Magnetic Loop Amplifier
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- Опубликовано: 1 окт 2024
- The untuned loop is a real winner, but it suffers from low sensitivity. Let's build a remote loop amplifier that brings its performance up. First we need a bias tee for the shack and receiver side.
Not 47 uHY, it is a 470 uHY. This misinterpretation would be avoided by using an inductance meter and a reactance chart to find the impedance. The markings on the chokes unfortunately vary by manufacturer.
I AM FROM BRAZIL!!! THANK YOU FOR THIS PROJECT!!! I WILL ASSEMBLE THIS BROADBAND TRANSISTOR AMPLIFIER !!!! THIS DEVICE WILL BE IN MY HOMEBREW SHORT WAVE RECEIVER!!!73!!!
Good luck on your project. For shortwave, I would stick to a single loop of 1 to 2 meters diameter.
is the the circuit by Chavdar Levkov LZ1AQ
Yes and quite fancy!
You said. "we" at Nearfest but I only saw you.
I was with another ham buddy WA1QHQ. He walked around a lot!
I prefer the term "penurious" - fools the ignorant and sounds way classier than "cheap" ;>). Looking forward to seeing the rest of this loop amplifier series. Also would like to see you build a 100 watt transmitting loop as that's about the only type ham antenna I have space for. Thanks!
Wow! Even better.
Thank you for sharing your knowledge! 73, Bret/AC0AE
I loved the painting of a picture in my mind of the woods and on and a island sending and sos
Yes with Marianne or Ginger?
@@MIKROWAVE1 I spent so much time with em I can’t do another second I’m leaving them here
In my garden, I grew some germaniums!
Did they smell?
Looking forward to this, thanks for your efforts making these videos. I have a cheap MLA-30 loop off amazon now just to get listening. But I've decided I'll keep some sort of untuned loop for receive only on the SDR when I build a transmitting loop too have a wideband view so to speak. Been doing lots of research on transmitting loops and have a few ideas on construction. Between the 'garden warmer' crowd and other random misinformation, it's been challenging to research. Then throw in the confusion on multiturn loops, it's turned into a good subject to think about when I want to be asleep.
One thing that I don't understand is I've found a couple people state that ribbon type conductors are not good for transmitting mag loops. Seems like an easier way to mitigate skin effect, and didn't really understand the argument against. But I can't find that reference now. Any thoughts on that?
An oversized version of litz wire like 100 or so insulated solid # 20 conductors would have to provide some Q advantage over a pipe of the same diameter. I have never built the more popular compact transmitting loop, so no experience. But lots in the literature and on line. All of them work - to some extent that usually amazes the builder.
@@MIKROWAVE1 that's the line of thinking I've been going down. I know litz wire isn't good up to the needed frequencies. But something like ide cable sounds interesting. Of course if a ribbon doesn't work out well, then ide cable would be hard to form into a bent tube. I've thought of trying to 3d print torrid sections with a number the channels for wires. Some real technical issues with the software for this part.
I have no trees, and putting up a tower isn't an option, so mag loop experimentation it is then.
Do some reading on "antenna aperture" to understand better why loop antennas are not very effective for transmitting. (the loop would need to be 1/4 wave on a side!) HUGE!
@@glasslinger I've never seen you out 'in the wild' so to speak, thanks. I was not really familiar with the term, but had caught on to the concept. I'm pretty much stuck with the mag loop antenna for the foreseeable future due to situation. Since a mag loop works better the higher the current built up in the loop, is that due to the magnetic field being larger and increasing its aperture size? I'm new to RF stuff BTW.
I've got enough time in research and design at this point I'm going to build one regardless. Thanks for the input, take care and we need to get you tooled up for full production. Seems to be a shortage of some tubes these days! lol
Antenna season 🤣
You are perfectly right !
I use a Texas LM317T 1.5 amp voltage regulator which is adjustable from 1.3 to 37 volts with max voltage in put of 40 volts the input voltage must be 3 volts above the regulated voltage at max current, ( lower input can be tolerated at lower current draw) so a lower input voltage can be used. A 15v output ac secondary transformer would be ideal for this project after smoothing cap added its about 21volts. under load a bit less
Not much happens when you fall below regulation with a constant load like this. So it all works out even if you mess up and have too low a source voltage.
Great video Mike! I've always wanted to ask you are you an electrical engineer? You're so knowledgeable and I have always learned a ton from you. I'm also a ham radio operator and I've learned electronics over the years but I don't have a quarter of the knowledge you do that's why I figure you're probably an EE?
Worked in EE roles, but not a proper EE. Always lacked the math and discipline. More like a cross between a tech and an EE.
@@MIKROWAVE1 That's extremely relatable!
The best amplifier chip for a Loop antenna chip is the MC1350 and you can still use a Ethernet cable to connect the headend to the power interface.
Ah the good old 1350. The LM386 of the RF world!
Howdy.
What fertilzer did you use to get transistors to grow ? I tried my cat's litter but that only made 12AX7 tubes pop up.
Regards.
Thanks for watching, and 12AX7s are a good crop all right!
@@MIKROWAVE1 Maybe they grow better in rare earth?
Mike,
How about natural series resonance in the choke of your bias Tee?
A real issue at higher frequencies! A true broadband choke is indeed a difficult problem with a simple choke (or a single choke).
thanks a lot! it's useful!
Very interesting
Delighted to be the first viewer!