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Just wondering what everyone use's for their internal wiring inside Amp?

Discussion in 'Home Brew' started by ElectronTubesRule, Oct 2, 2011.

  1. ElectronTubesRule

    ElectronTubesRule Active Member

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    I have some Belden 8866 that is old scrap from when I worked in Telcom industry. So I am going to use it to make my test leads for my 5000V Multimeter set up. I only have enough to make the leads. I am guessing that unless things have changed in the last 10 years you have to buy 100 feet minimum from most supplier.



    8866 is gross overkill for an amp that will never see ac/dc power above 2700V and never more then 1 amp since it is rated to 40KV. So what do most of you guys use for your HV hookup's inside the amp? Also where is the best place to by small amounts as in under 100feet? Do you go with shielded?If so braided shield or foil? Do you go with high tech high insulation materials or just regular stuff. Would I be right to assume that copper conductor is the norm? I ask because I know that aluminum and nicrome are less like to pick up stray rf, less likely to resonate and introduce parasitic's and are cheaper then copper.....Although the copper market recently corrected itself. Since we are not talking about residential wiring their is nothing barring the use of things like aluminum. Also since space is tight and we are talking about low total volume of wiring in terms of length nothing preventing one from using more expensive Teflon insulation to reduce the thickness of the jacket and make routing easier and still have excellent insulation properties, good resistance to heat and environmental factors as in non-reactive to most industrial solvents and acids in normal concentrations seen in field environment.

    No one really mentions conductor material choices, insulation choices, types of shielding and why you may or may not want to shield various power lines etc.....

    Given that HV is a beast of a different color compared to anything else most people will wire I thought it merited some discussion as to what you use and why?
     

  2. ElectronTubesRule

    ElectronTubesRule Active Member

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    What are your thoughts on XLPE HV wire? I have a friend that wants to unload some 5000V Single Conductor XLPE wire. I have never used the HV XLPE wire but I have seen the low voltage XLPE wire fail badly due to hydroscopic nature. I have heard that the HV variety is not as failure prone. All I know about this stuff is it is left over from rewireing the landing lights and taxi way lights at the local comunnity airport. 90 C continuous 5000V continuous 250C temp. for short circuit.

    I am bit nervous about using XLPE but I have never used it in a nice dry box that will be inside of a controlled environment with climate control. I have seen the low voltage stuff fail and tree or spider web from moisture intrusion. I know XLPE has been used in coax for a long long time. Just thought I would ask how it holds up inside a hot box with lots of RF,AC and DC energy rushing through it and around it and such? It is dirt cheap and has a voltage rating that is fine for the ac and DC voltages in the box.

    I have not ruled out PTFE, Silicone, Rubber or Multiple insulation layers and materials. I have looked at everything and I am pretty sure I do not not need to shield anything not using coax inside of the amp. is this a fair assumption.

    To be honest I would like to find a good price on silicone insulated hook up wire. I had a 1986 Toyota 4Runner that came with silicone hoses and boots on a lot of key parts....... All the parts that had silicone boots where just as soft and supple 17 years latter. The rad hoses lasted a long long time and the hoses on that where vacuum lines where about 98% original 17 years latter. So while I have never used silicone jacketed hook up wire professionally or for a project I like how well it held up as hoses and boots on my old 4Runner. Really impressive life cycle. It was my Dad's before it was mine.

    Opinions? Idea's?
     
  3. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    My opinion is that you are over-complicating things too much. My idea is that you can use RG-8 coaxial cable with the solid polyethylene insulation (NOT THE FOAM!!) as HV wire either with or without the shield. If you use the shield make sure it is well dressed on the end and at least a full inch or more from the end of the cable where the HV is present on the centre conductor. I know many homebrewers that have used this on their 813's or 3-500Z's. IIRC it is good to 5 Kv or more.
     
  4. olegtf

    olegtf Member

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    Just regular spark-plug wire, how about that?
     
  5. mackmobile43

    mackmobile43 Jock Supporter

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    I use surplus silver coated Teflon wire bought on the cheap at ebay.
     
  6. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Most spark plug wire has far too high resistance to be used as the plate wiring.An amp draws far more current that a spark plug and the voltage drop of the wore is too much.
     
  7. office888

    office888 Active Member

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    Follow the examples of hams back in the day and use whatever is available.
     
  8. JoeDirt

    JoeDirt Well-Known Member

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    You can buy high performance spark plug wire with really low resistance. I bought a roll of MSD that had around 50ohms per foot.
     
  9. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    So figure about two feet for a mid sized amp. That's 100 ohms. At a plate current of 0.5 amps that two feet of wire will dissipate 50 watts of heat. Sounds like a house fire waiting to happen. We won't even think about what it will do with a big tube drawing about an amp of current. 100 watts is a bit much for a piece of wire don't you think?
     
  10. kc8adu

    kc8adu Active Member

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    +1
    only 2 places anything special would be needed is plate supply (high voltage).
    and in the transformers which use silver/ teflon.
     

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