Tim, N9PUZ writes to the HamRadioHelpGroup mailing list:
With new HF rigs being 100% solid state these days, the need for a dummy load in some shacks has gone away. However, if you have an amplifier they are very useful as you can do most of your tuning off-air and avoid causing QRM.
Recently, I bought a used Heathkit Cantenna. It is a dummy load similar to the MFJ-250 1kW “wet” dummy load. It did not come filled with oil due to shipping difficulties.
In many places, such as where I live, genuine transformer oil to fill the load is unobtainium. You can buy a gallon from MFJ but it costs $30 plus shipping.
According to the Heathkit documentation, a good substitute is mineral oil. I checked at the local pharmacy and they wanted $4.25 per PINT still making this an expensive proposition. I wouldn’t classify myself as cheap but I am frugal so I kept searching.
An Internet search led to my discovery that mineral oil is often used as a laxative for horses and other farm animals. A quick trip to our local farm store “Farm and Home” got me a gallon jug for just $15. I imagine any store of this type or even the local Vet would have some.
The amplifier tunes up into the Cantenna very nicely now. Life is good.
This is a great tip, but I disagree that “the need for a dummy load in some shacks has gone away.” Every shack should have a dummy load. They are immensely useful, especially in situations where you’re not whether your antenna or your transmitter is what’s causing you not to transmit properly.