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 #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Well, this tube is officially ruined. The filament has been acting weird, when i turned it on with the current limiting resistors for a slow start up. But now, every time i bypass the resistors, one quarter of the filament glows very brightly. It is about to just blow open circuit. I didn't overload it or anything, and the tube was working fine. I was always scared to turn it off because it may not work again. Well, this time it actually happened.
Edit:
Another edit: I finally got it to heat up evenly and it has been on for some time now, but oddly i killed 2 RF bypass caps and my screen transformer, so back to solid state for awhile. Not to mention, the tube is just going to do the same thing all over again.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
So how did you get it to heat evenly? Maybe your blown rf bypass cap was drawing the current out of one half of the filament? Btw. I have seen this mode of failure on this tube, but I have no idea how it happens.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Dr. Kilovolt wrote ...
So how did you get it to heat evenly? Maybe your blown rf bypass cap was drawing the current out of one half of the filament? Btw. I have seen this mode of failure on this tube, but I have no idea how it happens.
Once the bypass cap blew, i took it off. Also, it would just effectively short the plate and the cathode. I checked all my connections and the filament connections touch nothing other than the transformer and the RF bypass cap in parallel (not sure if that is even needed considering there is a tap in the middle of the filament, i figured i'd rather take 5 minutes and put on a cap than burn the filament up). Im still guessing it has to do with the poor (or non-existent) packaging, if anything. My tube hasn't been bumped or vibrated, overvolted etc. It has also never been started without a filament resistor.
And i got it to heat evenly by turning it on for a long time with the filament resistor. After those started melting ( ) i just figured i would try bypassing them. It kept doing the same thing, but finally one of the times i bypassed it it heated evenly. But, i turned it off, and now i can't seem to get it back on.
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.
GU-81M datasheet.
) i just figured i would try bypassing them. It kept doing the same thing, but finally one of the times i bypassed it it heated evenly. But, i turned it off, and now i can't seem to get it back on.