Best low EMF shortwave radio for a beginner? - Page 1
Forum section: electronics / beginners

author: nethawk
author_rank: Newbie
timestamp: June 15, 2023, 06:23:06 pm
content: Greetings all. New here and very happy to have found the forum. Crazy title, I know, but I'm a former techie who developped severe electrical hypersensitivity due to overcomputing (developing game mods and videos for customers - computer was always on day and night with wi-fi enabled). Anyhow, I purchased last year a Techsun 380 and although it worked great I couldn't be around it for more than ten minutes as it had a strong EMF field and my electrical hypersentivity flared up (checked with our gaussmeter). So I then purchased a cheap Borne shortwave radio although the EMF was low it stopped working a month later. So...what is a good, reliable SW radio with good receptivity AND low EMF ratings? I suspect any model NOT having any sort of electronic or computer chip inside. My needs: keeping up to date via SW on world events, decent FM and AM. That's about it. I'd LOVE VHF and SSB receptivity as well as NOAA, but I suspect the EMFs will skyrocket if the radio comes with those features. Oh - and nothing requiring more than 3 AA batteries would be sweet too. Anyhow, thanks for the answers.

author: xrunner
author_rank: Super Contributor
timestamp: June 15, 2023, 06:36:24 pm
content: Quote from: nethawk on June 15, 2023, 06:23:06 pmI don't know of any shortwave receivers that have published EMF ratings so how could anyone advise you? If you can't have microcontrollers inside you need to look at old school receivers from the '70s and earlier. Even radios from the '80's will have logic chips inside doing their thing ...

author: TimFox
author_rank: Super Contributor
timestamp: June 15, 2023, 06:56:39 pm
content: An antique solution: the E H Scott SLRM short-wave receiver designed for the merchant marine in WW II.https://ehscott.ning.com/profiles/blogs/scott-slrm-national-radio-r-302-ure-22-connectionThere are no digital devices at all, and a design requirement was serious shielding to prevent local-oscillator radiation from the antenna that could be found by U-boat direction finders.To that end, the input RF amplifier uses a 6K7 double-ended (with grid cap) pentode, although the IF amplifiers use single-ended 6SK7s.A wartime advertisement:https://www.periodpaper.com/products/1942-ad-scott-marine-model-radio-submarine-low-radiation-receiver-world-war-ii-106202-fz4-199A similar unit's manual:https://frank.pocnet.net/instruments/EHScott/RCH/Scott_RCH_manual.pdf

author: Xena E
author_rank: Frequent Contributor
timestamp: June 15, 2023, 07:33:03 pm
content: Could the OP or someone explain the acronym EMF in the context of this thread?

author: radiolistener
author_rank: Super Contributor
timestamp: June 15, 2023, 10:29:53 pm
content: probably topic starter talking about EMI (ElectroMagnetic Interference) when he saying EMF (ElectroMotive Force)Some radio receivers, especially digital one, can have parasitic EMI from their LCD, CPU, FPGA or oscillators. These EMI prevents these radio to listen very weak stations. In other words, these EMI reduce sensitivity of these receivers.If you want ultra low EMI, you can try to use full analog radio, it's EMI is almost zero, but it still may have strong EMI from oscillators.

author: TimFox
author_rank: Super Contributor
timestamp: June 15, 2023, 10:35:41 pm
content: He probably means "electromagnetic field", claiming that he is sensitive to it.Electromagnetic interference, that we used to call RFI, is a matter of other equipment's sensitivity.

author: CaptDon
author_rank: Super Contributor
timestamp: June 15, 2023, 10:44:58 pm
content: Kind of seems more like a troll? Electromagnetic Hypersensitivity?? Did you rip out all of the A.C. wiring in your house yet? That probably radiates more than any quality SW radio. If the radio did radiate it wouldn't be much of a radio. How about an old Kenwood R1000 or R2000? there is no way they radiate more than a few microwatts of anything. Metal case, etc., Don't tell me you are too sensitive to be around them. Overexposure to computers has made you hypersensative? Holy crap, how many of us on this forum have spent a 40+ year career around transmitters and antenna fields that would light a flourescent lamp in your bare hands? My quick test on malfunctioning radars to determine transmitter or receiver failure was to hold a dead nixie tube in front of the antenna and see if it glows. I seriously doubt anyone can be that 'hyper-sensitive' to EMI/EMF when we are talking less than a couple of milliwatts of radiated energy that diminished to nothing at three feet of distance.

author: TimFox
author_rank: Super Contributor
timestamp: June 15, 2023, 10:59:47 pm
content: The nice thing about household AC wiring is that the two conductors are very close together, and the AC magnetic field falls off very quickly with distance.Electric blankets can produce a substantial field, but they're not very popular anymore.Maybe you can get fields from a hair dryer or toaster due to the conductor geometry.

author: radiolistener
author_rank: Super Contributor
timestamp: June 15, 2023, 11:17:26 pm
content: Quote from: CaptDon on June 15, 2023, 10:44:58 pmI think he is talking about issue when receiver suffers from RFI from nearby electronic devices. Probably this is what he means when talking about "hyper sensitivity".But this issue cannot be solved just by replace receiver with more quality one. It also requires other measures, include using proper external antenna, using RF chokes on the antenna cable and remove cheap Chinese SMPS devices from home, such as LED bulbs and other

author: TimFox
author_rank: Super Contributor
timestamp: June 15, 2023, 11:26:12 pm
content: From the OP: "I couldn't be around it for more than ten minutes as it had a strong EMF field  and my electrical hypersentivity flared up"

author: Infraviolet
author_rank: Super Contributor
timestamp: June 16, 2023, 06:08:26 pm
content: "I couldn't be around it for more than ten minutes as it had a strong EMF field  and my electrical hypersentivity flared up"An honest suggestion for the OP, try some randomised controlled trials. Have someone else control whether electrical devices are active or not, without you knowing which state the things are in. Also have them set up some "dummy" devices, such as a wi-fi router which blinks its LEDs but has antennas disconnected so cannot produce actual radio transmissions. Have them see if your symptoms really do happen only when genuine emissions are in your presence, regardless of your awareness of them. If you find it is your awareness of operating devices, and not their actual presence, that matters in terms of symptoms, then you have a psychosomatic condition (quite common across various forms). Your best option might be to seek medical help for typical psychosomatic conditions, and to cover up LED and other activity inicators on devices (your mind might know intellectually that they're still running, but without the imemdiate visual clue the subconsious cause of psychosomatic conditions might not react to them).

author: nethawk
author_rank: Newbie
timestamp: June 17, 2023, 12:14:38 am
content: I am anything but a troll, Electrical hypersensitivity is real, EMF stands for Electrical magnetic fields, and...thanks to some replies given, I will take the advice and go old school for a manual receiver with a turning knob. ArrivaderciIF it interests some, here is ONE of many credible sites on the topic. It is a growing phenomenon.https://pubmed.ncbi.nlm.nih.gov/32289567/

author: CaptDon
author_rank: Super Contributor
timestamp: June 17, 2023, 01:15:46 am
content: InfraViolet, you are right on the money with your statement. I thought the same thing exactly. We need some devices that are audibly silent when powered on or off. And a blind test with blindfolds and earmuffs. Then, over a 4 hour period we randomly or not energize various devices for 15 minute intervals and look for a measurable response, resparation rate, heart rate etc. and look for demonstrated correlation. I doubt if the valid hits reach even 25%. I see pidgeons with the iron in their brain which allows them to track the earth's one gauss magnetic field sitting on 13.2Kv lines which surely have one hell of an EMF/EMI field and they don't seem affected. I never met one with an Excederine Headache anyway. A digital readout may produce EMI in the extreme near field like resting on your forehead, but in only 1 metre where are we, a couple microvolts per meter and a few milli-gauss? Geez, take the magnetometer off the tail of the P3C Orion aircraft and use this dude for Anti Submarine Warfare detecting magnetic disturbances under the sea/ocean/ice cap. I can locate a line frequency power transformer likely location within a device using a microphone and cranking the gain and looking for the magnetic field leakage inducing voltage into the microphone dynamic coil but again, we are looking at milli-gauss. If he really is that sensative to EMF he has a rewarding career as a scientific 'detector' or perhaps on the ghost hunter show.I am still a Doubting Thomas however. Stay clear of Aurora Borealis and Solar Flares!!

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 17, 2023, 01:35:46 am
content: Hallucrafter S-38. Adequate, but not great performance. Excellent reliability. Some are still working after 80 years. Unfortunately no FM.

author: BrokenYugo
author_rank: Super Contributor
timestamp: June 17, 2023, 04:05:56 am
content: Crystal set is self powered, can't beat that.https://youtu.be/u1vK3QcyBBw

author: radiolistener
author_rank: Super Contributor
timestamp: June 17, 2023, 04:50:22 am
content: You can fix RFI issue of receiver by using external antenna, it should be placed far away from the building and mains wires. Use coax cable with RF-chokes on it to delivery signal into your receiver.You can use active magnetic loop antenna.Some examples can be found here:https://pa0fri.home.xs4all.nl/Ant/PA0FRI's%20actieve%20antenne/PA0FRI's%20active%20loop%20antenna.htm

author: Xena E
author_rank: Frequent Contributor
timestamp: June 17, 2023, 06:19:54 am
content: Quote from: nethawk on June 17, 2023, 12:14:38 amCrackpot then?Quote from: nethawk on June 17, 2023, 12:14:38 amDamn straight it is sweetie! (If you touch it...) pity the poor sufferer who has to also undergo medical Magnetic Resonance Imaging....that must really fuck them up....Quote from: nethawk on June 17, 2023, 12:14:38 amNot a classic use of the acronym. You should have referenced that in your OP.Quote from: nethawk on June 17, 2023, 12:14:38 amOf course it's a growing phenomenon, monkey see monkey do....My suggestion:Buy a tent, live in the woods...

author: CaptDon
author_rank: Super Contributor
timestamp: June 17, 2023, 02:05:28 pm
content: Hallicrafters made some great beginner radios and some nice upscale stuff. Dad had an S-20R I believe and I also had perhaps an S-38. I modded mine with a line isolation transformer so I could get direct antenna coupling and reduce the ground loop audio hum. I could receive the 15.770Mhz 15Kw Icelandic broadcast while living in central Pennsylvania! Loved my old National NC-300 also!!! Used it with my novice CW-only license.

author: coppercone2
author_rank: Super Contributor
timestamp: June 17, 2023, 02:52:29 pm
content: you could probobly make something with like bicycle break lines or monofilament plastic to adjust a radio and monitor it through a scope

author: Infraviolet
author_rank: Super Contributor
timestamp: June 17, 2023, 03:34:02 pm
content: Acronyms, what fun. EMF has become much more used in the general public to refer to ElectroMagnetic Fields, rather than the ElectroMotive Force use found in circuit theory. I expect >90% of the public would only be aware of the fields meaning.P.S. If the OP's problem is genuine he might look it to whether he is just really sensitive to the shrill audio whine some switching power supplies can make, especially when in stand-by modes.

author: djacobow
author_rank: Super Contributor
timestamp: June 17, 2023, 03:46:29 pm
content: You can find papers about electromagnetic hypersensitivity, and the WHO seems to recognize it, but if you dig a bit deeper you find various double blind provocation trials find that subjects cannot guess when they are being exposed any better then chance. I couldn't find one that suggested otherwise. Though I have no doubt the suffering is real, this is most likely a psychological malady.

author: TimFox
author_rank: Super Contributor
timestamp: June 17, 2023, 04:01:09 pm
content: Quote from: Infraviolet on June 17, 2023, 03:34:02 pmThe "audio whine" from switching power supplies may well be ultrasonic, and not directly audible, yet still perceptible.

author: jonpaul
author_rank: Super Contributor
timestamp: June 17, 2023, 04:10:48 pm
content: Vintage Hammarlund/Hallicrafters/Collins 1940s..1950 tube radios....Only emission is a bit of LO leakage....See ham fleas and epayJon

author: Simon
author_rank: Unknown
timestamp: June 17, 2023, 11:30:16 pm
content: When you have found your 70's radio receiver go and see a shrink!

author: Circlotron
author_rank: Super Contributor
timestamp: June 18, 2023, 12:00:42 am
content: Why not requiring more than 3 AA batteries? They generally come in packets of 4 and a charger takes 4 as well. Something doesn’t add up here…

author: vk6zgo
author_rank: Super Contributor
timestamp: June 18, 2023, 01:05:54 am
content: Quote from: nethawk on June 17, 2023, 12:14:38 amAlmost any radio receiver manufactured in the last 80 years will have at least one internal oscillator.Before that, there were Tuned Radio Frequency (TRF) radios which did not, but they were superseded by Superheterodynes, which were much easier to align accurately & having better selectivity, to use in the real world.Googling will find so-called "TRF" radios based upon a single chip, which unfortunately, have many of the disadvantages of classic TRFs, but few of the advantages.Prior to that, & for simple designs for many years later, there were Regenerative Receivers, which used positive feedback to cancel circuit losses.They could also be operated in Oscillating mode, which made it easier to receive Morse & SSB signals, so such a radio would also be a "no-no".Then there are "crystal" sets which don't use any active devices.They are not very sensitive however, & work best when you are relatively close to the transmitting station.In that case, any RF energy from your receiver is the least of your problems.In any case, the device you are using to post on this forum has oscillators in both the unit itself & the switch mode power supply, either internal, or part of its charger.There are also natural sources of Electromagnetic fields----a relatively close (several km away) lightning strike generates a much higher field strength than anything in your home.

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 18, 2023, 03:04:26 am
content: Can anyone ELI12 me how this hypersensitivity supposed to works?I can (maybe) understand if it's about working in intense field like radio transmitter, RADAR, MRI, etc. or even microwaves and inductive stoves.But spurious emission from a ham radio in (I assume) receive only? Surely a well engineered one only emit in less than milliwatt range? Your PC probably emit more than that. Mobile phone would be even worse since they need to transmit to work.

author: radiolistener
author_rank: Super Contributor
timestamp: June 18, 2023, 03:32:53 am
content: Quote from: ArdWar on June 18, 2023, 03:04:26 amyes, in some cases PC can produce more strong parasitic emission than digital receiver, but even small amount of noise may interfere with reception of very weak stations.A detector receiver (LC + simple envelope detector) doesn't have emission, but on the other hand it has very bad sensitivity and selectivityReceivers with active circuit always have some emission. Analog one has LO and BFO leakage. Digital one has wideband digital noise and a lot of parasitic carriers. But a good shielding and using RF chokes allows to minimize effect of such emissions.

author: TimFox
author_rank: Super Contributor
timestamp: June 18, 2023, 01:38:51 pm
content: Repeating a link from my earlier post, here is an example of how to shield an analog superheterodyne receiver to minimize LO leakage:https://frank.pocnet.net/instruments/EHScott/RCH/Scott_RCH_manual.pdf

author: BrokenYugo
author_rank: Super Contributor
timestamp: June 18, 2023, 02:00:36 pm
content: Quote from: ArdWar on June 18, 2023, 03:04:26 amYou're looking at this from the wrong angle. There is nothing technical to understand about what is, per any science I've seen, irrational delusional behavior. These people aren't reacting to RF, they're reacting to their own personal idea of RF and what is and is not harmful, which conveniently ignores things like the sun, the transmitter in the phone, etc.https://en.m.wikipedia.org/wiki/Electromagnetic_hypersensitivity

author: coppercone2
author_rank: Super Contributor
timestamp: June 18, 2023, 05:33:09 pm
content: well regardless I don't think you should be shoving technology to people that don't want it, once in a while they are right. there is better agendas to have that are infinitely more useful and less difficult to achievei can see RF free zones being more common in the not so near future when the sensors and stuff get good enough to let people see through walls with it though. that will be easy to prove and very unnerving due to privacy. so the low emissions technology is not a bad one to explore. like when there are cheapie rydberg systems and cheap micro cryocoolers and stuff like that

author: Infraviolet
author_rank: Super Contributor
timestamp: June 18, 2023, 08:27:29 pm
content: "Almost any radio receiver manufactured in the last 80 years will have at least one internal oscillator."Worth noting though that this local oscillator will typically be stronger and more prone to causing local radio emissions in older devices (particularly the old superheterodyne types), that is how the Gestapo and the KGB used to track down people LISTENING* to foreign radio broadcasts in the territories they oppressed. Modern receivers have a much weaker local oscillator, so we'd all be able to safely recieve radio broadcasts from abroad in any future tyranny, if there was some free contry left where they were being transmitted from with enough power to overcoming jamming. The OP is either suffering psychosomatic issues (nothing to be ashamed of) or has a problem with the barely perceptible noise of some switching supplies, but if he/she really were sensitive to electromagnetic radio frequency radition then older receivers would likely be a worse option than newer ones.*albeit at relatively close ranges

author: TimFox
author_rank: Super Contributor
timestamp: June 18, 2023, 09:12:46 pm
content: The BBC used the same procedure to locate un-licensed television receivers in the UK.Apparently, they weren't of much use.https://en.wikipedia.org/wiki/TV_detector_van#Detection_techniques

author: SpecialK
author_rank: Regular Contributor
timestamp: June 19, 2023, 01:30:11 am
content: Quote from: nethawk on June 17, 2023, 12:14:38 amSo I read your pubmed link. Authors "Yael Stein" "Iris G Udasin". Googled such. Seem to float the idea of "Electromagnetic hypersensitivity".From Wikipedia:Electromagnetic hypersensitivity (EHS) is a claimed sensitivity to electromagnetic fields, to which negative symptoms are attributed. EHS has no scientific basis and is not a recognised medical diagnosis. Claims are characterized by a "variety of non-specific symptoms, which afflicted individuals attribute to exposure to electromagnetic fields".

author: Simon
author_rank: Unknown
timestamp: June 19, 2023, 06:34:38 am
content: Quote from: coppercone2 on June 18, 2023, 05:33:09 pmOh dear, another nutter.

author: Simon
author_rank: Unknown
timestamp: June 19, 2023, 06:36:57 am
content: Quote from: SpecialK on June 19, 2023, 01:30:11 amThere is it's companion one of which I don't know the name but something to do with "chemicals" they hang the post on the line for days before opening it.Due to the way society is these days instead of telling them to stop being silly we let them carry on and "respect" their non existent rational point of view. It's all 'bout feelings, "you know, man?"

author: CaptDon
author_rank: Super Contributor
timestamp: June 19, 2023, 11:51:36 pm
content: I worked for 13 years in Commercial Radio Broadcasting. We, as the engineering team fielded some really idiotic calls from people effected by our transmitters and radio broadcasts. Claiming to hear the voices of dead relatives on their radio (why did they call us?) or not being able to sleep because of our 'radio waves' (They were 20 miles from the A.M. tower field and much closer to other stations). One said when she listens to 'our' station it causes the electric bill to be higher??? Crazies!!! Then we have some local crazies who park up on the bluff overlooking Lake Erie with their high beams on watching the sunset over the lake. I asked one of them why.....So the sun doesn't run out of energy!!!! I have gotten that reply more than once!!! Oh, and the years that I had an 18AVQ mulltiband antenna ground mounted and only used to receive SWL before I got my novice license and soon every neighbor was blaming me for interfering with their t.v. reception!!!

author: radiolistener
author_rank: Super Contributor
timestamp: June 20, 2023, 12:06:13 am
content: Quote from: CaptDon on June 19, 2023, 11:51:36 pmMany peoples just don't know that electromagnetic field strength is much more safe for health with a large antenna than with a very small one...They just thinking that since their mobile phone has a very small and hidden antenna it produce much smaller field strength than a very large antenna. This is their mistake due to a lack of knowledge... The mobile phone produces extreme high RF field strength which exceeds safety limits, while a large shortwave antenna doesn't exceed safety limit even if it pushing 2000 W power into air...This is something like compare safety of a large 2 kW spotlight with a tiny 2 W laser. Yes, 2 kW spotlight produce a lot of light, but its safe to see on it from some distance. But if you try see directly a 2 W laser from the same distance, it will lead to eye damage and blindness... Despite the fact that it's very tiny and has just 2 W power.This is because laser has very high power flux density, so it give very high concentration of energy within a limited space volume. The same happens with a very small antenna, it has very high concentration of energy within a limited space volume around antenna... But the problem here is that people don't see these fields, so they don't realize that a large antenna is much more safe than a tiny one...

author: wizard69
author_rank: Super Contributor
timestamp: June 23, 2023, 09:34:51 pm
content: Quote from: nethawk on June 17, 2023, 12:14:38 amI don't by it that it is real. However I'm opened minded enough to ask for credible evidence from sound scientific testing. I doubt you can find such though. Besides that Electrical magnetic fields will come from any device, microprocessor or not. You can't have the magnetic without the electric. Any magnetic fields generated by a microprocessor would be so minute compared to the rest of the hardware to be impossible to notice.