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[Amps] winding forms for coils and glitch resistors

To: <amps@contesting.com>
Subject: [Amps] winding forms for coils and glitch resistors
From: 2@mail.vcnet.com (Richard)
Date: Thu, 25 Apr 2002 13:07:25 -0700
>-
>>>Is there any mileage in making a home brew glitch 
>>>resistor for use in series with the B+ using Nicrome 
>>>wire on a 1 inch diameter ceramic former? 
>-
>#  I would build one out of grooved Delrin or ABS 
># tubing and Ni-Cr resistance wire.       
>-
>One group of people I work with will often wind 
>their own coils. I've noticed one person found and 
>purchased large diameter plastic screws, probably 
>from a Company like McMaster Carr in SoCal. 
>-
>I haven't had time to check the rf properties of this 
>plastic, 

ABS and other styrenes have a low dissipation-factor.  Delrin has a 
medium dissipation-factor.  When a commercial "3kW" tuner, which used a 
Delrin roller coil form, was tested in the ARRL lab, the roller coil 
reportedly melted and ignited. 

>but they are winding up a storm for NMR 
>probe coils.  They seem to be transparent to RF in
>the 45-330MHz range.  Heat is not an issue in 
>their current applications. 
>- 
>Might be a source of  a "poor mans coil form" which 
>works out well.  

For up to a few hundred kHz, Delrin is not terrible.  

>The home brew coil is much more 
>rigid/stable on these large plastic screws. Looks 
>like I'll be looking into the source of the bag next 
>trip in (later today). 
>-
>skipp
>
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-  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, 
www.vcnet.com/measures.  
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