Technical Topics > Equipment
MLA-30 Loop antenna
~SIGINT~:
--- Quote ---today the average home is a cesspool of RFI/QRM generators
--- End quote ---
I concur with that comment. I have been hunting down a strange pulsing / data RFI since I moved in to this home 6 months ago and stumbled across it by accident yesterday. Unexpectedly, it is the HVAC control module and user console chatting away. This was completely unexpected but a google search revealed that this is not uncommon. Now I have to figure out how to filter this bad boy.
One of the easiest ways to find some of this RFI/EMI is by using an Inductive Amplifier such as the one found in the 200EP Inductive Amplifier Line Finder Cable Tester Portable Tone Generator Kit. The kits or the inductive amplifier are abundant on Amazon and eBay and are relatively inexpensive. This is how I stumbled upon the noisy HVAC system yesterday by locating and tracing abandoned cables in the basement ceiling.
Here is what a kit looks like (and the industry acronym for it is a "fox and hound":
Progressive 200EP Inductive Amplifier 77HP
Ray Lalleu:
--- Quote from: ~SIGINT~ on January 04, 2023, 1442 UTC ---
--- Quote ---today the average home is a cesspool of RFI/QRM generators
--- End quote ---
I concur with that comment. I have been hunting down a strange pulsing / data RFI since I moved in to this home 6 months ago and stumbled across it by accident yesterday. Unexpectedly, it is the HVAC control module and user console chatting away. This was completely unexpected but a google search revealed that this is not uncommon. Now I have to figure out how to filter this bad boy.
One of the easiest ways to find some of this RFI/EMI is by using an Inductive Amplifier such as the one found in the 200EP Inductive Amplifier Line Finder Cable Tester Portable Tone Generator Kit. The kits or the inductive amplifier are abundant on Amazon and eBay and are relatively inexpensive. This is how I stumbled upon the noisy HVAC system yesterday by locating and tracing abandoned cables in the basement ceiling.
Here is what a kit looks like (and the industry acronym for it is a "fox and hound":
Progressive 200EP Inductive Amplifier 77HP
--- End quote ---
That site does not specify to what frequencies that tester is sensible.
I'm just using an old small Sony radio !
~SIGINT~:
--- Quote ---That site does not specify to what frequencies that tester is sensible.
--- End quote ---
It is only as good as the speaker that is in the unit and your hearing --- audio frequency range. The key is if it is leaking out of the cable or device, it is leaking into the antenna. I also use my HP/Agilent spectrum analyzer or ICOM IC-705 with a magnetic sensing loop but not everyone can afford that. You can easily find dirty wall warts, LED / fluorescent lights etc ... with the inductive amplifier probe. A used one will only set you back about $20.00. Have to start somewhere.
RobRich:
The tinySA is neat gadget for those wanting a basic SA but not needing a lab-grade spectrum analyzer.
https://www.tinysa.org/wiki/
https://tinysa.org/wiki/pmwiki.php?n=Main.Buying
I have the original model, though there are now models with larger screens, higher frequencies, and whatever other options.... for more money, of course. ;)
Teotwaki:
I bought a Chinese MLA-30+ and modified it a little. I desoldered most of the DC-DC converter in the bias T and ran in a line from a 12.6vdc linear supply. I tossed the thin stainless steel loop wire too. I took some aluminum jacketed 1/2" coax and made a loop. I squashed the jacket flat on each end, bent a 90 degree tab and drilled it. It seems to be about 2.9 uH
The antenna's output is run through a Navy surplus multicoupler that has a great 2 - 32 MHz preselector filter before the amplifiers.
Despite all of the MLA's engineering flaws in the amplifier design it performs fine mounted up high, outdoors when compared to an untuned 70' end fed wire. That leads me to believe a correctly designed active loop could perform even better.
The DW beacon
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version