[Boatanchors] Mercury Vapor Rectifier Lore Needed

Garey Barrell k4oah at mindspring.com
Fri Oct 11 16:05:24 EDT 2013

Hi Wilson -

The big search didn't come off this month.  They're promising next month for sure!

I ran mercury vapor 816's and 866A's in my Globe King for years.  Never a failure.  If they haven't been stored base 
down, they should be run with filament only for at least 30 minutes before applying HV.  The silver streaks you're 
seeing on the glass is unvaporized mercury, and that's a bad thing. This is the stuff that gets on the insulators and 
between elements making for large bangs.  It should ALL be gone when they've been 'cooked' long enough.  It's also best 
to give them at least 5 minutes warmup before each use, as long as they aren't disturbed.

I've heard bad things about superglue as a base cement.  There are a LOT of thoughts around, the closest to the original 
is the black stuff used for sealing furnace ducting.  Some use epoxy, but I can't think that would be good either.

The simple answer is the 3B28.  It works in any position and needs no warmup.  Unfortunately, no blue glow!!  I kept a 
set of 3B28's to use on my Johnson Valiant when I had to operate it on it's side, but put back the 866s when it was 
ready to go back on the desk!!

I'll let you know on the SS.

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs

Wilson wrote:
> I’ve been resurrecting some gear with 866s in it, and Wonder about some of the things I’m seeing.
> I’ve used 866s all my life, but never thought much about them, except good or bad.
> Some have much more glow than others, and the more glow the whiter.   Is this because of air getting in?
> Some have what looks like shards of metallic stuff on the glass.  Is this a coating off the plate?
> Last night, I had one that glowed pretty white, but also had a neat ring of fire dancing around the anode, with fingers pointing outward.  What was going on there?
> Sometimes one will are over inside and blow fuses, etc.  How can that happen, if the plate and filament are not out of position?
> I recently had a big flash from the back of the rack, accompanied by a colossal bang, as loud as a .22 LR shot!
> I looked all over the PS for evidence of arcing, but didn’t find any.  Later, I took hold of the 866 to take it out and the whole bulb came off in my hand!
> It broke perfectly cleanly, right around where it went into the base.  This has now happened twice and I’ve never seen it before.
> Both these tubes were loose in their bases, so I shot in some superglue to hold them.
> Could it be that the superglue bound them so tightly to the bases that they couldn’t expand and broke from stress concentration?
> Or could it have been that the superglue caused a thermal stress concentration in the class.
> Anyone ever see one break this way?
> Wilson
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