Topband: Non-inductive resistors.

Joe Wilkowski k8fc at k8fc.com
Fri Dec 19 12:17:18 EST 2003


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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