Know your dummy loads - How to pick the right dummy load for the job!

[@walterbrown8694]

In my career in development and test of military radar and other electronic systems, a dummy load choice was generally determined by the level of average power the source (transmitter) could be expected to deliver to the load plus some safety margin, depending upon the design and nature of the system under test or operating conditions. Name of the game: Don't damage the human participants or fry any of the equipment. (Worst case considerations usually prevailed when protecting the equipment - Ex. A 1 kw peak power output traveling wave tube in the 2 to 4 Ghz band only able to operate at 1% duty cycle, max. , so a 100 w dummy load would be sufficient)

[@michaelwinaker87]

Nice comparison of the three different dummy loads. But you didn’t give the information stated in your title. “How to pick the right dummy load for the job!” Does the load need to be sized for the device such as a 10 watt for HT or can I use a 100 watt dummy load on everything up to 100 watts.

[@FEPLabsRadio]

Good point!

[@TheSmokinApe]

DLs a super handy for testing, nice job 👍

[@FEPLabsRadio]

Thanks 👍

[@K7VZ]

"Total garbage" summarizes MFJ products. I have a similar looking Diamond DL-30A that works properly.

[@azarellediaz4892]

I’m new to the airwaves and all of this is rocket science to me. I understand that if I take a 100 watt 50 ohm resistor and solder it between the center tap and ground she’ll of an SO-259 connector I have a 100W dummy load? If so, how do I know what the frequency range would it work for if I don’t have your fancy tool?

[@FEPLabsRadio]

That would work at HF frequencies (up to 30Mhz). Past 30, you need to get a little more complicated. I haven't done a video on that, but there are several on YT.

[@Mister22x2]

I have the 300 watt MFJ and it works flawlessly across HF. And my cantenna does the job at higher power levels. I accidentally had the mineral oil in the cantenna boiling at 1700 watts on 10 meters. Woops!

[@FEPLabsRadio]

LOL! I don't have one of those, I did get an MFJ-267, which is a 1500W dummy/SWR meter combo device. I *might* have warmed it up more than once!

[@phillyedhrj]

Nice job, Jim! You could probably use the smallest one for testing a 9:1 balun. 😉

[@ronwolenski-n8wcr]

Wow, that MFJ 261 isn't just bad, it's pure garbage! I wondered if you might had dropped it and damaged it. I would take a ohm meter and see if it's 50 ohm, since it should be just a 50 ohm resistor. This is why you should test your test equipment.

[@DanielHallmark]

Maybe that one load is only for testing your 9:1 transformer for an EFLW.

[@FEPLabsRadio]

That's about all it's good for!

[@DonzLockz]

I like the one with the 40dB tap. I would use that to test for spurious emissions. You need to bin the little one. :(

[@jake30966]

Is there any way to test without one of they machines you were using ? I don't want to end up getting a dud one

[@FEPLabsRadio]

You can do this with a nanovna, or a tiny sa as well. Either one will show you the numbers. Buy the dummy load off of amazon, that way if it's junque, you can send it straight back.

[@45auto]

That's a real shame about the MFJ 261. I like the idea of not needing a cable or adapter. As I currently don't have any way test a dummy load you may have just saved me some heartache. Fortunately, the alternatives shown here are not significantly more expensive.

[@bradl2636]

Total newbie… Can you recommend a suitable dummy load set for a Yaesu FT-818ND (rated 6W) front and rear connectors and for miscellaneous HT’s (up to rated 10W)?

[@FEPLabsRadio]

Something like this (amzn.to/3AE9Rn6) or similar. Any dummy load will work, it just needs to be able to handle the power you're going to put into it. Getting a DL that's rated for 100W will work perfectly fine on a lower power radio. Basically, the more power the DL can handle the more you will pay. Those plug type dummy loads are nice, and a lot of people have had great luck with the MFJ one. Pretty much, if it is 50ohms, and shows you 1:1 (or very close ) SWR it will work fine.

[@bradl2636]

@@FEPLabsRadio Thank you for your comprehensive reply..!

[@TheGmr140]

Nice video

[@Zodliness]

Beats me why people repeatedly waste good money on non-functioning Chinese counterfeits just because they think they're saving money. 🤔😂