Experimental chemical dummyload

First experiment...

 I while ago I did read a article on AE5X's blog about a "chemical impedance matching dummyload". 

Fair enough it looks easy to reproduce. This looked like a very easy and fun experiment, but is it that simple?

I built my first version with 2 RVS bolts about 4 cm spaced and about 4 cm in the water mixed with a spoon of baking powder. It didn't work out, the SWR was 1:5. So, I tried another spoon with baking powder, nothing changed. I did remove some of the water, nothing changed. So I guessed the size en the length of the electrodes could be important. Or it might be the amount of water? Or even the amount of power? Joe WB9SBD didn't mention anything about it. 

So, I decided to write Joe an e-mail to ask for the size of his electrodes and the amount of baking soda. He told me the electrodes were made of #14ga wire, 5" long and about 4" was in the water. Spacing is about 1". I quickly converted it to metric. Normal electrical installation wire with removed isolation is about 2mm thick, they should be about 13 cm long and about 10 cm should be in the water. A theaspoon of baking powder mixed with water is more as enough. I took a big 1000gr. peanutbutter jar and mounted everything the right size. However, although a exact copy from Joe his experiment he already uses for 10 years, the SWR was now still 1:3! Is it a difference of dutch water compared to water in the USA? Is it a different kind of baking powder? Or may be the wire diameter or material has influence? So, just to experiment I pulled the electrodes out of the water to see what happens? And now, indeed I see the SWR going to almost 1:1. I removed some of the water until I finally had a reasonable SWR from 160m-10m. But now the electrodes are about 1 cm (0,4") in the water, actually they just dip into the water.

I also checked the dummyload with the MFJ259 analyzer. It shows 52 Ohms from 1,8 to 14 MHz, but then it's rising till 88 Ohms on 29 MHz. Joe did have a complete different experience with good SWR till 180 MHz!!

Well, this was a nice experiment but not 100% reproducable. There are some variables that seems to have a influence. 

- electrode wire material?

- electrode wire diameter?

- electrode length?

- electrode spacing?

- Water difference?

- Bicarbonate difference?

- Amount of bicarbonate

- Length and type of coax?

In the video I like to say "sodium bicarbonate". It's the same as natrium bicarbonate or bicarbonate. baking powder, baking soda. Some will say baking soda is three times stronger as baking powder?

If anyone likes to try this experiment, let us know what you discovered. 

Update 06-Nov.-2020: Joe did write me an e-mail about the difference between baking soda and baking powder. Someone else did comment on the post with the same outcome.

Baking SODA and Baking POWDER are totally different chemicals.

I do not know what POWDER's properties are.

Soda is

NaHCO3. It is a salt composed of a sodium cation (Na+) and a bicarbonate anion (HCO3−)

Powder is,

Part Baking Soda, but also some sort of an acid and a buffer of most times corn starch.

So the extra ingredients of the powder might be messing with the Ions,

Also if you started with a teaspoon worth you may have gone below 50 ohms at first try.

what is the SWR and impedance of just plain water?

Then add just a tiny bit of actual SODA, mix well till 100% dissolved, and let it "Rest" for say 5 minutes so the SODA fully mixes with the water. Then test and see how things moved compared to the plain water.

Joe WB9SBD

Interesting, so there is at least a difference. I will take his advice and see what SWR of plain water is. Then add small bits of baking soda to see what it does.