RCA interconnects; why coax construction and not simple 2 wire?

[flightops]

WoW! That was intense. So dangerous...

walk in the park (well, more like a jog).



I've flown into a tropical storm 100 nautical miles off sable island to pull people off a dinky little sailboat in sea state seven. That at least got the pulse up....we were "pushing the envelope" a little bit on that one. We either made it back to Sable for fuel or to a local oil rig or we weren't making it back at all. Gotta "hang it all out" sometimes to get it done.

I like to tell guys I have literally fought the storm...and won.

lol!

That Others May Live

 

[Doodski]

walk in the park (well, more like a jog).



I've flown into a tropical storm to pull people off a dinky little sailboat in sea state seven. That at least got the pulse up....

Major danger! Thanks again. We are very fortunate to have people like you doing this stuff. People, saved by such rescues must feel very indebted and lucky. Did you do most of this in the Cormorant or the older Sea King as I think it's called or both? Is there another aircraft other than those two?

 

[flightops]

Major danger! Thanks again. We are very fortunate to have people like you doing this stuff. People, saved by such rescues must feel very indebted and lucky. Did you do most of this in the Cormorant or the older Sea King as I think it's called or both? Is there another aircraft other than those two?

Sea King is a sub hunter and flew off the Frigates. Replaced by the Cylcone.

My first ride was the CH113 Labrador:

That's 301 in the National air museum in Ottawa. Me and that old girl have gone out to sea many times. Before 301 went to the museum (the only one preserved in flying condition), I pulled down the insulation blanket by the manual hoist controls and signed one of her ribs. I also wrote that I thanked her for bringing me home all those times and then watched her fly off over the horizon....

 

[guy48065]

Data wiring twisted pair works on balanced transmission, just as it does for analogue audio. It works because the transmitter and receiver are both balanced and differential, so only respond to the difference in voltage between the two wires. External interference induces equally in the two wires, so cancels in the receiver. Balanced audio will work fine over unscreened twisted pairs for line levels, and not over long distances whereas low level microphone signals still need screening even with twisted pairs.

Incidentally, balanced twisted pairs also radiate out much less, so crosstalk between circuits is very much reduced.

S

I've got a box of interconnects I've accumulated over 40+ years of tinkering with hifi. I'll generalize and say I've had the best luck with 2C+shield configuration. That's a twisted pair with an overall shield. I haven't heard much difference in whether that shield is grounded at one end (float shield) or both ends. My experience is it doesn't matter much in 1M lengths.

In my previous home my system had the amps between the speakers, with 30 feet IC from the preamp to the amps. I tried several cables in that setup trying to eliminate hum & RF. The cable that solved the noise AND sounded great was a 4-conductor twisted with overall braided shield, grounded at only the preamp end, all Teflon sheathing. Randall Research "Symmetrical TX".
The 2 hot + 2 ground made the cable pretty fat & stiff. Maybe the larger-than-normal gauge helped with the long length... All I know is it was expensive but WORTH IT.

 

[Doodski]

Sea King is a sub hunter and flew off the Frigates. Replaced by the Cylcone.

My first ride was the CH113 Labrador:

View attachment 422473

That's 301 in the National air museum in Ottawa. Me and that old girl have gone out to sea many times. Before 301 went to the museum (the only one preserved in flying condition), I pulled down the insulation blanket by the manual hoist controls and signed one of her ribs. I also wrote that I thanked her for bringing me home all those times and then watched her fly off over the horizon....

Ahhh... One of those bad boys. Those are amazing. I've seen them flying and it's always a treat and special. Boggles my mind how one flies with two sets of rotating wings. So all in all do you prefer 301 or the newer Cormorant. I've read a little about the Cormorant and it seems a special aircraft with all it's capabilities.

 

[Doodski]

Maybe the larger-than-normal gauge helped with the long length.

Low level audio signal does not require much as per wire gauge but a little thicker wire in a longer run is a welcomed sight for sure.

I've had the best luck with 2C+shield configuration. That's a twisted pair with an overall shield. I haven't heard much difference in whether that shield is grounded at one end (float shield) or both ends. My experience is it doesn't matter much in 1M lengths.

Dependent on the class of grounding the connection at both ends or at one end may make a difference. It seems you where good to go with the method you chose.

 

[flightops]

Ahhh... One of those bad boys. Those are amazing. I've seen them flying and it's always a treat and special. Boggles my mind how one flies with two sets of rotating wings. So all in all do you prefer 301 or the newer Cormorant. I've read a little about the Cormorant and it seems a special aircraft with all it's capabilities.

Each has it's qualities. The Lab was a scalpel in hoisting operations, The Cormorant is a broadsword. The Cormorant has longer legs, which is important in this country.

The Lab was steam driven, the Cormorant was like stepping on to the bridge of the star-ship enterprise. Pilots had to actually fly the Lab everywhere, so their hands and feet skills were superlative. Cormorant has multiple automatic flight systems, so those skills deteriorated a bit in the corps.

Which is better? Cormorant is better for getting there, Lab is better when you are actually there. So meh, take you pic.

Lab 305 blew up in mid air from an engine fire/fuel dump and killed 6 of my brothers returning from a mission, Cormorant 914 hit the water on a ship hoist and killed 3 of my brothers.

914 messed me up for a while. I was supposed to be on that crew and a last minute schedule change put someone else on it. A good freind who came up with me from basic and another who I had trained and given him his wings. Third was a colleague and dear friend. Brothers all. Lots of survivor guilt to this day. Guilt doesn't make any sense because it wasn't my fault why it hit the water nor why I wasn't on it, but the mind/emotions can be a wacky thing sometimes.....

 

[DonH56]

Simple handwaving non-rigorous explanation:

If a signal (e.g. noise) crosses a parallel pair of wires, such as in a lamp or zip cord, each side "sees" a slightly different value (in amplitude, phase, or both) and thus that difference can be sensed by the receiver as desired signal instead of noise. If you twist the pair, then at wavelengths (within a factor of 2 or so) longer than the twist, both sides of the cable "see" the same noise signal, canceling the noise. In a coax, the outer shield is (assumed to be) a perfectly-conducting solid "ground" so any noise signal hitting it is equal all the way around, and does not generate a difference signal to the center conductor that can be detected as a desirable signal. That makes coax more resistant to coupled noise.

Note twisted pairs for signal transmission are not uncommon, with tighter twists (more turns per inch) providing higher frequency noise rejection. Twisted pairs also increase the capacitance per inch, outweighing the additional length, and thus exhibit lower impedance than parallel wires.

Coax is cheap in bulk, and is required for most digital and RF signals, so it is more cost effective for manufacturers to stock coax that they can use for everything in their systems. Power cables and speaker cables carry very high-level signals and are driven by low impedances so rarely couple noise, thus simple parallel wires are adequate in consumer installations. You do find power cables are often twisted, however, as much to (probably more to) reduce their noise radiation into other components as for rejection of noise impinging upon them.

FWIWM - Don

 

[Doodski]

Each has it's qualities. The Lab was a scalpel in hoisting operations, The Cormorant is a broadsword. The Cormorant has longer legs, which is important in this country.

The Lab was steam driven, the Cormorant was like stepping on to the bridge of the star-ship enterprise. Pilots had to actually fly the Lab everywhere, so their hands and feet skills were superlative. Cormorant has multiple automatic flight systems, so those skills deteriorated a bit in the corps.

Which is better? Cormorant is better for getting there, Lab is better when you are actually there. So meh, take you pic.

Lab 305 blew up in mid air from an engine fire/fuel dump and killed 6 of my brothers returning from a mission, Cormorant 914 hit the water on a ship hoist and killed 3 of my brothers.

914 messed me up for a while. I was supposed to be on that crew and a last minute schedule change put someone else on it. Lots of survivor guilt to this day. Guilt doesn't make any sense because it wasn't my fault it hit the water nor why I wasn't on it, but the mind/emotions can be a wacky thing sometimes.....

Those are interesting analogies for each. You did your best and that was a huge contribution and a lot to give...

 

[flightops]

Simple handwaving non-rigorous explanation:

If a signal (e.g. noise) crosses a parallel pair of wires, such as in a lamp or zip cord, one side "sees" a slightly different value and thus that difference can be sensed by the receiver as desired signal instead of noise. If you twist the pair, then at wavelengths (within a factor of 2 or so) longer than the twist, both sides of the cable "see" the same noise signal, canceling the noise. In a coax, the outer shield is (assumed to be) a perfectly-conducting solid "ground" so any noise signal hitting it is equal all the way around, and does not generate a difference signal to the center conductor that can be detected as a desirable signal. That makes coax more resistant to coupled noise.

Note twisted pairs for signal transmission are not uncommon, with tighter twists (more turns per inch) providing higher frequency noise rejection. Twisted pairs also increase the capacitance per inch, outweighing the additional length, and thus exhibit lower impedance than parallel wires.

Coax is cheap in bulk, and is required for most digital and RF signals, so it is more cost effective for manufacturers to stock coax that they can use for everything in their systems. Power cables and speaker cables carry very high-level signals and are driven by low impedances so rarely couple noise, thus simple parallel wires are adequate in consumer installations. You do find power cables are often twisted, however, as much to (probably more to) reduce their noise radiation into other components as for rejection of noise impinging upon them.

FWIWM - Don

Thank you. That was both interesting, informative and easy to digest.

 

[flightops]

Those are interesting analogies for each. You did your best and that was a huge contribution and a lot to give...

we all do what we can.....

 

[Chrispy]

@flightops great posts about your flight expierences....hope you don't get recalled to fight the orange one.

 

[Doodski]

we all do what we can.....

We do and in your case you gave more than most. So do you still fly at any capacity? Recreationally etc?

 

[DonH56]

p.s. My brother was a Blackhawk medivac pilot, also doing some support runs and at the end of his NG days drug mitigation runs (where he says he was shot at more in the USA than combat medivac missions), but other than getting to look in the chopper I know nothing about them. Respect for your service!

He's been a commercial airline pilot for a long time now, hoping to retire in a year or two.

 

[flightops]

We do and in your case you gave more than most. So do you still fly at any capacity? Recreationally etc?

Nope.

Feet will never leave the ground again. Not even on an airline.

Figure I've used up all my luck. Lost track of how many times I was sure "this is it" and not a damned thing I can do about it.

Miss it infrequently, but I've got the memories and I know I've seen and done things people can't even imagine.

Saved lives, so many I just stopped counting at some point.

Also stopped counting the number of recoveries.

so there's also some memories I'd rather not have.

I still remember the newer guys asking me how many missions I'd flown, how many this, how many that and replying "I dunno, that sounds about right". We're a small community so I'd talk with those guys again later on and they then understood what I meant with "I dunno"......

So it's about a draw overall.

Between the pension, the disability insurance, CPP-D and VAC, I'm pretty well taken care of. I'm classified as "125% disabled" by VAC. That's where they stopped because i jst got tired of describing more service injuries. Once you're over 100% it doesn't matter anymore anyways. Medical is also covered until the day I die. My "income" is right about what it was when I was flying, and it's like that until I hit 70, and then it drops to full pension rates, plus insurance, plus CPP-D. All indexed to the COL each year. So no financial stresses to deal with. That's something at least. I was also always smart with the money, so no debts whatsoever and about 55% left on the mortgage. Cars are new, so good there. We pay cash when we buy them. Have so much money put away in RRSP's I dont think we;ll ever get the tax break when pulling it out Stopped RRSP's years ago and have been pounding the TFSA's. Like I mentioned, we were/are smart with the money we did/do get.

Still, it all comes out about even.....I don't even know if I'll be able to walk that day until I wake up and my legs will move. Then it's dealing with pain all day until sleep. Broken neck, broken back, both knees blown out, shoulder blown out, probably looking at a hip replacement in a few years, every joint, muscle and tendon has been torn at some point...constant physio for everything, have my own traction table at home, etc, etc. I wake up in the morning and note the pain level, set that as baseline for the day and ignore it unless something begins to hurt worse, then I know it's something I need to pay attention to.

SAR is all or nothing.

Give till it literally hurts and then dig deeper......

 

[mhardy6647]

Twisted pair works fine for line level signals (unbalanced) -- even when taken to rather absurd extremes.



These are made from 30-ga enamel insulated magnet wire from Radio Shack.

 

[Doodski]

Nope.

Feet will never leave the ground again.

Figure I've used up all my luck. Lost track of how many times I was sure "this is it" and not a damned thing I can do about it.

Miss it infrequently, but I've got the memories and I know I've seen and done things people can't even imagine.

Saved lives, so many I just stopped counting at some point.

Also stopped counting the number of recoveries.

so there's also some memories I'd rather not have.

I still remember the newer guys asking me how many missions I'd flown, how many this, how many that and replying "I dunno, that sounds about right". We're a small community so I'd talk with those guys again later on and they then understood what I meant with "I dunno"......

So it's about a draw overall.

Between the pension, the disability insurance, CPP-D and VAC, I'm pretty well taken care of. I'm classified as "125% disabled" by VAC. Medical is also covered until the day I die. My "income" is right about what it was when I was flying, and it's like that until I hit 70, and then it drops to full pension rates, plus insurance, plus CPP-D. All indexed to the COL each year. So no financial stresses to deal with. That's something at least.

Still, it all comes out about even.....I don't even know if I'll be able to walk that day until I wake up and my legs will move. Then it's dealing with pain all day until sleep. Broken neck, broken back, both knees blown out, shoulder blown out, probably looking at a hip replacement in a few years, every joint, muscle and tendon has been torn at some point...constant physio for everything, have my own traction table at home, etc, etc.

SAR is all or nothing.

A intense life full of excitement and being tested to the maximum and more. I hope you have a very good retirement life, enjoy your days in peace and appreciate knowing that we really appreciate your selfless contributions to society. With that I must go grocery shopping and I hope to see you contributing here @ ASR.

 

[flightops]

Twisted pair works fine for line level signals (unbalanced) -- even when taken to rather absurd extremes.



These are made from 30-ga enamel insulated magnet wire from Radio Shack.

well that's interesting......

 

[flightops]

I've got about 600 feet of 12 gauge speaker wire laying about here:

And about 40-50 spare solder-on RCA ends.

I think I'll try a simple flat wire rca interconnect and then twist one with the vice and cordless drill.

Just to see what happens when used as interconnects. It's a "curiosity killed the cat" type of thing.

I've got one run that's roughly 15+ feet long. That should be a good torture test......if noise doesn't show up there, it seems likely not to show up anywhere. ....

 

[MaxwellsEq]

if noise doesn't show up there, it seems likely not to show up anywhere

The ideal approach is to minimise noise entering into your system at every "porthole". It's helpful to understand that there is noise heading towards your portholes that you can hear such as hums and buzzes (usually to do with mains electricity); there are "splats" from switches, refrigerators etc; there is also noise heading towards the portholes that you can't hear, such as radio frequency noises from WiFi, radio/TV towers etc. Because you can't hear these noises, you may assume that everything is OK, but it's not. The radio frequency noises can cause the input circuitry just inside the porthole to be overloaded or to resonate, which can reduce the quality of the performance. In these cases, your ears may not be sufficient to check what's happening and you may need test equipment.