[telecom] Re: Cord PBX shown in new TV show

Wow...He needs a hobby...like, ummm...ham radio?

***** Moderator's Note *****

He already has one: busting my chops. ;-)

Bill Horne Temporary Moderator

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You mis-understood what Bill said.

That's -not- sequential numbering, but parallelism.

He already has his hands (and then some) full, without any other distractions.

He's just living up to the family name, after all -- when the 2nd vowel isn't silent, but given a 'long' intonation.

***** Moderator's Note *****

Harumph.

I concede that times and morals have changed, but I'm still uncomfortable with the boy having what seems like a harem at his beck and call. I suppose every father thinks his kid is wasting his life and not preparing for the future and is headed for a big fall, and I'm no different, but I still see him spending time with a group of young men I consider to be losers, and I'm not sure if it's a normal phase or if he's really begging for trouble.

I suppose I'm also like most fathers in that I constantly recite a littany of advice about how quickly the years will pass and how important it is to look ahead and work hard and not waste time. It's really the voice of my guilty conscience reminding me of my wasted youth, but c'est la vie: I figure if 1/10th of it sinks in, I'll have succeeded.

There's an old poem that comes to mind (I don't know the author):

Adam was the only man who never drove his offspring wild with stories of how much rougher things were for him when he was a child

He just passed his Board of Review and was awarded Eagle Scout rank: I guess I did most of it right, but it's still a father's job to worry.

Bill Horne Temporary Moderator

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Three RFI stories come to mind. In my case every time I'd key down on 2m I'd obliterate cable channel 18. I was running minimal power when it happened too. Turns out that Cox at the time wasn't properly grounding their drops. Ooops.

Then of course drive through a parking lot and key up on 2m and you'd set off every TRW built alarm system.

But the best is one that happened to a friend. He played on HF quite a bit but being the city, he was < 20 feet from the neighbor. It used to absolutely trash the neighbors TV, phones, etc.

Finally one day I negotiated the peace between them.

I Explained how to trap the TV RFI but found out why the neighbor was so upset. He was a sales rep for Keebler and he had to transmit his orders via a Telxon unit connected to the phone. When my buddy was operating it would kill the transmission. I also got my buddy to agree to an RF quiet time between 6PM and 7PM. That seemed to keep the peace until my buddy moved out for greener pastures.

***** Moderator's Note *****

My first rig was on six meters, and I was, to put it mildly, popular with the neighbors ;-). Of course, this was in the sixties, before cable TV, when most people still used rabbit ears and TV front-ends were as broad as a barn door, but of course a fifteen-year-old kid can't say that to an adult who paid a week's salary to hear WA1FXU calling "CQ".

Bill Horne Temporary Moderator

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Years ago I would come in on people's TVs and the sort, I would give out RF filters to take care of the problems until one day a neighbor came to me and said that his TV service guy told him it was my filter that blew his TV out. It seems the service guy had messed up the set and wanted to pass the blame unto someone else, this finally went to Small Claims court and I won out. That was the last time I ever gave out filters, I told the people to go down to the nearest electronics store; Radio Shack was just getting started at that time. One funny side note was that I used to come into a neighbors electric organ, that was strange and never could find out why.

In article , > > ***** Moderator's Note *****

And that's the other thing. Nobody understands that Part 15 devices pretty much have to accept interference from other licensed services.

It was interesting explaining that to my friends neighbor. I still see him on occasion. He still works for Keebler.

***** Moderator's Note *****

The onset of two-meter repeaters and FM instead of AM in the 1970's probably removed most TVI: NTSC video is transmitted using AM, and ham transmitters that used AM, even at low power, could mess them up very easily. FM, OTOH, didn't seem to cause any issues: cable TV was just catching on in the 70's, so that might have been what cured the problem.

I did have an issue with an early wireless telephone. The handset, which transmitted on 49 MHz, was prone to interference from a "birdie" signal: there was a local FM station around 97 MHz which would come in along with my FM signal, and I grew so tired of explaining to the guy what unintentional mixing was that I broke my own rule and put a length of coax on the input of his "base" station, cut to reject

146.22: it worked like a champ.

Bill Horne Temporary Moderator

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Oh, I understand that. But why? This is something that's always been something of a mystery to me. "This device must accept any interference received, including interference that may cause undesired operation."

What is the purpose of this requirement, and do I as a design engineer contravene FCC regs when I design a circuit with good EMI rejection?

"Accept" means "tolerate" in the legal sense. What it means is that the FCC will not intervene if your device suffers interference from another legal device. Part 15 does not give you exclusive use of a channel.

Even Part 97 isn't exclusive use on all bands. Sure we have the 2m allocation pretty much to ourselves but 70cm is shared with things like wind profiler (doppler) RADAR sites. Nearest wind profiler to me is in Chatham, MA.

And, in some cases the hams have secondary use of the band and have to accept interference, while in other cases the hams are the primary users and other users have to accept interference from them.

47 CFR section 2.106 will tell you for sure about any given frequency if you have a question.

--scott