Building a saltwater dummy load

[Deleted User 30222]

In the process of building my own saltwater dummy load. For 2 reasons. Trying to save a few bucks, and for the fun of it. You know, just so i can say i did it.
Though **Censored** came out pretty well. Then i went to check it with a meter. I never seem to get the same reading twice. It also drifts, not showing a constant reading. Another thing is that i have to set my meter on the 20k setting. And i have already added a pinch of salt. Any help would be greatly appreciated :D


I soldered the electrodes directly to the bolts

[iparodyall]

Well i don't know anything about it but it looks cool, good work

So what are you using a dummy load for, i don't know much about radio tweaking and such

[Deleted User 30222]

It's used for testing and adjusting your radio. It gives a more steady signal i believe.

[Blue Ox2]

There was a project in QST making dummy load and frequency meter.

The project uses Mineral oil as the medium in the dummy load.
Perhaps that is part of the issue.
I don't know, just a thought.

73,

Mike

[295 antenna]

A Dummy Load is a device used to simulate an electrical load during testing. In an RF System a dummy load is used to simulate an antenna. By using a dummy load instead of an actual antenna, the transceiver can be tested and configured without radiating radio waves.

[Lost Ram]

To much power might make chlorine gas!!!!!! I would skip that and go with a build using mineral oil and resistors. You can tune that to what you want and it will be set forever provided you dont exceed its burn up level, IE to much wattage, LOL. Saltwater between to electrodes makes chlorine gas, albeit, its a lot voltage and amps to make it happen. I just dont find that to safe at ALL. I SAY STOP THAT ASAP!!!!!!

[nosaj]

i have a cantenna, here is th heathkit manual[Please login or register to view this link]
nosaj

[MDYoungblood]

Don't know about chlorine gas, the average CB radio doesn't make enough wattage to boil the water much less make it hot. I built one out of a gallon jar and used it to test/tune my Henry 4K, never got hot.
Lost Ram did make me think the water (tap water) you are using might be your problem, there is a lead content in a lot of municipal water systems. I used distilled water from the grocery store, no minerals or chemicals in it.
I think the coax might be a problem too, the 2 electrodes are seeing the shield, it will also see you, the metal stuff around it. Try moving the terminal lugs on the lid toward each other.

3's

Greg

[Deleted User 30222]

Right now i'm using a large plastic peanut butter container. Must be about 50 oz. Tap water also crossed my mind. Specially after hearing the latest in the news. I'll give filtered water a try. I will move the lugs closer together. But the electrodes need to be spaced...Correct?

[Bluerunner]

I don't think you will get a relevant reading with an ohm meter. Need to test it with a radio & SWR meter.

Keep adding a bit of salt and see if the SWR goes down each time.

[MDYoungblood]

Right now i'm using a large plastic peanut butter container. Must be about 50 oz. Tap water also crossed my mind. Specially after hearing the latest in the news. I'll give filtered water a try. I will move the lugs closer together. But the electrodes need to be spaced...Correct?

Use distilled,, not filtered water, it will be free of any conductivity minerals. The electrodes can be closer together, as long as they aren't touching they will only react to the saltwater. See if you are getting any kind of reading without water first, if you are then something is reacting with the way you made it.

3's

Greg

[scottj]

i have a cantenna, here is th heathkit manual[Please login or register to view this link]
nosaj

Thank you for posting this!

[Deleted User 30222]

It's the cable. Not sure how that slipped by me, i always test em out. I'll try and get it done tonight and let you know tomorrow.

[Deleted User 30222]

Well the cable is done. And it tested ok. So now i'll try some distilled water now. And if i decide to move the lugs closer together. What do i do about the old holes in the lid. Or do i need to get a new lid.

[MDYoungblood]

Well the cable is done. And it tested ok. So now i'll try some distilled water now. And if i decide to move the lugs closer together. What do i do about the old holes in the lid. Or do i need to get a new lid.

Eat another jar of peanut butter and start over,, :D :D :D

3's

Greg

[Deleted User 30222]

Ok, finally picked up some distilled water. Put my meter on it. The only time i get a reading is when the meter is set to 2000k. Is that right? And i read that my electrodes should go down to about 1/4 - 1/2 inch from the bottom. Mine is about a inch. Do they need to be a little longer? Also, my multi-meter had it's leads cut. I did solder them back and wrapped in shrink tubing. Did that just change the resistance of the meter. Do i need new leads?

[295 antenna]

I think that you could check your leads on a known measurement . That would tell you if they are working correctly.

[Deleted User 30222]

Ok I just took a 220 ohm resistor, checked it with my meter. And it's dead on at 220. Just to be sure i took a 100k, it reads 100.4 So maybe it's good.

[295 antenna]

Sounds like it to me . now make your electrodes like they are supposed to be ? I would.

[Bluerunner]

I used to work with 800HP 480 vac gas turbine generators. We load tested them in a very big tank of salt water using 4' X 8' steel grating as the electrodes hung from a crane. Very energetic reaction when you closed the breaker.

Never thought about it as a RF dummy load. I'm gonna try it too just because I can and it is a way cool idea.

Thanks for the great ideas.

[dime196604]

Just hook up a radio and add little bits of salt to lower SWR. Your never gonna read 50ohm of resistance with a multi meter. Its 50ohm of impedance your looking for. Made mine with tap water, SWR was up to about 2.1 with no salt added. Added a pinch of salt and it went down to 1.1, that was 8 years ago. other than the lid rusting over time no other issues and still has low SWR

[MDYoungblood]

Just hook up a radio and add little bits of salt to lower SWR. Your never gonna read 50ohm of resistance with a multi meter. Its 50ohm of impedance your looking for. Made mine with tap water, SWR was up to about 2.1 with no salt added. Added a pinch of salt and it went down to 1.1, that was 8 years ago. other than the lid rusting over time no other issues and still has low SWR

I built mine out of a gallon pickle jar (wide lid) and I did use a multi-meter to get 50ohm resistance and reactance at the connector, in other words "impedance", "Z = R + iX" (put this in for those math nuts).

3's

Greg

[Deleted User 30222]

So am i to understand that i'm NOT going to get a 50 ohm reading. And is it really safe to just connect it without knowing. Don't want to blow my baby up.

[Deleted User 30222]

Well i decided to just plug it in and try it. Had a SWR of 1.7 from 1-40. Added a pinch more of salt, now have it down to 1.1 - 1.2 threw the band.

[Blue Ox2]

Cool Beach. Glad to see yer efforts are paying off.