For those of us licensed in other countries it comes as something of a surprise to find that American radio amateurs now have to run RF exposure calculations as part of their licence requirements. [Ham Radio Crash Course] as approached this in a unique fashion, by running around 800 watts of 6-metre power into a vertical antenna festooned with hotdogs. That’s right, this ham is trying to cook some ‘dawgs! Is his station producing dangerous levels of power that might cook passers-by?
Of course, aside from a barely-warmed line along where the ‘dogs were attached to the antenna there’s no heating to be found. But we think he’s trying to make the point in the video below the break about the relative pointlessness of applying RF field limits which are definitely relevant at much higher frequencies, to hams at low frequencies.
It leaves us curious as to how that 800 watts could be efficiently transferred into the sausages and really cook them. Strapping them to a vertical is we think the equivalent of strapping anything resistive to a conductor, they do not form a significant enough part of the circuit. We think that even six metres could cook a sausage if it could be efficiently coupled into it, so we’d suggest putting a grounded sausage up the middle of a close-wound helix.
If you have any thoughts on the RF exposure calculations, or on the best way to cook a ‘dog with 6m, we’d love to hear the, in the comments. Meanwhile, this isn’t the first piece of ‘dog-based shenanigans we’ve brought you.
Well, it’s not April 1st this time.
Field Day just got real!
In DE you have to make always a documentation with a calculation (or measuremet) for your stationary rig and send it to a federal bureau. To proove that your transmissions do not exeed defined radiation powers at your properties borders.
Reminds me of revoking that documentation because I removed the antennas on my roof for the PV installation.
Exactly, it is requirement of every radio operator in every part of world to respect local AND international law / band plan ….
AND in USA there is requirement for measuring / calculating radiated power for LAST 25 + years.
And i do not know country which legalises any harm to other people in general…
Hackaday is no longer what it used to be. This clickbait bull… is almost in every second article in here.
>Exactly, it is requirement of every radio operator in every part of world to respect local AND international law / band plan ….
Nah, lol.
“AND in USA there is requirement for measuring / calculating radiated power for LAST 25 + years”
Citation please because I just upgraded from tech to Extra and, no. No there is not.
47 CFR 97.13
That rule doesn’t say what you think it says and lists all the rare circumstances where 99% of hams don’t even have to think about it.
Yeah, and getting 800W licensed, isn’t as easy as ticking a box on some request-form… in fact, in AT you can’t get it as an individual…
Right, 400 is Max for Private. Im class B 200w but never came close. 100 works fine. 1000 is for Club stations. 73 de OE3MKW
DE allows 750 on most bands. But I would never use that much. Also because you could never comply with the EMV (don’t know what that is in English :-)) regulatory if you do not own a very big property.
Back in the day (~70s) 1400 weren’t unheard of, either.
The ol’ FL-2000 could do that with the right tubes. Err, I heard, mean.
Anyway, these were serious power levels (QRO).
Compare that to the modern day softies who make such a big tamtam (fuss) about 100W or think that 10W isn’t QRP anymore..
Back in the day, 100W barely qualified as QRO. It was just normal power output, like 25W was. It was used to drive tube PAs.
That being said, I agree that EMV calculations have their place. Modern day tech is badly shielded “sunshine technology”. Also, heart pacemakers are such a thing.
While in practice they aren’t affected much (the human body works as a shield), it’s better to not gamble here. Hams should never cause harm to their surroundings.
Quick explanation here: Back in the day, the power limit (Watt) was defined by the plate dissipation (“Anodenverlustleistung”) of a tube rather than the absolute output power.
We’ve been working with a German company for the last month for IT products, and it’s unbelievable the degree of bureaucracy that Germany has. Things that should take 15 minutes take 4 days.
It makes the US state department look about as complex as ordering food at a Waffle House, and has guaranteed I will never set foot in that country.
It’s not quite helical, but maybe a traditional spiral Cumberland sausage would provide better coupling?
Wonder what a hot-dog matching network would look like..
Now that’s food for thought…. Sorry, Just had to say it.
I just hope they call it Sausage Link
Issue is totally diferent – in era of 5000 miles 5 watt WSPR contacts having to use EIRP in upper part of allowed limit BY DEFAULT is demented.
American operators are notorious for jamming for example caribbean and north side of south america ( there are even interesting stories from ESA Space Launch Facility in French Guyana ).
Also funny enough, most of world has lower limits on EIRP then USA, because of ” US supremacy reasons ” XD
Heating by RF comes from the dielectric losses of the materials that make up the food. In other words, the electric field is the important bit. So if I wanted to cook a hotdog, I’d build a cavity resonator with a resonant mode (at the appropriate frequency) which produces a hotdog-shaped electric field, and excite that with my RF. Perhaps a cylindrical cavity with the hotdog at the centre, aligned axially.
I’ve got an easier way.
50 ohm terminator on the end of the cable. Drop the hotdog on top. Problem solved.
Or just use the hot dog as the dummy load (with appropriate impedance matching network, of course).
Or better yet, throw the hot dog in a microwave.
3 minutes and you’re ready to put it on a roll…
Now if you had tried 600w at 23cm, you might have acheived something, we have to do these calculations in the UK now as well, but using a ofcom supplied spreadsheet, but it’s very easy to comply
https://rsgb.org/main/technical/emc/emf-exposure/
We have to do that in the UK too. We are not surprised USA is doing the same.
The ‘trash can filter’ described in the QST magazine, June 1972 page 48 – which uses an actual metal garbage can as a RF filter – describes cooking a hot dog with 100 watts of two meter RF in 5 minutes and a hamburger in 3 with 200 watts. Here’s a link to the article – check it out it’s pretty cool: https://worldradiohistory.com/Archive-DX/QST/60s/QST-1972-06.pdf – The garbage can makes an excellent RF filter too!
I remember that. And good for the Baofengs
Baofengs are excellent radios for the purpose of stimulating the appetite.. for both hot dogs and more investment in the hobby. They lower the barrier to entry. People complain that amateur radio is dying. And it is. Getting your license feels like joining the Freemasons. It’s very weird, then you have to drop a boatload of money and f around up on your roof. Go figure.
“People complain that amateur radio is dying. And it is. ”
I’m okay with that. As long as it’s dying, it’s not dead yet. 🙂
There’s a saying that “those declared dead live longer”. 🧟♂️🧟♀️
But please use a new, clean garbage can… Of course you can leave the cooked hot dog inside, as it is mostly made of nasty stuff too, at least to some extent.
Those hot dogs are placed near the end of the vertical, which is where the voltage is maximum but current is a minimum, therefore heating of the antenna element is probably minimum. As for heating them with the field… that would be awfully difficult to predict without writing some custom simulation code, because I’m sure your garden variety NEC was written and calibrated to get the results of the far field correct, since that’s what you’re normally interested in.
I know the post is all fun and games, but RF radhaz doesn’t necessarily need to cook people to be a hazard…..
Seriously, the biggest potential is inadvertent exposure of RF to the operator from an ungrounded rig or one with a high impedance (inductive, etc.) ground with conducted RF into microphone and headphones, etc.
Stay safe !!
New contest… what’s the lowest band for which you can make a resonant hot dog? Can’t wait to see someone produce a sausage for the 600 or 2200M bands!