Strike a Solder Joint Behind Enemy Lines
hackaday.com
hackaday.com
To solder a splice - 1) strip both conductors to be soldered about 1/2" and form a loop on one. 2) Stick the second conductor through the loop formed in the first and bend a loop around to join the wires. 3) Cut or break about 1/2" of solder/flux and lay on something flat, clean, and hard - 2 out of 3 is good enough here. 4) Use a hammer, flat rock, end of pocketknife, etc to flatten the solder until it is about 1/8" wide and maybe twice as long. 5) Wrap the flattened solder around the loops so that the join is covered by solder. 6) Strike a match, use a lighter, a torch, etc to melt the solder and flux into the joint. 7) Cover with weather-tight electrical tape and go on about your business.
It never failed for me.
If mechanical splice connectors had been used then each cable would have a section which was much larger diameter than the unspliced cable diameter and if you didn't match the curl in the cable when you did the splice it would make the cable hard to roll since the coils would not lay flat. Some cables might accumulate multiple splices before aging out of the inventory and all those fat splices would make it hard to deal with very quickly.
The idea here is to produce a taped and sealed splice that has a final diameter that is as close to the unbroken diameter as possible so that there is nothing for the cable to hang on if it has to be pulled or dragged across the terrain or some machinery. Crimp splices, especially if you have multiple conductors cut will always produce a section of the cable that has a much larger diameter after splicing than the original cable and will be less flexible and therefore harder to deal with in the field. Any time you have a guy trying to shoulder or neck roll a cable that weighs more than 100 pounds you need to avoid complicating things.
When we did multiple conductor splices, up to 96 channels in my own experience, we had boards that were notched for each conductor pair and they were color-matched and spaced so that the entire splice would be a little under 2 feet long (.6 m) and all of it was looped and soldered. With a breakout box we could check continuity on each channel (a standard daily test) and have confidence that the splice was good before deploying the repaired cable.
I guess the easy answer is that you worry less about cracking solder than you do about being able to use the repaired cable as if it had not been damaged. Since each individual repair affected only an inch or so of the cable it had little effect on your ability to reuse the cable after the repair. The whole taped repair on a single conductor could be less than 2" long and would have a wrap of self-sealing rubber tape and a swipe with liquid tape to seal the ends. Very durable for all those chewies that cattle, deer, marmots, mice, etc. would add to your gear if it sat around in their neighborhood long enough.
I hope that explains it. By keeping the diameter of each repair near the diameter of the unbroken wire and spreading them along the cable if there are multiple repairs, the overall diameter of the cable ends up close to the unbroken diameter and the natural coil of the cable is unaffected.
They take their time. Shots linger, no jump cuts. No-one is driving around while talking, interspersed with random unrelated scenery shots. There are periods of silence.
At least on TV, most documentary style shows try to be so flashy and "cool", with lots of unrelated content that serves no purpose except to make it harder to think about what is being conveyed.
A twist or knotted joint is obviously fast and simple. But in the wrong environment it will degrade quickly. Are you laying a charge to be blown in five minutes, or laying buried communication lines to use for six months?
You know, that would be a great way to fix most intermittent headphone problems, where you mainly need a strong mechanical result as much as the electrical connection.
On exercises it was our job to provide communications and quite often we would lay miles of copper wires in the woods for the field telephones and join the wires together with these devices.
The black powder is some kind of thermite I think - lighting it would melt the solder in the copper tube, you'd push the copper wires you'd pre stripped into it and you'd hold it long enough for it to solidify, which was sometimes long enough to burn your fingers!
In the UK in the 80s the CCF had lots of surplus WW2 equipment. Beautiful valve radios and classic 303 rifles!
I believe that it quite improbable that it was thermite, probably gunpowder with some additives (maybe a pinch of magnesium?)
Excellent point, hadn't thought of that.
The Germans were the first army to have radio on every vehicle, sometimes 3 for higher ranks. It was handy on the go, but leaked intelligence like a sieve when stationary for days, and the Germans were overconfident in its secrecy.
The British were warned of air raids even before takeoff because German pilots followed a procedure of testing their radio on the ground.
The mastermind behind the British effort built a similar system, but global, for the US, after WW2.
SR-71 flights initially used radios, but since Russian "trawlers" were tracking the broadcasts, later flights, including multiple refuelings, were done in radio silence.
WWII version of metadata collection
Of course what had happened was that there were two parallel earth return phone lines on either side of the front, the lowest impedance path used both .....
Now this story was told to me by some old timers (people who could talk to you at the same time as they held a conversation in morse) - they told some great stories (all that I know of were true) - take it with the appropriate grain of salt
There's a pre-made fitting (H cross section) which has solder rings inside. You press the pipes in and heat it until the solder comes out on both ends.
The technique needs an external source of heat but that's not generally a problem in civilian plumbing.