equalizing resistors in parallel with those caps. The rectifier diodes too. Just good practice.

All good fortune,
Chris
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Old 7th March 2012, 09:17 PM   #69
nhuwar is offline nhuwar  United States
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This is a pretty cool build. I like it.
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Old 8th March 2012, 07:35 AM   #70
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I actually equalised the resistors with 2w 100k resistors just after posting the first photos...


what I don't know exactly is how to balance the diodes. 400k resistors in parallel?
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