[Amps] Can distilled water be used for a dummy load ??

[Jim Thomson]

Date: Fri, 2 Dec 2011 11:24:57 -0500
From: "Paul Christensen" <w9ac at arrl.net>
Subject: Re: [Amps] Can distilled water be used for a dummy load ??

> Altronics and other Broadcast loads immerse the resistor IN the fluid
> ( 50/50 distilled  and glycol ) . The fluid flows through the hollow
> resistor and returns over the outer surface allowing the most surface
> area to be cooled by the fluid.

Glycol is not a requirement with the Altronic Omegaline.  It works with 
running tap water from a common faucet to a drain or sink.  It's that 
simple.

Paul, W9AC

## But running tap water is NOT a closed loop system.  Now on some of these
closed loop setups, they will use a 1500 gal tank  and a pump..and no heat exchanger/fan.
Some will use  a smaller tank and a HE + fan.   Some may have the tank located such that their
might be a concern with freezing, and/or corrosion problems inside the rad, etc. 

##  OK,  I think I have come up with a unique, viable design.  I could take my existing 7 gal
dummy load, and install a pair of standard 3/4" garden hose type fittings to the top lid, say one
towards the outer edge, and the 2nd one more towards the coax connector, or beside it. 

## The 1st fitting would have a tube attached to the inside of it.... extending down to the bottom of the
7 gal container.   Call that 1st fitting the intake.    2nd fitting, next to the coax connector is the OUTPUT,
and no internal tube connected to it.   Then just run a hose form cold water tap to the intake....and of
course a 2nd hose from output of dummy load.... to the nearest drain. 

###  Then just turn on the tap full bore..and blast away.  COLD water comes into the 1st fitting, next to the outer
edge of top lid, then straight to the bottom of the 7 gal can, via the internal tube.  The resulting water flow will be
from the bottom of the 7 gal can towards the top of the can, right flush to the inside of the top lid  [no 1" air gap layer]
Then out the 2nd fitting to the drain.  Now the slick part is, even with the tap shut off, there is always 7 gals  of water
sitting in the tank at all times ! 

##  For some applications, 7 gals of room temp water sitting the can  will be ample for some testing, etc, or until
can gets too hot.   Now for more demanding applications, say more average power, or extensive testing on each band,
including tweaking PI nets, changing  loaded tank Q, changing bias V on the fly, or anything else, then  simply turn on the
tap  just a small amount, or  say some where between 1-6 GPM, and now you have a dummy load that will handle
the job.   Even with 1 GPM, the fresh water coming in will be COLD.     

## The worse that could happen is the 7 gal tank started leaking.   Since the 2 x garden hose fittings are on the top lid, even they
would not be a problem.   It still baffles me why it's ok to stuff 500-1000 vrms  into tap water, and nothing conducting. 
I will 1st try the water with the 1 gal heath cantenna load.  [using a new 1 gal can]  and run some tests, like any V break down,
swr changes, try 160-10m, temp rise, etc. 

###  what's unique abt the proposal is, it can be used with or without  tap water as required.  Heck, the same stunt could
also be used on a  new 1 gal can, with the heath oem 90 watt resistor.  With 1-6 GPM flowing through a 1 gal can, with
the 90 w heath resistor, you could probably  diss a heck of a lot of average power. 

What do you think?   There could be a concern with how the water flows past the 4 x ressistors though, but with enough GPM
I don't think it would be an issue.   It would be a cheap and quick way to make a high power dummy load, that can also have
it's ratings further increased, just by turning on a tap.  I see no reason why  240 vac could not be applied for some initial testing,
[using fuses/variac etc].  240 vac into 50 ohms = 1152 watts CCS.  Then no RF required for initial testing. 

Later..... Jim VE7RF