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BlackCoffee
| | Posted on Monday, November 24, 2003 - 8:52 pm: | 
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I was pulling into Fuddruckers tonight to get a burger and was running my rig with my 2 X 4 on. It is under powered (small alternator) as I get about 600-650W out of it (maybe on a good day at 80mph), BUT my wife was sitting in the parking lot in her Toyota van. I was about 500-600 feet away from her and she could hear me keying up. Her radio was on 91.9 FM (regular radio) with no problems hearing me at all. She was like, I could hear you for a good 10 minutes. Conditions were rainy and I was on Ch. 11 AM. Man, I think I better turn things down or somebody's respiratory might cut out or reset?
I have heard of someone keying and resetting an ATM machine before, but that kinda freaked me out.
Any similar stories? |
Topten
| | Posted on Monday, November 24, 2003 - 11:52 pm: |
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No doubt, gotta be careful with that rf power, you never know what kind of havoc it could cause on those machines that could be keeping someone alive. |
Ss8541
| | Posted on Tuesday, November 25, 2003 - 12:07 am: |
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i'm sure bruce will have atleast 10 similiar stories. they may already be in the moderators que, but not posted yet. |
Kiwikid
| | Posted on Tuesday, November 25, 2003 - 1:09 am: |
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Hi Team,The following is not a recommended safe practise.
I remember when I was in my 4x4 and went through as KFC drive thru when I keyed up the fast food computor which holds the orders was erased,the electrical driven serving hatch window tried to jump the rails and also as I pulled up along side a fuel bowser and as I was topping up the gas tank my co-pilot keyed down on the radio and the figures on the fuel bowser register changed.The only problem I did not see which way the fuel cost went,for the good or worse.Reflecting on the events it was not the safest thing to do either.
73
Kiwi Kid |
Bruce
| | Posted on Tuesday, November 25, 2003 - 5:26 am: |
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Morning SS8541
The problem with RF is the machines are so loaded with electronics it dosnt take much to mess things up. OK funny story a CBer in Pinellas Park was parked outside a church ( this made the paper ) And proceded to rip into someone on the air .....Yep the PA was working TOO GOOD well the church called the cops .... Now myself the numatic tubes in the bank my 10 meter radio lockes them i was on 29.6 and they got very upset .... no sence of humor. Back in 71 my moonbounce station could light up the kitchen light across the ally ..... the guy was always complaining about my radio ...... one night i could see him and as he turned out the light i hit the transmitt button the light stayed on and i watch him fliping the switch on/off waited untill he was getting mad then unkeyed as he was leaving i keyed up again MAN did he get mad !!
IM a BAD boy.
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Deadlyeyes
| | Posted on Tuesday, November 25, 2003 - 7:26 am: |
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I do believe that you have just experienced "Front End Overload".
Front end overload is when your receiver begins to pick up adjacent frequency signals caused by either simple transmission or just unintentional harmonics so strong that the receiver becomes "desentitized".
Hmmm an example. You are at a party and just standing around you can hear everyone talking and can ever focus in on a conversation if you stop and attempt to listen. BUT then someone raises his voice near you to a very loud level and suddenly you cannot hear anyone else BUT them. His loud voice has knocked out your ability to hear anyone else.
As a general rule Front End Overload is the result of poorly designed receivers. The designers either deliberately or simply forgot to put in adequate filters to filter out unwanted strong adjacent signals. You see the extra components make each unit more costly/less profit. So they simply just do not put the filtering in to make more profit. Televisions are notorious for this.
Of course there is always the possibility of "Harmonics" as well. IF, note captialized, you have access to a Spectrum Analyzer you might have that amp checked out on it. If any harmonics land on public service frequencies. If its dirty you might want to use it only with extreme discretion. Better yet dont use it at all if it does land on public service frequencies. |
Wildbill
| | Posted on Tuesday, November 25, 2003 - 8:01 am: |
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I remember when my daughter was three, she keyed up my 8 pill at the gas station, while I went inside to pay. I came back out and all of the gas pumps were flashing zero, had to leave quick. I came back later that evening the station was shut down, I guess they couldn't get back up.
Wildbill |
Bullet
| | Posted on Tuesday, November 25, 2003 - 10:23 am: |
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ive got 3.
the 1st was a church my wifes family goes to a penicostal church.
i was sitting in the parking lot listening to the cb durring service and keyed once to say hi to a buddy.
my wife noticed my short 2 second voiceover and told me i came over and got onto me to stop.as she whent back in the little devel poped up on my shoulder and said lets get um! lol
i thought it would be funny to play the intro to iron maidens "number of the beast" through thier intercom. "whew doggie did that ever get em a rolling and a rocken".
my wife was out thier saying you got to stop!
thier freaking out, inside everyones in a panic praying to god to rebuke the devels from the church. lol
i know that was bad but that pracher had said some unkind things to my wife once and i couldnt resist the timing.
2nd was at taco bell, not a funny story really but they were not happy with me cause once i got my order through i went back to my conversation
and they heard nothing but me, quite upset when i got to the window.
3rd i learned i came over the pa at work so at nite durring lunch id page my friends to places and of coarse no one would be thier when they got thier. lol all in good fun. |
ChillyDog
| | Posted on Tuesday, November 25, 2003 - 11:45 am: |
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BlackCoffee,
(Excellent handle, by the way ...)
In 1993 I was called in to investigate a problem with a MRI scanner that intermittently had severe image quality problems.
Several times a week, sometimes for an hour or more at a time, the scans would result in very ugly, undiagnostic pictures. This had been going on for well over a month, and the radiologist who owned the MRI unit was mad while the service team who had been trying to fix the problem was highly frustrated.
As you may know, MRIs work with giant magnets and powerful radio signals. Their receivers require a very quiet radio environment, and so are installed in RF shielded rooms.
Shielding is on the order of 90 to 100dB or more of attenuation. Usually when problems of this sort happen the shielded room has failed; in this case the room tested good.
I went over the history of the failures and noticed a strange pattern. The failures occured on Tuesday evenings, once in a while on Wednesday mornings, and Friday afternoons. Only those times and never any others.
So that Friday I made sure to be on the MRI site with a general coverage receiver tuned to the MRI frequency. Right when the image quality of the scanner degraded I heard this terribly nasty, distorted, raspy, godawful AM voice transmission saying something along the lines of "Hey Strawberry, Tripple L is back in town, looking for a date!"
The signal seemed to be everywhere on the frequency bands. I was tuned to 62.86MHz when I first heard it, it was distinctly present at around 81.55MHz and was particularly powerful at 54.37MHz, but I knew right off the bat where it originated. Yup, 27.185MHz. A trucker at the truckstop about 1/8 mile away, looking for a lot lizard.
So I drove over and used my own CB to find him. Fortunately he was a nice guy, pretty ignorant of radio theory and operation but willing to listen and to learn.
He was running this garage-brewed 8 pill amp, driven by a cheap commercial 4 pill amp, which was driven by a 2 pill amp his brother-in-law made from a kit. The radio was a Cobra 29, no limiting, tweaked and peaked beyond recognition, with a cheap power mike turned all the way up. He told me he "really wanted to get out!"
He drove a regular route, stopping in the area Tuesday nights, staying over and leaving Wednesday morning, and dropping by for fuel on Friday afternoons! While he was at the truckstop, he'd chat on the radio for an hour or so.
His setup was so nasty that the transmitted harmonics and splatter were intensive enough to overcome 100dB of RF shielding a tenth of a mile away, and interfer with medical diagnostic imaging!
I bought Tripple L a cup of coffee and a piece of pie and we talked about radio for a while, with me drawing on paper napkins to illustrate the concepts of harmonics, splatter, and driving/overdriving amps. I convinced him to go to the truckstop CB shop. Turned out the tech there was a good guy who knew what he was doing, and after the tech used an o'scope to demonstrate what I was talking about the tech convinced the driver his setup needed "optimizing."
Optimizing consisted of repairing the radio limiter and correctly tuning the radio, removing the 2 pill and the 8 pill and setting the radio drive to run the 4 pill (the driver would not go without some "kick!"), and modifying the power mike to output a more reasonable audio level. I guess the driver paid with the money he meant to give to Strawberry.
Net result; Tripple L ended up with a much cleaner and better sounding rig, the MRI scanner stopped having image quality problems, and for the next couple of years, while he ran that route, Tripple L would give me a shout once in a while, usually on Tuesday nights. Over time he actually became pretty good at understanding radio, and when I last talked with him he was considering becoming a ham.
Regards to all,
Bob |
Ss8541
| | Posted on Tuesday, November 25, 2003 - 9:38 pm: |
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chilly,
who cares about the MRI?, we want to here more about that sweet innocent miss 'strawberry'. its a shame that because of you she didn't get her pay that day. |
BlackCoffee
| | Posted on Tuesday, November 25, 2003 - 10:25 pm: |
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ChillyDog-
Great story! Didn't realize that MRI's were so sensitive. Pretty cool how you tracked the frequency down too!
Thanks for the story,... definitely a good one!,... great ending too! |
Crafter
| | Posted on Wednesday, November 26, 2003 - 1:20 am: |
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When your mobile with a 8 pill dont drive within 50 feet of a radar site either! I just had to move. Had fcc,fbi,cia all in the same day! Good thing I wasnt active duty anymore. Knocked out the scopes and all at the army post airport. Who would have thought that thing would be so close to the street anyway. |
Saddletramp025
| | Posted on Wednesday, November 26, 2003 - 9:24 am: |
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If you want to see some real Front End Overload, Drive by the doors at your friendly local WalMart,put your radio somewhere around channel 28, turn your box on, whistle loudly, and sit back and watch the Front End Workers..(ie: Doorgreeters) go nuts trying to figure out why all the doors open at the same time. Just remember it also works in reverse, If the doors are open it will also close them very quickly, So don't knock any old folks down. |
Ryan
| | Posted on Wednesday, November 26, 2003 - 1:20 pm: |
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dont knock any old folks down? are you kidding? its old people pinball time!!! |
Bigbob
| | Posted on Thursday, November 27, 2003 - 8:08 am: |
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A trucker freind of mine had to sell his eight pill,his wife keyed up when he was outside the cab,he folded like an accordion,thank god for 911,he's allright now but his pacemaker was fried ,now he has to work overtime to pay his 120,000$ hospital bill,that eight pill only cleared away 2000 of it,live and learn.Bigbob |
Taz
| | Posted on Friday, November 28, 2003 - 2:26 am: |
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Car alarms, garage doors, house alarms, atm machines, gas pumps, radio controlled cars, model aircraft and the list goes on.
Definetley fun to mess around with..
Taz |
Hornet168ky
| | Posted on Friday, November 28, 2003 - 11:34 am: |
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Well here is my story. I was chasing some skip about a year ago. I was near New Orleans,LA. I was heading to a tank wash to have my tank washed out after delivering a load near there, and was on a back road,street, and I was engaged in a coversation with a friend of mine in Pittsburg,PA. When I happen to notice a police man following me then it happened he pulled me over. He was very nice about it tho. He explained he had been listening to my whole conversation......... on his scanner, police radio, and whatever else kind of communications device he had in his car. He kindly explained to me to cut it back a bit, especially down there.
I never really thought about it till it happened to me. I had heard others talk about no key down zones and did not know what it ment...........well I do now have a friendly copy of a nice warning ticket to remind me every day. So now I take notice of no key down zones.
Hornet 168 Ky
CEF# 219 |
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