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What happens when you touch a pickle to an AM radio tower

jeffgeerling.com

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Re: What happens when you touch a pickle to an AM radio tower

#121

Post by quickthrowman »

SoftTalker wrote: post #72
justanother wrote: post #40

I understand he got permission and everything was checked out by actual RF eggheads, but damn. I won't even change a HV run capacitor unless i'm wearing crocs, standing on cement, and wearing the rubber oven mitts. And even then, I keep one hand behind my back. Because there have been accidents, and they hurt (the pool pump run cap fails approximately annually in this climate and if I paid someone to change it every…

Just short the terminals with a screwdriver before you touch anything else? (Look away in case there's an brief arc flash)

Ideally you’d short a run cap with a suitable resistor, but you’re right, short the cap right after de-energizing the motor circuit before touching it with your hands.

Re: What happens when you touch a pickle to an AM radio tower

#122

Post by pclmulqdq »

timr wrote: post #111
hermitcrab wrote: post #110

Earlier quoted context omitted.

I had no idea that radio towers used that sort of ampage.

I might be misremembering the tower (i.e. I might be remembering the amperage for a 50kW tower), but they definitely do. Amperage on a 6kW tower will still be more than enough to kill you.

50 kW is a respectable AM station, while 6 kW is pretty short range.

Re: What happens when you touch a pickle to an AM radio tower

#123

Post by mlyle »

CobrastanJorji wrote: post #86
JCM9 wrote: post #62

For folks wondering why these sort of videos (there are lots on YouTube) always focus on AM towers: 1. On AM the radio energy literally pulses (the amplitude modulation) and thus the arcs of plasma will pulse too thus creating the audio noise. AM has a carrier wave that’s constant but the two sidebands of signal pulse from zero energy at silence to more power the louder the sound being transmitted. FM signals broadca…

Why would we want aviation radios to operate in AM? Is it just that we standardized on AM before the 60s, it works well enough, and migrating would require a worldwide effort? Or is there some interesting advantage to AM for planes? Maybe superior range?

To answer you in a different way:

Today we would build these systems with FM or digital voice.

But there are enough advantages we've gotten used to (graceful degradation, better handling of doubling, etc...) that it's not really unequivocally a win to switch to FM. There would be downsides that anger existing users, and it would be expensive, and the net benefit would be relatively small.

Re: What happens when you touch a pickle to an AM radio tower

#124

Post by upofadown »

CobrastanJorji wrote: post #86
JCM9 wrote: post #62

For folks wondering why these sort of videos (there are lots on YouTube) always focus on AM towers: 1. On AM the radio energy literally pulses (the amplitude modulation) and thus the arcs of plasma will pulse too thus creating the audio noise. AM has a carrier wave that’s constant but the two sidebands of signal pulse from zero energy at silence to more power the louder the sound being transmitted. FM signals broadca…

Why would we want aviation radios to operate in AM? Is it just that we standardized on AM before the 60s, it works well enough, and migrating would require a worldwide effort? Or is there some interesting advantage to AM for planes? Maybe superior range?

>Is it just that we standardized on AM before the 60s

This one mostly. As otherwise mentioned, there is some advantage in the case of multiple transmissions at once for AM, but in practice both are often entirely garbled. The loud tone caused by any slight difference in transmit frequencies is the big indicator that something has gone wrong. If one signal is much stronger than the other then that tone will be very faint and will likely be missed. So AM has something like FM capture effect in that case.

AM has allowed for very narrow channels on the aviation band. In Europe mostly, the channels are only 8.33 kHz apart. Typical narrow band FM voice communication requires 12.5 kHz.

Since the end points in aviation are usually within line of sight of one another, radio communication is very easy. Any modulation method would work well. Of course in practice this means that the equipment is allowed to degrade that much more before anyone gets around to fixing it...

Re: What happens when you touch a pickle to an AM radio tower

#126

Post by tpoindex »

linuxguy2 wrote: post #90
geerlingguy wrote: post #46

Earlier quoted context omitted.

It's also in bordered by two farms, with a flood plain across the street, in a rural part of St. Charles County, in MO. Granted, home builders keep building subdivisions closer and closer, but just 10-15 years ago the closest residence was a mile or so away (outside the couple farm houses). There's also danger/warning signage around the entire property, on all fences (including those around the towers).

Is that the KH0J transmitter? I've driven past that countless times and it seems so run-down I've often wondered if it was still transmitting. So many times I've wanted to park in the lot and take a gander... Probably for the better that I haven't!

Seeing the frequency on the sign with the FCC station ID brought back fond memories of the former licensee, KIRL. I listened to 1460 in the late 60's and early 70's when it played top 40 rock and roll. A nice alternative to the top 40 powerhouse at the time, KXOK 630.

Re: What happens when you touch a pickle to an AM radio tower

#127

Post by jdironman »

SoftTalker wrote: post #109
jdironman wrote: post #101

Earlier quoted context omitted.

Well, your comment was my deep laugh for the day. excellent story. When I was younger, I saw my father working on a ceiling fan...while it was on. I asked him why he did not flip the breaker first and he said "well, as long as you don't touch both wires at the same time, you'll be fine " Fast forward a few days later I am at school, and I see in one of the outlets one of the prongs for a power cable had broken off in…

In theory, if you were wearing rubber shoes and not touching any other path to ground, you would have been fine.

I think supporting myself by holding the metal of one of those school desks was a factor possibly.

Re: What happens when you touch a pickle to an AM radio tower

#130

Post by chadcmulligan »

geerlingguy wrote: post #59
chadcmulligan wrote: post #43

you can light up fluorescent tubes as well https://youtu.be/SDL9O2Fwb64

We actually tried that experiment; the tubes we had were a little older, so not sure how much that affected it vs the power at this site (the middle tower is 7 kW, which is a lot less than the 50 kW towers at more mid/high power AM sites). But it didn't light up near the tower. It did near the RF circuits above the phasor, though!

I have heard the story a number of times from old radio guys that it works
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