Questions tagged [dummy-load]

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9 votes
1 answer
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How do I know if my dummy load is working?

I understand why a dummy load is used, but (aside from it getting hot) how do I know if it's doing it's job and doing it's job well? In my specific case, I'm using a Hack RF One SDR and a Souked SMA ...
M6JNY's user avatar
  • 356
9 votes
3 answers
304 views

Will there be common-mode currents if a coax followed by a ladder line is terminated in a dummy load?

Assuming an antenna system where a transmitter feeds an ideal coaxial cable which is then connected to an ideal ladder line without a balun: It is often said that common-mode currents appear in the ...
rubund's user avatar
  • 224
6 votes
2 answers
2k views

Dummy load construction and heat dissipation

I'm building my own dummy load, consisting of resistors submerged in liquid paraffin (or something similar, not 100% decided). I had some questions around heat dissipation and how I can calculate ...
David VK2VXK's user avatar
6 votes
1 answer
262 views

Why does adding 50-ohm BNC Ethernet terminator(s) in parallel to my 4-element yagi improve my radio's reception? (70cm)

I have this radio, with a rubber duck antenna, and a repeater twenty miles away to my north-northwest. If I set my radio on the top of a cabinet in my bathroom, I receive the repeater fine. I can't ...
CJ KE4EDD's user avatar
3 votes
1 answer
1k views

Using wirewound resistors in a dummy load

I have a bunch of high-wattage 50 ohm resistors lying around, but they are wirewound. If I use them as a dummy load for transmitters 144 MHz and down, how bad would that be? Since they probably will ...
Skyler 440's user avatar
  • 7,590
3 votes
1 answer
649 views

With solid-state equipment, when would one use a dummy load?

With vacuum-tube-based transmitters, you'd need to tune the output finals to achieve maximum power output, and this was commonly done into some sort of dummy load (either a purpose-made dummy load or ...
user's user avatar
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2 votes
3 answers
325 views

Does a paint-can dummy load have high voltage on the metal can? Would an insulated container be better?

I've seen many plans for 50 Ohm dummy loads in paint cans, such as the one here: https://www.nonstopsystems.com/radio/frank_radio_antenna_dummy.htm. I've already assembled a functional dummy load, but ...
Adam KC0DAD's user avatar
2 votes
2 answers
372 views

Identify this “large TNC” coax connector

I have recently acquired a nice looking dummy load on military surplus sale. Being relatively new to the hobby, I assumed the connector on it was something common. Turns out it is not. So far nobody ...
Mchl SP5MKL's user avatar
1 vote
2 answers
324 views

Can I use the dummy load provided with the nanoVNA for adjusting my QCX+

I don't see any mention about the dummy loads rating. Since I'm operating at $13.8~V$ the power output is about $4~W$. I'm looking to use what I have on hand as I have a field day approaching soon and ...
rsn's user avatar
  • 257
1 vote
1 answer
139 views

Diplexer termination?

When using a 2M/70cm diplexer for low-pass filtering (or with only one antenna on one of the two "outputs"), should the unused connection be left open, or terminated? (using a suitable impedance, ...
hotpaw2's user avatar
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