Message-ID: <3FB150A2.1020407@virgin.net>
Date: Tue, 11 Nov 2003 21:12:02 +0000
From: "Stewart Bryant" <stewart.bryant@virgin.net>
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Subject: Re: LF: Re: Dummy loads at LF
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When I was a PhD student we used to make high power resistors
to terminate very large pulse generators from PVC tube filled
with copper sulphate and with brass end plugs. By varying the
size of the resistor and the concentration of the copper sulphate
we could get the value we wanted. I can't remember how powerful
these generators were (not my project), but they ranged
from the size of a small van to a very large lorry :)

Interestingly the high frequency performance of these resistors
was not a problem.

A quick check on Google pointed me to this design info:

http://www.kronjaeger.com/hv/hv/comp/res/
(It's actually interesting to also look at the top level page)

http://www.samtech.co.uk/PDF%20files/liquid%20res.pdf

73

Stewart

Johan Bodin wrote:
> Dear group,
> 
> at a wavelength of 2200m I can't see any reason why a bucket of
> salt water can't be used as a "poor man's dummy load". Also,
> water needs a lot of energy to heat up. At 4.18 kJ/(kg*K) a 10 liter
> bucket will take a kWh, or so, before reaching the boiling point...    :-)
> 
> By the way, the speed (frequency) control system at SAQ contains
> servo controlled "liquid rheostats".
> 
> Any ideas for electrode material?
> 
> 73
> 
> Johan SM6LKM
> 
> 
>