I just checked a Dale old school 'sand' wirewound, swept from 1.79 to 4.33.
100 ohms, 3 watts. R ranged from 100 to 102. X from 12 to 13. Swr was 2.1
to 2.0, all readings from lo to high vs freq.
Next I tried a gold colored encased power resistor w two bolt holes, at
olpposite ends.
At 1.7625, R=5, X=0, swr = 8.8
At 4.3305, R=7, X=9, swr = 9.1
Marked 8 ohms, 5 percent, 25 watt.
Didnt have the values you NEEDED, but it would seem that at 1.8-2, 6 or 7 of
these aluminum encased style would work.
Transistors have ratings, tubes have guidelines!
--Shane
Kilowatt Delta Six Victor Xray India
-----Original Message-----
From: pc5m, Carel <pc5m@xs4all.nl>
Sent: Monday, April 18, 2011 02:15 AM
To: Amps@contesting.com
Subject: Re: [Amps] wirewound resistor inductance/capacitance parameters
Jim, thanks for your reply, however my goal is to see what can be
done with those low cost chassis mount resistors. The non-inductive
one's (or special thickfilm resistor) are much more expensive....
So,
I was hoping that someone had taken some data for those low cost ones?
In the meantime I did take some crude RF measurements and two 100 Ohm
50W resistors in parallel gave a 1:1.2 SWR (-20dB RL) at 2 MHz. That is
encouraging...but before I order a massive amount I would like to limit
the risk a bit more...
73's Carel.
On Sun, 17 Apr 2011 18:14:31
-0700, Jim W7RY wrote:
> There are LOTS of non inductive resistors out
there (thick film etc)!
> Consult the Mouser catalog. Download a Mouser
catalog at
>
> www.mouser.com [6]
> 73
> Jim W7RY
>
>
--------------------------------------------------
> From: "pc5m, Carel"
> Sent: Saturday, April 16, 2011 8:37 AM
> To:
> Subject: [Amps]
wirewound resistor inductance/capacitance parameters
>
>> Hi, Was
wondering if someone had some RF data (inductance/capacitance, or even
better a spice model..) of the general available low cost aluminum
housed high power (e.g. 50W) resistors for chassis mount? Example are
the Vishay NH series ( http://www.vishay.com/docs/30201/30201.pdf [2])
but also Welwyn and Ohmite run comparable products. Goal would be to
construct some high-power (kW's) dummy oad for 160mtrs (so only
reasonable well reflectionloss needed till 2 MHz..). Did google a bit
but didn't found anything useful. Thanks in advance, Carel
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[2]
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