If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #1500
Joined: Sat May 24 2008, 04:38PM
Location: Ojai, Ca.
Posts: 44
Hi all, I have been rat holing stuff for a quad 833C x4 for some time - lots of classic parts. I have some used tubes 833a's to get in the ball park before I buy new 833c's. I think it was Bert Hickman that told me about pinging the plates with a 10kv pulses to condition them for higher voltages. It may have been Jon Frue. Can anyone comment on this technique and how it works and is done? I would like to push 5KV or more. I have 4 tubes I am willing to beat up abit. Quadzilla is running higher currrent and lower voltage than I am thinking of pushing.
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
Wavetuner -
A process known as "debarnacling" or "spot-knocking" is performed during the manufacturing process of all large transmitting tubes. Basically, higher and higher voltages (but with controlled current) are applied across the tube's various internal elements until a spark occurs, which will always be initiated at near microscopic bumps, projections, or edges. The power-limited spark vaporizes the projection. As the "debarnacling" voltage is slowly increased, the big projections are vaporized first, and then smaller and smaller projections get eliminated. This process can substantially increase the ultimate breakdown voltage that a tube can withstand. Eimac recommends that this process be repeated in the field if the plate voltage exceeds 10kV.
It may also be useful at lower voltages if tubes are ever run at voltages above their maximum ratings. (Now what VTTC builder would ever do that??)
CAUTION: An adjustable DC power supply providing 0-65KV is required, along with suitable HV current limiting resistors, X-ray shielding, etc, etc is required.
The debarnacling process is described in an Eimac document titled "Conditioning of Large Radio-Frequency Power Tubes", which can be found at:
Additionally, all six chapters of the absolutely information-packed Eimac white paper "Care and Feeding of Power Grid Tubes" can be found at:
This is essential reading for anyone thinking about using large transmitting tubes for any purpose. This paper contains a stunning amount of information about the design, construction, theory of operation, use, and care of large transmitting tubes. It even shows the internal electron trajectories during tube operation!
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Pinging 833x to condition the plates for higher voltage
