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    VTA ST 70 20 AWG tinned copper core wire question

    Midwestside
    Midwestside

    Posts : 9
    Join date : 2019-03-20

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    Post by Midwestside on Wed Mar 20, 2019 7:15 pm

    Hello, new here, first post.

    Like the heading states, i am curious about the rating of the red 20 gauge hookup wire that comes with the kit.
    Is this just standard tinned copper core wire i can pick up at an electronics store or is there a special heat rating?
    I may need to re route some wires and thought to ask about this.
    PeterCapo
    PeterCapo

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    Join date : 2008-12-05

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    Post by PeterCapo on Wed Mar 20, 2019 7:24 pm

    Copper wire is fine but with insulation that won't melt too much where the connection is soldered and make a melted cheese sandwich out of your wiring, like PVC insulation can.  I think Bob uses a kind of wire with a higher temperature rating for the insulation, but I do not recall what it is called.  Perhaps he will offer some specifics.

    Otherwise, you'd want to make sure the voltage rating for the insulation is sufficient for the level of voltage expected on the wire.  I'd think a 600VDC rating should be fine.
    Midwestside
    Midwestside

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    Join date : 2019-03-20

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    Post by Midwestside on Wed Mar 20, 2019 7:53 pm

    Thanks Peter,


    If someone has a better suggestion, im all ears.

    I'm looking at something like this.
    Looks like I'm too new to post a link.
    Its ebay item # 321267925529
    Remmington Industries 20 AWG Gauge Stranded Hook Up Wire Red 100 ft 0.0320" UL1015 600 Volts
    PeterCapo
    PeterCapo

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    Post by PeterCapo on Wed Mar 20, 2019 8:00 pm

    Again, and unless someone feels differently, I'd avoid garden variety PVC insulation.

    Teflon insulation is great but harder to work with: https://www.tubedepot.com/products/20-ga-silver-plated-aerospace-grade-ptfe-wire?taxon_id=103
    Midwestside
    Midwestside

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    Post by Midwestside on Wed Mar 20, 2019 8:07 pm

    Peter,

    Even better!  I wasn't having great luck searching on my own.
    PeterCapo
    PeterCapo

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    Post by PeterCapo on Wed Mar 20, 2019 8:13 pm

    Hope this link works... https://www.mouser.com/Wire-Cable/Hook-up-Wire/_/N-5ggs?P=1yx5jmeZ1z0x8gxZ1z0wxeo

    You'll want to look at the datasheets or otherwise look these up to find out about the various temperature ratings for the insulation as well as their voltage ratings. Actually I think they are all either 600VDC or 1KVDC.
    Midwestside
    Midwestside

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    Post by Midwestside on Wed Mar 20, 2019 8:23 pm

    I can go with the wire at tube depot, its 600v, plus looks like i can load up on a few other things Very Happy
    Peter W.
    Peter W.

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    Location : Melrose Park, PA

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    Post by Peter W. on Thu Mar 21, 2019 9:53 am

    https://www.mouser.com/Wire-Cable/Hook-up-Wire/_/N-5ggs?P=1yx5jmeZ1z0jnf6Z1z0juksZ1z0xfpoZ1z0x8gx  

    More than $0.20 per foot is just plain nuts. At $1.90, even more nuts.

    Some basics about wire:  

    a) The OEM Dynaco products came with vinyl-clad, tinned solid 22 gauge wire for the most part. And for the most part, that will do fine in most applications.
    b) Yes, vinyl insulation will turn into a sticky mess if not soldered properly.
    c)  Because 1. The iron is too cold & 2. the solder in use is not a Eutectic mix & 3. the proper technique - what to heat first - is not being used.  One, two, or all three.

    There is no need for boutique wire. Mil.Spec. wire is fine, and will very certainly serve the purpose if one wishes to use a belt, suspenders and Velcro. BUT! Two things about PTFE insulation:

    i) It requires a very sharp stripper so as to cut the insulation but not nick the wire.
    ii) PTFE in the environment is very nasty.  And if burnt, even small exposure to vapors will kill birds and damage cats. So, save the cuttings and dispose of them so that they will not be burnt - such as in trash-to-steam.

    A few more things, while I am on this particular path:

    Insulation ratings were created for raceways, conduits and point-to-remote-point wiring conditions. Not for internal wiring within devices. And the point of all of it was so that wiring carrying a high voltage would not cross into a lower voltage line within that conduit or raceway.  Now, with that in mind, consider that the typical tube amp has operating voltages from 5 V to ~500 V. with the base of the rectifier tube carrying both 5 V and ~350 V. The potential fault here will be more towards a solder bridge than an insulation failure (vs. melt-down).

    Which leads to a real concern I have with stranded wire in such applications. A loose strand could cause genuine havoc.
    Which leads to a real concern I have with solid wire - especially wire that is not properly annealed prior to insulation. Even a small nick during the stripping process could cause a weak spot that could fail subsequently.
    A perfect example of not being able to have it both ways. Writing for myself, I prefer solid wire (and very sharp strippers), and why I advocate checking _EVERY_ connection when taking on a new-to-me piece of kit.

    NOTE ALSO: Wire colors have meaning. Mixing metaphors can be dangerous.  https://www.radioremembered.org/xfmr.htm   Try not to use a wire color that does not, at least, resemble what its common use meant 'back in the day'. Using white or green wire to carry active current is a bad idea, as both colors have specific meanings (here in the US anyway): White = neutral or return, Green = Ground. AND! All secondary windings on transformers carry current, which is why you will never see an RMA-compliant transformer showing a green lead - unless it is to the shell - not uncommon. For our Euro friends - here are all the color-codes rolled up:  https://www.allaboutcircuits.com/textbook/reference/chpt-2/wiring-color-codes/  

    What all this comes down to is: Be careful out there!   There is no rush, and whereas there is always time to 'do it over', that very nearly always takes longer than doing it right the first time. And, if technique is important, skills applying said technique comes with time and practice. Give yourself the time until it becomes second-nature.

    Enjoy!
    Midwestside
    Midwestside

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    Post by Midwestside on Thu Mar 21, 2019 9:30 pm



    Wow Peter, thanks for the trove of information and history here!

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