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 #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
Well the grounded shielding has a large parasitic capacitance to the resistor, if that was all there was to the probe then for higher frequencies most of the signal gets coupled to the shielding long before it gets to the low voltage arm of the divider (the electric field along the resistor is no longer symmetrical like it is for instance with your resistor from the other threads with the hoops). I assume the leaf capacitor is not grounded, but connects to the low voltage arm ... so I assume it's there to couple the high frequency components to the low voltage arm to counteract the effect from the shielding ...
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Pinky's Brain wrote ...
Well the grounded shielding has a large parasitic capacitance to the resistor, if that was all there was to the probe then for higher frequencies most of the signal gets coupled to the shielding long before it gets to the low voltage arm of the divider (the electric field along the resistor is no longer symmetrical like it is for instance with your resistor from the other threads with the hoops). I assume the leaf capacitor is not grounded, but connects to the low voltage arm ... so I assume it's there to couple the high frequency components to the low voltage arm to counteract the effect from the shielding ...
Do you mean the 1k (R111) hold up resistor...at HF the 1k (Common Cartbon Comp, 1/2 W) can get much hotter then the HV resistor! charging 3pf and discharging at 75Mhz and 200v must make a lot of heat.
the coax cable, the length from the probe can end, torwards the comp-box spans 10Ft and the center strand has 225K resistrence. therefore 225K/10ft = 22.5kohms per foot.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
Patrick wrote ... Do you mean the 1k (R111) hold up resistor
With low voltage arm? I mean the 1K resistor and everything to the right of it in the schematic.
To me it seems that a handheld probe is significantly harder to design than a standalone probe connected through a low induction copper strap. With a stand alone probe you can keep the electric field across the HV resistor uniform (like your capacitive hoops in the other thread) which simplifies modelling it's operation.
The moment you put a grounded metal shield around it which goes close to the tip the behaviour of the system becomes much harder to predict.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Pinky's Brain wrote ...
To me it seems that a handheld probe is significantly harder to design than a standalone probe connected through a low induction copper strap. With a stand alone probe you can keep the electric field across the HV resistor uniform (like your capacitive hoops in the other thread) which simplifies modelling it's operation.
The moment you put a grounded metal shield around it which goes close to the tip the behaviour of the system becomes much harder to predict.
The NorthStar's do have a large topand bottom ring, to equalize the field and as you said I guess thats where some capacity comes from too.
I believe the Tek P6013, P6014, P6015 all have that metal shield so they can treat the whole path as a lossy-transmission line?
What about this...
Yellow are copper "Park-like" Caps, Red are resistors. The bottom most section are where compensation and LV componets live.
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.
Internals of a Tek P6013A HV O-scope probe.
