[Amps] Dummy Load Blues

[Bryan Swadener]

> From: Glen K9STH
> Subject: Re: Dummy Load Blues
> 
> Before purchasing any transformer oil, go by your local
> electric company service center. The electric companies use
> transformer oil by the 55-gallon drum. Offer to buy a
> gallon. The vast majority of service centers will just give
> you a gallon because the paperwork to sell a gallon costs
> considerably more than what the gallon costs. You might
> take a dozen donuts along with you to "sweeten" the deal.
> However, at least around here, even the "gift" is usually
> not necessary.
> 
> You might take along a container that holds more than a
> gallon because it is difficult to get just a gallon out of
> the containers.
> 
> By the way, transformer oil is MUCH better than mineral oil.
> If you have to have mineral oil go by a farm or ranch
> store. They sell mineral oil by the gallon cheaper than you
> can buy a pint in the drug store.


There's an echo in this thread.  I stated that a few days ago.  I would not use any kind of mineral oil because it won't cool as well as xfmr oil.  For a DL like the Cantenna, if you intend to use it with much more than the resistor's rating of 90W, you're best-off to use xfmr oil.

However, I wouldn't just "go by" my electric company's transformer shop (or "service center") for xfmr oil.  When I refurbished my HN-31 Cantenna, I made a few calls to track down the supervisor for my electric utility's transformer shop and asked if I could buy a gallon.  He said he would be happy to GIVE me a gallon, and no gratuity was necessary.  I then made arrangements to collect the oil.  Since then, I use the DL for ONLY low power (up to ~100W) tests since it's marginal for high power stuff.  My FREE homebrew air-cooled DL can take 1600W (100% duty-cycle) up to 50 MHz all day.

vy 73,
Bryan WA7PRC