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 #1643
Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039
I second Mads Barnkob. I use to use poly acrylic, as it did wonders for my first coil, but i found out if you want mirror finish, polyurethane is the best. I go for the see-yourself-finish...I typically do 7-10 layers, sand with 600... repeat that 3 times, then 7-10 layers -- sand with 800, repeat 3 times... then work my way to 1500 grit, repeat 3 times, final product is mirror. Lot of work, but its worth it for me, because i love the finish :)
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
Liquid Polyurethane "floor varnish' works well and a gloss finish can be achieved with a 'thinned' layer first to penetrate the windings then a couple of thick layers without sanding ...need to mount the coil on a motorised device to keep the coil rotating whilst drying OR apply many thin coats.
'Yacht varnish' gives a nice hard finish.
A thin coating is probably better than a thick one as quite a lot of 'static' charge can accumulate on a thick varnish layer and 'zap' you, not dangerous but annoying.
A thick coating does look better and provide protection against accidental 'nicks' in the wire/winding.
P.S. I don't think that the dielectric loss of the varnish is important at all.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Thanks for the replies. As for the losses, I was trying to design an RF choke for a 30 MHz oscillator. The first coil which I dipped in varnish was burning hot, the second one was the same but parafin wax coated, it was better but still hot. The last one was wound with a gap between the turns and this one remains cool during operation. So there are indeed some losses in the varnish, but if they're important at usual TC frequencies, I don't know...
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Dr. Dark Current wrote ...
Thanks for the replies. As for the losses, I was trying to design an RF choke for a 30 MHz oscillator. The first coil which I dipped in varnish was burning hot, the second one was the same but parafin wax coated, it was better but still hot. The last one was wound with a gap between the turns and this one remains cool during operation. So there are indeed some losses in the varnish, but if they're important at usual TC frequencies, I don't know...
Another factor would also be the cooling, a open coil will have a much larger surface to dissipate heat from than a varnished coil.
Registered Member #2292
Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795
I used to use polyurethane varnish, but after working with epoxy for a while now I much prefer it over poly for a couple of reasons. First of all you only need one coat and it's a rock hard hard coating that stands up to racing sparks very well.
It you end up using it make sure you have a blow dryer handy for getting rid of the bubbles that form when poured. Suppose one could also de-gas it by putting it in a vacuum before pouring it.
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.