[TowerTalk] Fwd: Fwd: Oil For Dummy Load

Hans Hammarquist hanslg at aol.com
Fri Dec 4 13:19:54 EST 2015

Water has a very high dielectric constant, around 80, and it is a lousy dielectric with high losses at any frequency you want to use it for. On top of that, even distilled water is conductive if even so little. Once it get in contact with any metal it will start to dissolve the metal and become ionized = conducting.

Other than that, water would be very good for na dummy load with its high heat capacity.

hans - N2JFS

-----Original Message-----
From: TexasRF <TexasRF at aol.com>
To: hanslg <hanslg at aol.com>; towertalk <towertalk at contesting.com>
Sent: Fri, Dec 4, 2015 12:45 pm
Subject: Re: [TowerTalk] Fwd:  Oil For Dummy Load

What is wrong with using distilled water, $1.50 per gallon at Walmart? Works just fine for amplifier cooling, no problem at 2000vdc and 1296 MHz. Not flammable either!
Gerald K5GW

In a message dated 12/4/2015 11:33:46 A.M. Central Standard Time, towertalk at contesting.com writes:
I dime   in the discussion, why not use something with the lowest viscosity such as   kerosene. That way the heat would be more efficiently removed. Kerosene has a   relatively low flam point so, unless you allow the temperature to rise too   much.

I, myself use a home made dummy load made from resistors   packed in TO-220 capsules and mounted on a large, flat heat   sink.

Hans - N2JFS.

-----Original   Message-----
From: Bryan Swadener via TowerTalk   <towertalk at contesting.com>
To: 'TowerTalk'   <TowerTalk at contesting.com>
Sent: Tue, Dec 1, 2015 6:44 pm
Subject:   Re: [TowerTalk] Oil For Dummy Load

Gary K4FMX asked only about the   derating chart.

Fortunately for myself, oil viscosity is immaterial   
since my HN31 won't ever see more than ~ 100W again 
and I'll never   need to change the FREE transformer oil. 

Instead, for high power   stuff, I use my scrap parts 
1500W (100% D/C) DL that uses small   flange-mounted 
RF resistors. It's actually smaller than my HN-31.   

vy 73,
Bryan WA7PRC

----- Original Message   -----
> From: D. Scott MacKenzie
> To: Bryan WA7PRC
> Sent:   Tuesday, December 1, 2015
> Subject: RE: [TowerTalk] Oil For Dummy   Load
> Unfortunately they don't give the viscosity of the   oil.  Most transformer
> oil is mineral at a viscosity of 10-20 cst   @ 40C.  However, mineral oil can
> range from 10-1000 cSt.  An   identical viscosity mineral oil would perform in
> an identical   fashion.  
> -----Original Message-----
>   From: Bryan WA7PRC
> Sent: Tuesday, December 01, 2015 12:53 AM
>   To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Oil For Dummy   Load
> The chart is here:   http://www.tinyurl.com/wa7prc-cantenna
> My scrap parts 1500W   dummy load is here: http://www.tinyurl.com/wa7prc-dummy
> Though all the   parts were free to me, outfits such as Henry Radio
>   (http://stores.ebay.com/Henry-Radio) sell RF power resistors for   reasonable
> cost on ebay.
> vy 73 es gl,
> Bryan   WA7PRC
>>  Date: Mon, 30 Nov 2015
>> From:   Gary K4FMX
>> Subject: Re: [TowerTalk] Oil For Dummy Load
>> There used to be a chart on the side of the Heath cantena that   showed 
>> the difference between transformer oil and mineral oil as   far as 
>> power/time. As I remember it was rather a significant   difference.
>> 73
>> Gary    K4FMX

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