开云体育

On Friday 14 February 2025 09:40:38 am wn4isx via groups.io wrote:

Is there a local ham you can talk to via telephone while he monitors your audio?

As to coupling a PC to a transceiver, yes it can be done, transformers are good for breaking ground loops but bad for picking up stray magnetic shields.

These show several ways to do it.

The first thing I thought of when I saw "mic input" was the possibility of overdriving it, but both of those links address this issue.

Mr. Browne knows hit stuff, both RF and AF. He was a respected audio expert for ~40 years before retirement.
I use transformers but they are obscenely expensive units with integral faraday cage, electrostatic shield between primary and secondary.

Jensen makes similar transformers (prepare to rob a bank). I salvaged the transformers from an audio distribution amp designed back when we (professionals) used 600 ohms for everything audio, then we went with 10K loads and the old distribution systems were tossed.

I'm not sure I see the need for something that fancy...

Rod Elliot shows two circuits that can modified to drive a transceiver,
one for transmitting one for receiving



The PC to PA can be modified for PC AF out? to transceiver AF in
The PA to PC can be modified for transceiver AF out to PC AF line in.

If you are lucky, in a location or ham shack with no stray electromagnetic fields, Mr. Elliot's designs should work fine.

Funny that he mentions phone transformers. Some time back I scrapped out a bunch of modems, some PCI bus but most way older than that, most "winmodems", unusable for me as I don't run windoze. There was a transformer on each of these, and assorted other useful bits. It's interesting that he shows different dc resistance for primary and secondary, I'd have thought that they'd both be the same.

Some years ago a friend of mine (who was a sound engineer) pointed some small transformers out to me in the Mouser catalog. They were fairly cheap as I recall. He said that they worked quite well if you had a resistor across each winding, otherwise they tended to ring with higher signal levels.

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Wednesday 12 February 2025 03:02:39 pm wn4isx via groups.io wrote:

Cat 5 cable is specified as having 100 ohms +/- 15% [really tight tolerance there.]

Interesting as each pair has a different rate of twist...

Single pair twisted, solid, PVC insulation with about 4 turns per foot has about 120 ohms impedance at 3.5MHz, but, at 7MHz it drops to 100 ohms.

I intend to try using some of that stuff for audio, and seeing how it performs. No idea of the rate of twist.

When I was 12 I'd purchased some military surplus field phones and figured out how to wire them into the public switched telephone network. This would have been the spring of 1963. The phone company detected my illegal phone and sent a repairman out to resolve the issue.

A friend's apartnemt in NYC was rather sprawling, and they had two phone lines coming in. Since there were no connectors involved, just the little 4-screw terminal blocks, they got the longest cords that they could get. I have always wired in extension phones when we wanted them, and in one place even ran wiring inside the walls, though that crawl space above the apartment was a real bear, with loose insulation all over the place. I knew about disconnecting the ringer, and found that a neon indicator would work well and they never detected those. At one point I'd acquired a box with a row of buttons for a multiline setup and the wall phone that it was supposed to work with, and managed to figure out how to get that working. I could actually put somebody on hold. :-)

This was when you had to rent everything from the phone company, for Lexington that was GET.
Mr. Otterback was nice about it he, he explained the phone company had what was called a monopoly and would move heaven and hell to protect it and woe be to little boys who break their rules, and the law.

Yeah, up until the AT&T v. Carterfone decision, I forget when that was.

He took my phone

That ain't right. I used to have fun with phones just connecting a pair of them and putting a bit of DC on the wires. It didn't take much to allow you to talk to each other. I tried this with going across the street, but didn't have quite enough wire and the splice in the middle didn't hold up to the tension.

but left me a unused 300 foot "spool" of inside wiring, the single twisted pair described above.

Jacketed? The stuff I referred to isn't. I also at one point had a couple of boxes of what they called "station D" wire, which was four wires in a jacket. One box was off-white, the other one was gray. That's the stuff they used to use for inside wiring before they went to twisted pairs. It was _not_ twisted. I guess that became a thing when they started providing phones with lights in them, like the princess and trimline.

The man across the street was also a phone guy, he'd heard of my misadventure and dropped off a Barbie Pink "princess style" phone.

I guess those were a thing because of styling or something (the other pair was for the light in the dial, it was wired somewhere to a small plug-in transformer). I always found them awkward to dial.

He'd removed the ringer and explained how the phone company had a computer that checked each line at least once a week, ringers had capacitors that were inline any time the phone was on hook, and their computer could detect the extra capacitance.
Now we lived 5 miles from the central office and I've always had some doubts about that version of reality, I have no specific reason to doubt our neighbor told me what he believed was the truth, but I find it difficult to believe the phone company could detect a few extra uF 5 miles away through multiple cable splices etc.

I'd heard the same thing, dunno how they figure it but yeah, it was the ringer that they'd detect.

Now the phone company never came back, so maybe he knew what he was talking about.
I still have the phone, I've used it as a butt phone (the phone they use to check lines.). New ones have DTMF (touch tone) and the newest support VOIP (voice over IP)

I hadn't heard about that VOIP capability. I do have a butt set, and it's come in handy. I traded for it on a service call where this gal who was doing some other work there at the site really didn't know what she was doing. It was a fairly large retail store and somebody had used a hunk of 25-pair (!) to connect two boxes, and the lines involved that went through that just weren't working right. I ended up ripping that out and puting a couple of lengths of cat5 in there, fixed it right up.

We haven't had a landline in over 30 years, I haven't used my "butt phone" in ~20 years,

I haven't used mine in ages, either. Or the toner, or the punch-down tool...

Cell service out here used to be pretty spotty. You'd have to go to certain specific spots on the property to be able to make or receive a call. It's gotten a lot better in recent years, new towers in the valley and such, and I even get a "5G" indication on my phone. She still likes to have the land line so we're not getting rid of it just yet.

Though the phone company is as usual screwing things up. For a good long while we had DSL for internet, and the last time the modem died the unit they expected us to use insisted on being 198.162.0.1, which IP address is already taken here by a file server, and you couldn't configure this thing to use anything else. I went back and forth for a good long time with "tech support" who kept on telling me stuff that wasn't right, and finally when the guy started going on about how many years of experience he had with this stuff I told him that I'd been a technician since probably before he was even born, and that he didn't know what the hell he was talking about, and we told 'em to remove the service from the line. Then got a dish out in the yard within less than a week. The latency is a bit annoying, but it's tolerable.

I have no idea if the local phone company still accepts rotary dial "signals."

That friend of mine I mentioneed above stuck with rotary dialing for the longest time. He would have liked to get touch tone but he didn't care to pay extra for something that cost them less to provide. When they upgraded exchanges from the older electromechanical setup to electronic switching (required if you want to use touch-tone) they had to put a bit of stuff on each line to continue to use pulse dialing. So it cost them more, but for some reason the phone company would charge you more money to use touch-tone at that time.

I still have probably at least 200 feet of that cable, I've used it for several dozen 'Wire wrap" projects.
I used quotes because I soldered.

No idea without looking how much cat5 I have. At least that stuff is foot marked, and no idea at all about those two spools of non-jacketed stuff. Also a partial box of RG6, which I used to do video cabling in the place next door. Probably hundreds of feet of each. I am NOT fond of F connectors, not at all, though I have a pile of those and the special tools to strip and install them.

I remember a guy who had s business where that's all he did, phone wiring for people. This was after the phone company gave up on claiming to own everything and wanting to rent you stuff, and people had to be responsible for their own inside wiring. But that was years ago, and I doubt that he's still around and in business.

All that specialized stuff, not going to use here. It's a shame, really...

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Tuesday 11 February 2025 05:02:08 pm wn4isx via groups.io wrote:

I found about 200 feet of our coax missing and replaced with zip? cord.

Wow, that's really odd. And whoever did that didn't think that it'd make a difference?

Zip cord has something like 100~130 ohm impedance, depends on the number of strands, insulation plastic,? color, spacing, phase of the moon. 75 ohms to call it 115 ohms might not be horrible for a transmitter with a transmatch, but wow it sure trashed the video.

I have a bunch of cat5 cable, left over from when I used to do that kind of wiring (and all the stuff that goes with it), and also a couple of spools one of which has a single twisted pair, the other has two twisted pairs, used for making a connection in a phone system, 66 blocks or whatever. I'm wondering what the impedance of that stuff might be, or the pairs in cat5, each of which is twisted differently to deter crosstalk.


--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Tue, 11 Feb 2025, Roy J. Tellason, Sr. via groups.io wrote:

The one thing that sticks in my mind with regard to those companies, big or small, is how arrogant their attitude is. The junk mail was incessant, and I couldn't get them to stop. Asking one of their phone reps how to stop it got me the suggestion that I file a complaint with the Federal Trade Commission...

our government will always be on the side of who ever contributes the most to their campaign fund

On Tuesday 11 February 2025 08:58:49 am wn4isx via groups.io wrote:

This might be of interest to radio enthusiasts in this group.

Cable TV systems have always had problems with RF leaking from and into their "closed systems."

This is a bit one sided industry view that is nonetheless interesting.

Read all 3 parts and then the Distributed Access Architecture.



At one point the local cable system used a pilot tone smack dab in the middle of the 2M ham band to set the automatic gain of their 'gazillion' line amplifiers. Their system leaked like a sieve and a group of local hams sat up an impromptu network on that frequency, which shut the entire cable TV system down.

Heh. :-)

The cable system was violating the law with excessive leakage. The same technical flaws that result in leakage that allow radiation of cable TV signals also allows external RF to get in.

The cable system issued vague veiled legal threats, which resulted in the FCC paying them a visit with an order "Clean up your act, now."

Right...

No cable anywhere around here, and no prospects of cable anytime soon, it's too rural and spread out. Places where I used to live were another story. One place where I lived I had some coax running from one window to another. Looking out the window one day I see this cable truck sitting outside and a guy climbing a ladder, wire cutters in hand. I leaned out and came real close to dumping that ladder over, with him on it. He climbed back down and got on the radio in his truck, then telling me that his supervisor wanted to talk to me. I declined and told him to get off the property, since he was screwing with something he had no idea about. That company was a smaller local outfit, based in Hershey, later on gobbled up by whoever, eventually comcast, I think.

Last place I lived before moving here the building across from me, visible from most of my windows, had all sorts of cable hanging on the side of the building, which had a number of apartments in it. This was comcast, who apparently has some kind of a setup where if you're a subscriber and have internet you are also providing the wifi to any other subscriber, anywhere in the country. So every single one of those wifi devices was parked on the same channel, which happened to be the channel I was using also, though I'd set mine up before they came in there with their crap. Leakage out of that system was pretty bad, too, though I didn't find it interfering with ham radio activities much.

The one thing that sticks in my mind with regard to those companies, big or small, is how arrogant their attitude is. The junk mail was incessant, and I couldn't get them to stop. Asking one of their phone reps how to stop it got me the suggestion that I file a complaint with the Federal Trade Commission...

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin