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Author Topic: Questions about transceiver testing before license  (Read 461 times)

LINEAR

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Questions about transceiver testing before license
« on: October 19, 2022, 05:39:44 PM »

Hi guys, so, here's the story.

I've been meaning to get my technician license for a while, and finally sat down and read the official ARRL study guide cover to cover.  I plan on taking the test in the next week or so if I can find a place, but in the meantime, I had been looking for affordable radios. 

I found a pretty good deal on a Yaesu FT-847 and decided to pull the trigger.  As it turns out, it shipped in sooner than expected, and now I'm a bit unsure how I can test it out to make sure it's in working order.  I figure the best thing I can do is wait until I have my license and call-sign in-hand before I can test any of the transmitter functions, but in the meantime, I had some questions:

  • Are there any gotchas to plugging it in and testing it out in terms of receive-only?  I already discovered from the manual that the "MOX" switch toggles on the transmitter, and it was shipped to me switched on... glad I caught that.
  • Is it okay to test anything to do with transmitting with a 100W dummy load connected through a LMR-400 coax feedline?  I imagine everything leaks RF at least a little, somewhere.
  • What about tuning an antenna to dial-in SWR?  Tuning has to transmit something, so my hunch is that this strictly requires a license.
Sorry if these are newbie questions.  I just have a window of time where I can do returns on the Yaesu, and at the same time don't want to do anything unlawful, so I want to do as much testing as I can given my current limitations.

Any suggestions are much appreciated.
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KU4UV

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Re: Questions about transceiver testing before license
« Reply #1 on: October 19, 2022, 06:17:43 PM »

Nothing at all wrong with simply using the radio to listen to received signals.  You don't need a license for that.  I would test the radio transmitter using the 100 Watt dummy load and listen to the transmitter output on a second receiver if it were me.  I would use a shortwave radio if you have one, or can borrow another receiver from someone.  There is nothing wrong with transmitting into a dummy load, even without a license.  Dummy loads transform RF energy into heat energy, using a large resistor.  The larger the transmitted power output, the larger the dummy load needs to be.  Yes, every dummy load will leak a little bit of RF, but usually not enough to put a viable signal on-the-air.  I would recommend using a antenna analyzer if you want to get your antenna in a good SWR range for the band you will be operating on.  Or just wait until you get your license to test the antenna.  Good luck!

73,
Michael KU4UV
« Last Edit: October 19, 2022, 06:31:06 PM by KU4UV »
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WA9AFM

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Re: Questions about transceiver testing before license
« Reply #2 on: October 19, 2022, 06:53:26 PM »

Contact a local amateur radio club and explain you situation.  I warrant you'll have plenty of offers to give the 847 an 'on the air test'.  Good choice of radio, by the way.
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VK3KTO

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Re: Questions about transceiver testing before license
« Reply #3 on: October 19, 2022, 07:51:38 PM »

Enjoy the FT847, I have used one for well over 20 years without any trouble at all. Don't listen to people who say they are not so good on HF. I find that my FTDX1200 is more selective, but that's about all.        As a matter of interest, before the second war in England there was what they called an "Artificial Arial License" It was amazing just how far some would  radiate, if you know what I mean!
Good luck with license. 73 de Mike VK3KTO     
     
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KF4HR

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Re: Questions about transceiver testing before license
« Reply #4 on: October 19, 2022, 08:04:30 PM »

You can still generate a local cloud of RF energy when transmitting into a dummy load, even when using a high end dummy load, such as Bird.  The wise thing to do is wait to transmit until you are licensed.  If you feel the need to test the transmitter, find a properly licensed ham, let them test the transmitter for you.

Butch, KF4HR
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K9RJ

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Re: Questions about transceiver testing before license
« Reply #5 on: October 19, 2022, 08:53:21 PM »

I am impressed by your thoughtfulness. It's a good sign that you will be a great ham radio operator. Keep studying while you are in the groove and target getting the next level exam passed by a date you select.
Harris K9RJ Sandy, Utah, licensed since 1967.
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G4AON

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Re: Questions about transceiver testing before license
« Reply #6 on: October 20, 2022, 12:25:31 AM »

You can still generate a local cloud of RF energy when transmitting into a dummy load, even when using a high end dummy load, such as Bird.
The signal will radiate only a very short distance, perhaps no further than your property boundary. How do you think workshops test and align radio equipment? The repair techs won’t all have a license to transmit.

Many amateurs don’t even possess a dummy load, well done on getting one.

Another useful item of test equipment is an antenna analyser, I have both a Rigexpert AA-230 Zoom and a NanoVNA. Both measure SWR, the 230 is more “handy” to use outdoors and is more rugged than the Nano, you can display the SWR on 5 frequencies simultaneously, which can be useful when adjusting multi band antennas. The Nano is very low cost for something that covers up to 1.5 GHz, or in some cases higher. They can appear complicated, but at a basic level they will measure SWR, if that is all you want to measure. Beware the NanoVNA is rather delicate and uses SMA connectors.

73 Dave
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W4FID

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Re: Questions about transceiver testing before license
« Reply #7 on: October 20, 2022, 03:15:41 AM »

GREAT THAT YO'RE ASKING ALL THE RIGHT QUESTIONS AND WANT TO DO IT RIGHT. WELCOME ABOARD. I have had FT8 QSOs up to a few miles away while using a high quality dummy load and about 6 feet of coax between it and the rig. So, yes, you are radiating some and without a license that's not legal. True, FT8 is a weak signal mode, and 2 or 3 or 4 miles is not a lot, so it's unlikely you will get caught. But getting someone to help you has three major benefits. First it's legal. Second you'll get a real test by someone who knows what to look for so you'll have better evaluation of the rig. Third you're less likely to fry something -- there is a learning curve he has that you don't have yet.
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LINEAR

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Re: Questions about transceiver testing before license
« Reply #8 on: October 20, 2022, 04:41:20 AM »

Hey guys,

Thanks for all your suggestions!  Your suggestions to take it to a local club is brilliant.  I think that's definitely the best call here, considering that someone there will know much more about the radio's functions than I will.  I might test receive functionality on my own before then, once I'm done reading the manual.  Already got my power supply and checked that it outputs proper voltage, just waiting on the antenna to ship in. 

I should have probably bought an antenna analyzer first thing instead of an SWR meter, considering antenna analyzers have SWR meters built-in.  Ah well, my budget for the month is a bit negative at the moment, so I'll have to give it a bit.

As for testing on the dummy load with a second receiver, I do have a Baofeng for that, so at least I'd be able to test the VHF/UHF, but I think I'm going to go with the "take it to a local club" option.
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KD6VXI

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Re: Questions about transceiver testing before license
« Reply #9 on: October 20, 2022, 08:20:56 AM »

I don't think the feds are going to come knocking on your door for incidental radiation from a dummy load.

But, incidental radiation is a real thing.  There is (was) a ham in Oregon that swapped out a light bulb for his antenna on a fairly largish tower.

He was able to make contacts with it.  Hundreds and hundreds of contacts.

If you're really worried about it, use a common mode choke at the dummy load.  This removes incidental radiation from common mode currents.  Which, when you think about it, are full strength, since the shield is the ground return for the dummy load.

But seriously.  You won't get in trouble for turning the radio on.  You won't get in trouble for listening.  Just don't plug a mic into it, problem solved.


I honestly wouldn't worry about it. 


--Shane
WP2ASS / ex KD6VXI
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K4EQ

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Re: Questions about transceiver testing before license
« Reply #10 on: October 20, 2022, 09:01:09 AM »

I respectively take issue with those who say it is permissible to transmit into a dummy load without a license. The dummy load is still an antenna. I have made a half dozen contacts with stations a few blocks away using one. As a Novice in 1960, I did a ham radio demonstration in one of my 8th grade classes. I had a prearranged contact with a ham several blocks from the school. My station was a Heath DX-20 transmitter and a Heath AR-3 receiver. My Antenna for the DX-20? A 100-watt lightbulb.

Dale K4EQ
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W9IQ

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Re: Questions about transceiver testing before license
« Reply #11 on: October 20, 2022, 10:36:25 AM »

I respectively take issue with those who say it is permissible to transmit into a dummy load without a license. The dummy load is still an antenna. I have made a half dozen contacts with stations a few blocks away using one. As a Novice in 1960, I did a ham radio demonstration in one of my 8th grade classes. I had a prearranged contact with a ham several blocks from the school. My station was a Heath DX-20 transmitter and a Heath AR-3 receiver. My Antenna for the DX-20? A 100-watt lightbulb.

Dale K4EQ

You may find it interesting that Part 15 allows you to operate without a license in the HF ham bands but with specific field strength limits:

  • 1.705-10 MHz you may not exceed 100 microvolts/meter at a distance of 30 meters.
  • For the remainder of the HF ham bands up to 30 MHz you may not exceed 30 microvolts/meter at a distance of 30 meters.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

K0UA

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Re: Questions about transceiver testing before license
« Reply #12 on: October 21, 2022, 07:58:05 AM »

I respectively take issue with those who say it is permissible to transmit into a dummy load without a license. The dummy load is still an antenna. I have made a half dozen contacts with stations a few blocks away using one. As a Novice in 1960, I did a ham radio demonstration in one of my 8th grade classes. I had a prearranged contact with a ham several blocks from the school. My station was a Heath DX-20 transmitter and a Heath AR-3 receiver. My Antenna for the DX-20? A 100-watt lightbulb.

Dale K4EQ

But a 100 watt lightbulb is a much more efficient radiator than a good dummy load. FT8 contacts have been made on lightbulbs for hundreds or even thousands of miles.  What I am saying is a lightbulb is a VERY poor dummy load. Because it radiates so well. Sure "good" dummy loads radiate some too, but no where near as well as a light bulb.
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73  James K0UA

LINEAR

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Re: Questions about transceiver testing before license
« Reply #13 on: October 21, 2022, 11:33:07 AM »

But a 100 watt lightbulb is a much more efficient radiator than a good dummy load. FT8 contacts have been made on lightbulbs for hundreds or even thousands of miles.  What I am saying is a lightbulb is a VERY poor dummy load. Because it radiates so well. Sure "good" dummy loads radiate some too, but no where near as well as a light bulb.

Just as a thought experiment, would putting a dummy load in the microwave reduce how far it radiates?  I mean, you wouldn't be able to close the door all the way with the feed line in the way, but more or less, isn't a microwave oven pretty well shielded?  Of course, the feed line and transceiver themselves would leak anyway.


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K0UA

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Re: Questions about transceiver testing before license
« Reply #14 on: October 21, 2022, 04:30:25 PM »

But a 100 watt lightbulb is a much more efficient radiator than a good dummy load. FT8 contacts have been made on lightbulbs for hundreds or even thousands of miles.  What I am saying is a lightbulb is a VERY poor dummy load. Because it radiates so well. Sure "good" dummy loads radiate some too, but no where near as well as a light bulb.

Just as a thought experiment, would putting a dummy load in the microwave reduce how far it radiates?  I mean, you wouldn't be able to close the door all the way with the feed line in the way, but more or less, isn't a microwave oven pretty well shielded?  Of course, the feed line and transceiver themselves would leak anyway.

I don't think I would stick it into the microwave. But a metal 5 gallon bucket with a metal lid with a hole in it just big enough to pass the coax connector would probably offer a bit more RF shielding once you closed the lid and fastened it down good.
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73  James K0UA
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