Interesting RF issue

[blindfire]

Ok, well, not really an issue, but it is interesting.

Right now, my shack is temporary with my HF setup. The coax is running from the back of my radio in the basement. It runs a couple feet from me, across the basement and then under the door out to my antenna up on my deck one floor up.

I know I'm getting some RF exposure with this setup, but I don't xmit all that much.

Today I was throwing out CQ DX on 20M. I have my ICOM IC7100 setup with a wav file that calls out my CQ and repeats it every few seconds.

Well, I had my iPhone 6 Plus sitting next to the coax. I happned to look over at it and noticed that the Card Pay feature pops up from time to time when I transmit.

Makes sense I suppose since Apply Pay is RFIDS based (I think)

What is your strangest RF interference on HF?

 

[knoxy]

Back in my twenties (mid 90s) I had a couple hippy roommates. I came back from work one evening an they were freaking out about voices coming from the speakers. Given that they were typically high as ****, I humored them and checked the speaker. It was completely unplugged. I called them retards and took their beer.

Few minutes later, a some static started coming from the speakers and then a raspy woman's voice uttered something unintelligible. Definitely freaky.

Figured out it was CB traffic. Turns out the next door neighbor had a large antenna on their radio that was pumping enough power to drive the speakers from across the street. I was an EE major at the time, so I didn't freak out but it was pretty weird.

 

[drgrant]

Jesus now you did it, I could write a 3 post long screed about my misspent youth involving misuing RFI for nefarious purposes. I'm going to have to sidemark this for later when I have more time.....

 

[blindfire]

Jesus now you did it, I could write a 3 post long screed about my misspent youth involving misuing RFI for nefarious purposes. I'm going to have to sidemark this for later when I have more time.....

Curiosity level = piqued.

 

[cockpitbob]

Curiosity level = piqued.

Yup.

 

[drgrant]

Curiosity level = piqued.

I may have told you this one, but I'll post it here anyways....

Many years ago (Circa 1999?) me and an extra class ham friend of mine used to make trips up to HRO in Salem. It was almost a monthly pilgrimage, or we did it 6 times a year at least.

Part of this ritual was that we would buy iced coffees at the dunkin donuts on rt 28 on the way up because back then there was no dunks on the southbound side, so we'd get our coffees beforehand.

My friend and I quickly discovered that the muzak system inside the Salem DD was highly susceptible to RF, it decoupled rather easily into the speaker system in there. Like you could dominate it with probably under 100 watts.

At the time I had an Icom 706mkII backed by a 700W amp, mostly running on 11M but my friend would run it on 10M while we were mobile and would actually do morse with it while we were driving.

Needless to say if you put that rig on AM, keyed it and started talking, it had some punt. I always kept the drive pretty low on AM to keep the output clean, but it still had serious sack.

So one day I parked outside the dunks and gave my friend the mic, I left the car running. I think I set it up on 27.185 (ch 19 cb). I went in to get the coffee.

I'm standing in line in the DD, there are a bunch of teenage girls behind the counter running around making the coffees. As I'm standing there, all of a sudden the muzak just STOPS and then I hear, at maximum volume (there was no way you wouldn't have heard it, unless you were deaf, that's how loud it was....)

"MAKE THOSE DONUTS, WITH EXTRA GREASE!! THIS ONE'S FOR, THE SALEM POLICE!!!!"

The few patrons in the place start laughing their ass off, and I have to bite my tongue to avoid giving it all away, I walk up to the counter and I'm like "wow someone taken over your speakers" the girl is like "yeah we hear that all the time but not usually like that." I pay and leave.

Then I get back in the car, put the coffee in the cupholders, etc. Then I can see one of the girls through the window of the store. I taste the coffee. It's pretty good. I keyed up the mic and said "Thanks for the coffee, its really good!" then simultaneously like 2 girls like whip around and point right at me through the window, I smiled and waved... they were absolutely dumbfounded.

This was not the first incident, either. Another time I sent my friend in there to get the coffees. I keyed up the mic and belted out my rendition of the meow mix song (I want chicken, I want liver, etc.).

He said there was some old guy, who looked kinda like a bum in there, who got up out of the little booth he was sitting at, and he waddled forward a bit on the floor and then looked up at the speaker and pointed, and he was cursing at the speaker, pointing at it and he yelled "DEY DONT SERVE NO CAT FOOD IN HEEEEAH!"
Then apparently 2 seconds later I keyed up the mic and went "MEOW!" My friend said the bum recoiled in horror at the noises from the speaker, and then he was intimidated and sat back down in his booth.

As it turned out that location was VERY susceptible to RF, because the way I figured out the entire exploit was by virtue of the fact that I heard a truck driver on rt 28 come over the muzak system one day,,, but its usually pretty brief.

Ever since the store got remodeled/rebuilt I don't think it's exploitable anymore, probably much better installed system.

Other ones I can think of off the top of my head...

Friend of mine who was a bartender at one of the VFWs in central MA... he'd go on break and talk on the radio in his car, talking to us using SSB. He had an HR2510 and probably a 2 transistor amp with it, maybe 150 watts or so, tops. He said one night he was sitting in his car, without the motor running, and he keyed his radio up and HIS CAR STARTED. apparently the remote starter in his car was susceptible to RF. Ever since that happened to Tom I lost any interest I ever had in getting a remote start unit for my car...

Another favorite pastime was drive in restaurants, like Carols in Fitchburg, or Conrads over in Lunenburg. Whenever an announcement was made over the speaker for a ticket number, you could key up and either drown it out, or talk back to them. I think it was at Carols once, they called my number, I keyed up and said "Thank you so much, I'm pretty hungry. " When I came up to the window the girl looked at me like I had two heads.

There's more, but I gotta get back to work... for now.



-Mike