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Re: [TowerTalk] Heath Cantenna

To: "Michael Tope" <W4EF@dellroy.com>,"Towertalk" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Heath Cantenna
From: Jim Lux <jimlux@earthlink.net>
Date: Mon, 07 Jun 2004 11:00:30 -0700
List-post: <mailto:towertalk@contesting.com>
Mineral oil and Transformer Oil (i.e. Diala AX) ARE the same thing... The MSDS for Diala AX says that it is mineral oil (more precisely: highly refined petroleum oils).

Maybe it's a viscosity thing... Mineral oil from the drugstore comes in several viscosities. Diala is pretty non-viscous and runny (not as thin as water... about like room temperature cooking oil)

The other differences are subtle chemical things. USP mineral oil has a limit on PolyAromatic Hydrocarbons (PAHs) which are potentially carcinogenic (if you immerse yourself in the stuff for long periods of time, there's an increased incidence of testicular cancer... in the context of oil mist/spray from machining operations), while transformer oil doesn't claim to be particularly free of it.

Diala is also slightly yellowish (straw colored), while USP mineral oil has to be "water white". However, that's not due to particulate contamination (i.e. soot) which would kill the dielectric properties, but due to less refining of the oil, so there are some colored compounds in there (probably things with benzene rings...PAH's among others).

$25/gallon for the real thing is quite high... Unless it included shipping and tax, considering you can buy 5 gallons for under $30. Somehow, I doubt MFJ is going to certify the water/contaminant content, as delivered, too.

http://www.shell-lubricants.com/products/product_list.php?subcatid=26

Here's the Diala A and AX data sheet:
http://www.shell-lubricants.com/products/pdf/DialaA&AX.pdf

There's also a Diala M
http://www.shell-lubricants.com/products/pdf/DIALA%20OIL%20M.PDF

and HFX, which is fire resistant
http://www.shell-lubricants.com/products/pdf/DIALA%20OIL%20HFX.PDF

At 09:07 AM 6/7/2004 -0700, Michael Tope wrote:
----- Original Message -----
From: "Jim Lux" <jimlux@earthlink.net>

>
>
> Thermal properties are basically the same as USP mineral oil (drugstore
> oil).  The big differences:
>

Jim are you sure about that? The reason I ask is that both
the Heath and the MFJ Cantenna style dummy loads specify
duty cycle curves for mineral oil and "transformer oil". For
1KW, the duty cycle for mineral oil goes to zero, whereas they
specify 10 minutes (I assume this is from a room temperature
oil baseline) for transformer oil. Either Heath and MFJ cooked
the numbers to sell more transformer oil (MFJ sells it for
$25/gallon), or "transformer oil" is actually better at pulling heat
away from the Carborundum resistor.

In any case, if this is wrong, I would like to know. Getting
mineral oil in small quantities is a lot easier and cheaper than
trying to find real transformer oil.

73 de Mike, W4EF...............................................



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