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Topband: Non-inductive resistors.

To: topband@contesting.com
Subject: Topband: Non-inductive resistors.
From: Joe Wilkowski <k8fc@k8fc.com>
Date: Fri, 19 Dec 2003 12:17:18 -0700
List-post: <mailto:topband@contesting.com>
Folks, there has been an overwhelming response to my inquiries.  Thanks to 
everyone who has responded.

FYI here is a synopsis:

:: Try Digikey  www.digikey.com  Navigate to this part number after some 
research at Ohmite http://www.digikey.com/scripts/DkSearch/dksus.dll?  These 
are non-inductive 2.5 watt high energy absorbing ceramic axial lead resistors.  
They do not have any values below 1 k so it would take 4 2.2 k resistors for 
each termination.  Resistor cost $9.25 each US.  Part number for these is 
AX22GK.

:: Ohmite www.ohmite.com 

See above information

:: Riedon  www.riedon.com 

Riedon carries only wire wound and thick film resistors.  (See later comments 
about metal film resistors and make your decision) I am still only interested 
in composition non-inductive resistors so will pass on Riedon.

::  www.tubeampparts.com  Specifically 
http://www.tubeampparts.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=A&Category_Code=2WNCC

These are a bit more reasonable at about $3.00 each.  They do not have any 
resistors in the 450 to 470 ohm range but have other values to be paralleled 
for desired resistance.

:: www.mouser.com Specifically 
http://www.mouser.com/index.cfm?handler=search.processsearchb  and search for 
TCH35P-470 these are 20-35 watt thick film (metal) resistors and are about 
$5.85 each.  They come in a TO style case.  Again these are metal film 
resistors.

Also, Mouser has Caddock non-inductive power resistors rated at 250 volts and 
30 watts.
Brad KV5V also recommends 2 watt carbon composition resistors from MC Howard in 
Austin, Tx at 512-837-2525.

Also mentioned by a number of respondents ::
I usually parallel several of the lower wattage carbon compositions to
create the 500 or so ohm resistance.  I used 4 ea  2,200 1/2 watts in
parallel.

If you can't find the "real ones" that may work.  I have had some success
that way with my 160 meter Beverages.

Other comments have been previously sent to the reflector on the usability of 
metal film and other resistors with varying amounts of inductance per resistor. 
 I will not repeat those here as they have been published already.  Suffice to 
say, due to the low nanohenry levels of inductance of these devices at 2 MHz 
the opinion is that the resulting inductive reactance is insignificant in 
changing the phase angle of the received signal.

Happy Holidays to you all, and once again thanks for the support.

/joe k8fc




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