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Re: [Amps] glass tape scotch 27

Subject: Re: [Amps] glass tape scotch 27
From: "Will Matney" <>
Date: Tue, 13 Jun 2006 14:31:22 -0400
List-post: <>
What I'm wondering is why one would need a tape rated at 130 C (266 F)? The 
core should not get no where near that hot, maybe just warm to the touch which 
would be around 100-110 F (37.7-43.3C). Ferrite supposed to be non-conductive 
which would only leave sharp corners which can be removed easily with a piece 
of emory cloth if they have them. You can also place a wood dowell through the 
center of the toroid and use a wire brush wheel on a grinder to remove them 
very quickly from the O.D.. I generally just keep a piece of emory cloth on the 
bench and smooth them that way. It don't take too long to do it. I've seen many 
cores, both iron powder (which most has a painted coating), and ferrite without 
tape that has lasted for years. I wouldn't doubt that regular tape like the 
filament tape I mentioned would work just fine. Matter of fact, I know a 
company that used that tape to install the RF power meter in an amp which was 
mounted where the tubes were close, and heat actually mel
 ted the meter back when the fan quit. The tape was still ok. I cant see one 
vibrating enough to cause this either. If it does, something like the blower or 
fan is way out of balance, and ought to be replaced. The newer varnishes on 
magnet wire is pretty tough, especially if it has Teflon insulation like Teflon 
hook up wire. On toroids, you need all the space you can get to hold the wire 
if it will be a good amount, so a thin tape ought to be used if possible like 
Kapton. That is if any need be used at all like a good amount which does not. 
On input tune cores, tape means a lot of space where they are small. On output 
tank coil toroids for 80 or 160 meters, I've seen both taped and non-taped 
used. I just can't see where this expensive tape would be needed here for this 



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On 6/13/06 at 7:14 AM tim jenkins wrote:

>scotch 27 is high temp with thermosetting pressure-sensitive ashesive and
>operates at class b 130 deg C ( 266 deg F) temp.  tim kv4bk
>scotch 27 glass cloth electrical tape
>kv4bk @ amps4u
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