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Re: [Amps] fiberglas tape : summary

Subject: Re: [Amps] fiberglas tape : summary
From: "Will Matney" <>
Date: Fri, 16 Jun 2006 23:36:43 -0400
List-post: <>

All I know is they used this in a certain amp that used a quantity of 12 M-2057 
(modified 8908) tubes with an output of about 2000 watts PEP. The meter was 
mounted within 4-5 inches of the output tank coil and was not shielded. The 
meters I seen melt, but never the tape. The meter body looked to be made from 
styrene plastic like plastic models are. It would be the same white plastic 
they use now mostly on cheaper meters. This being the kind you can illuminate 
with a lamp behind it. I couldn't say what the fibers were in the tape, but 
they looked like maybe a glass type fiber, I'm not sure. The tape itself didn't 
melt, neither did the fibers. I know the manufacturer just used tape that they 
got the best deals on, so it could have been any composition. The tape they 
used was about 1-1/2" wide, not the 3/4" stuff but they both should be the 
same. I tried this with some 3M packing tape with the fibers, and it worked on 
some I home brewed. I think a lot is how close the meter is t
 o the tank circuit. On a tank coil using a toroid, I'm not sure but it may or 
may not work. I have used it on smaller toroids handling 100 watts in input 
matching circuits and it held up ok. On them though, the thinner the tape the 
better as you fill up the hole and don't have space for the wire if you get it 
too thick. The large toroids like used in the output tank wouldn't be bad as 
the hole is a larger diameter. Ferrite toroids though supposed to be 
electrically non-conductive and act like a ceramic. Iron powder though is 
totally different. I've seen plenty of coils and RF transformers wrapped on 
ferrite cores without any tape at all, and they lasted for the life of the amp. 
Iron though uses an iron powder which is pressed under great pressure and heat 
to make a toroid similar to the way they make powdered metal gears in 
automobiles. It is conductive.



*********** REPLY SEPARATOR  ***********

On 6/15/06 at 10:03 AM wrote:

>Thanks to all who responded to my query about fiberglas tape.  
>The consensus was that Scotch 27 is the thing to use.
>Other suggestions were for strapping tape (like for packages) which 
>might work OK, but I don't know.  Some of them have glass fibers but 
>some have nylon or polyester fibers.
>Scotch 33 and 88 were also mentioned, but they are definitely NOT 
>fiberglas tapes.  They are high-quality black vinyl electrical tape.
>tnx agn es 73,
>George T. Daughters, K6GT
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