Two points: 1) Loop antennas develop dangerously high RF voltage at the coupling when transmitting. Contact could be lethal with 100 watts of input. That may be one benefit of MFJ’s ugly enclosure to keep out moisture. Point 2) There’s plenty of room inside the Chameleon tuning box for a taller butterfly cap with wider spaced plates. That would eliminate arching and allow higher feed power. However, Chameleon my intend to force limited input power to save lives & lawsuits. Side note: I’ve built and used commercial transmitting loops for years. One ham surmounted the extremely high Q limitation by flattening the small feed loop into an oval shape on the loop antenna he built. More coupling widened the Q of his antenna from a few kHz to greater than 20 kHz. He published all his test results. I purchased my best performing 40-meter loop used from another ham. Both the feed loop and larger transmitting loop are square. In this case, there is nothing magical about a circle. 73, Pat, W6ABA
Hi Dave,I've got a Capco AMA 3 which I use regularly mounted outside on a rotator approx 8ft off the floor and usuable on 20, 17, 15 and 10 and for an antenna that's over 20 years old it works really well.It's had the capacitor drive motor changed and upgraded but apart from that it's original.I'm also going to be trying out a fractal loop soon, that should be interesting.I watched your videos on the MFJ loops and saw that the build quality, as with some of there other equipment and I have several of their items, was not that great considering the price they cost. I think the QC really does need looking at, very good design, but let down by the finished article!Keep your videos coming73 Geoff M0CRO
Dave, I listened on Saturday near Philadelphia, but heard nothing. Chameleon makes the RT-RR remote tuner remote rotator for the F loop. I'm surprised they have not adapted it for the P loop. 73 WB3BJU
Donald D'Egidio: they do have the RT-RR. However, the type of operation this is gear toward is the field setup with less weight and minimal things to carry. So if you need a remote you should use the P-loop. 73
Perhaps a better option to fight home based QRM is to use a dedicated listening loop such as a wellbrook with a rotator and TX using wire end fed or dipole? Use a relay switch or rig with 2 antenna inputs or a separate rig or receiver for rx.
I'm curious, Dave. The circumference of the Earth is 24, 901 miles, so the farthest apart two locations can be on the surface is 12,450 miles. Was that ZL station perhaps 17-thousand kilometers away, not miles? Second question: Do I win a prize? ; ^ ) Just rattling your cage. Your videos are consistently excellent!
Outstanding questions that I don't know the answers to! It's clear it puts RF reactance in the system, but from what little I've been able to read about power compensators, they aren't necessarily linear. If you run across a good explanation, let me know!
They measure the energy in and out of my radio room relative to the bigger photovoltaic system in the basement. The first meter gives the system voltage. It's an expanded-range voltmeter that I cobbled together with a zener diode and some resistors. It's accurate to about a tenth of a volt. The meter on the right is an ammeter that measures the current coming from the main PV system to charge the local 12v battery under the desk. 73!
Hi Dave, really enjoy your videos. i was wondering, following up on your MFJ 1788 review if you could do a follow up on a typical apartment installation with respect to grounding etc. I've recently purchased a 1788 for my condo, but I'm at a loss as to how to ground the control box and my transceiver for that matter. By the way, I'm sorry the issues you had with your web site and I'm glad they've been resolved. Best regards, VE3WNS/M0CEL
Dave I just got my Ham License Technician Class, What VHF and VHF bands can I use ? Could you do a UA-cam Video Just for me on that and yes the test was Hard and I'm going for the General License Victor LOL
Yeah, Saturday was tough. I listened, heard nothing. I think that the next logical step for these loops is not only remote tuning, but remote automatic tuning. For such a high q system, the constant manual retuning will keep this from becoming a mainstream antenna style. But make it a remote auto tuner, things get more interesting.
Two points: 1) Loop antennas develop dangerously high RF voltage at the coupling when transmitting. Contact could be lethal with 100 watts of input. That may be one benefit of MFJ’s ugly enclosure to keep out moisture. Point 2) There’s plenty of room inside the Chameleon tuning box for a taller butterfly cap with wider spaced plates. That would eliminate arching and allow higher feed power. However, Chameleon my intend to force limited input power to save lives & lawsuits.
Side note: I’ve built and used commercial transmitting loops for years. One ham surmounted the extremely high Q limitation by flattening the small feed loop into an oval shape on the loop antenna he built. More coupling widened the Q of his antenna from a few kHz to greater than 20 kHz. He published all his test results.
I purchased my best performing 40-meter loop used from another ham. Both the feed loop and larger transmitting loop are square. In this case, there is nothing magical about a circle.
73, Pat, W6ABA
This was an absolute fabulous review. Thanks Dave.
Very good review Dave! I liked the comparison between the P-Loop and the MFJ-1788, both antennas I have been curious about.
Hi Dave,I've got a Capco AMA 3 which I use regularly mounted outside on a rotator approx 8ft off the floor and usuable on 20, 17, 15 and 10 and for an antenna that's over 20 years old it works really well.It's had the capacitor drive motor changed and upgraded but apart from that it's original.I'm also going to be trying out a fractal loop soon, that should be interesting.I watched your videos on the MFJ loops and saw that the build quality, as with some of there other equipment and I have several of their items, was not that great considering the price they cost. I think the QC really does need looking at, very good design, but let down by the finished article!Keep your videos coming73 Geoff M0CRO
Dave,
I listened on Saturday near Philadelphia, but heard nothing. Chameleon makes the RT-RR remote tuner remote rotator for the F loop. I'm surprised they have not adapted it for the P loop. 73 WB3BJU
Donald D'Egidio: they do have the RT-RR. However, the type of operation this is gear toward is the field setup with less weight and minimal things to carry. So if you need a remote you should use the P-loop.
73
Perhaps a better option to fight home based QRM is to use a dedicated listening loop such as a wellbrook with a rotator and TX using wire end fed or dipole? Use a relay switch or rig with 2 antenna inputs or a separate rig or receiver for rx.
I'm curious, Dave. The circumference of the Earth is 24, 901 miles, so the farthest apart two locations can be on the surface is 12,450 miles. Was that ZL station perhaps 17-thousand kilometers away, not miles?
Second question: Do I win a prize? ; ^ ) Just rattling your cage. Your videos are consistently excellent!
Thanks Dave!
How does the power compensator work? What is it made of?
Outstanding questions that I don't know the answers to! It's clear it puts RF reactance in the system, but from what little I've been able to read about power compensators, they aren't necessarily linear. If you run across a good explanation, let me know!
@@davecasler I'd love to see someone cut one of them open :)
Hi dave quick question. What the two meter gauges over the the "73" sticker on your desk?
They measure the energy in and out of my radio room relative to the bigger photovoltaic system in the basement. The first meter gives the system voltage. It's an expanded-range voltmeter that I cobbled together with a zener diode and some resistors. It's accurate to about a tenth of a volt. The meter on the right is an ammeter that measures the current coming from the main PV system to charge the local 12v battery under the desk. 73!
Hi Dave, really enjoy your videos. i was wondering, following up on your MFJ 1788 review if you could do a follow up on a typical apartment installation with respect to grounding etc. I've recently purchased a 1788 for my condo, but I'm at a loss as to how to ground the control box and my transceiver for that matter. By the way, I'm sorry the issues you had with your web site and I'm glad they've been resolved. Best regards, VE3WNS/M0CEL
I think the thing to do is just try it. It may well be that you won't have RFI issues, or if you do, sometimes merely moving things around can help.
Well Done Dave.
73 de oh8stn
OH8STN YOUR review is why I’m here watching Dave’s review! Probably going to pick up this antenna for QRP field/travel use...thanks to you too!
try looking at the MFJ 936B for a portable mag loop and a tape measure
Dave I just got my Ham License Technician Class, What VHF and VHF bands can I use ? Could you do a UA-cam Video Just for me on that and yes the test was Hard and I'm going for the General License Victor LOL
Hmm...I thought I'd done such a video, but looks like I haven't. I'll add a VHF/UHF tour to my topic list.
2meter 70 cms?
And yes I did watch your older Videos Before I took the test
Yeah, Saturday was tough. I listened, heard nothing.
I think that the next logical step for these loops is not only remote tuning, but remote automatic tuning. For such a high q system, the constant manual retuning will keep this from becoming a mainstream antenna style. But make it a remote auto tuner, things get more interesting.
The autotuner would definitely make magnetic loops much more attractive!
This Loops are Perfect for Hams Who lives in Apartments in Large Cities like New York City!
Sorry I could not hear you in the springs. Look forward to another try soon. 73 W1NGA
is that a bc348 in the back ground.
It's an old Hallicrafters S-20R.
This antenna looks like an Alexloop antenna copy. I have had good QSOs with my Alexloop at 10w.
The designs for these loops are pretty standard. It's hard to say who's copying whom! Loops have suddenly become fashionable.
I suggest giving lots of notice for the next on air assist. Maybe plan a on-air Meetup. 73
Yes, that sounds like a good idea!
Thanks Dave Yes a Video would be Nice on What VHF and UHF Frequencies I can Use as Technician Aloha from Hawaii the 50th State !!!
The ARRL has a frequency chart that shows all entitlements by band and class of license.
File carefully but not lightly. Got it.
I'm sorry, but this seems terribly overpriced to me. I'm building something very similar with a better capacitor for under $100.