Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: EKDENTON on June 20, 2018, 04:33:23 pm
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Does anyone know if the hookup wire here at hoffmans the awg18 a high voltage high heat resistant type?
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not sure what your building, but I'm pretty sure there's many, many >5yr old amps with miles of Doug's wire making 'em work just fine.
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600v rated wire is not too common, and the only place I've bought it was Mojotone. It was cloth-jacketed and looks similar to what Hoffman offers. Because cloth-jacketed wire is a bit specialized for building a certain style of tube amp (and comes at a premium price), I'd say it's likely rated for 600v.
Myself and others, including commercial amp companies, have used 300v wire without trouble. I wouldn't strongly recommend it (I don't know how safe it is) but that is true.
In terms of heat tolerance... how much heat are you talking about?
A soldering iron will melt or burn any insulation I've ever encountered. I've melted "normal" plastic wire by direct contact with a vacuum tube, while some silicone wire is rated to 200C and wouldn't have melted. But it shouldn't have been touching the power tube in the first place... just being in a hot chassis near resistors and stuff will be fine for any wire.
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You don't need a 600v rating on hookup wire
But, I am stocking Teflon 20 ga, silver plated copper wire in 5 colors
It has a 600v rating and 200C temp rating
It's on this page.
https://hoffmanamps.com/MyStore/catalog/WireCableMobile.htm
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The 300V rating is very conservative. And 300V _testing_ is the highest normally done in general wire making.
300V will not jump a coat of paint. All hookup wire insulation is much beefier than paint. We insulate for mechanical damage, not raw voltage.
If you are stuffing a lot of wires real tight together, conduit and such, and a breakdown would be dangerous to people, you MUST get your insulation rated for your voltages. If you are open-wiring such as a chassis, bare wire would almost work except for vibration.
Only a few places in a g-amp exceed 300V. The two HV AC lines to each other. The two plate leads to the OT. And most of your B+ run from first to last filter cap. With unlikely exceptions, all your small-tube plates actually sit under 300V, and everything else even less. The transformers usually come with ample leads for the voltages they deliver. The B+ is often run alone. But even if you bundle it with the ground, you have _two_ 300V-rated insulations between conductors.
Any place any sort of power wire has to go though a metal hole, use a good grommet. (You know where to find them.)
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Teflon is great stuff in military and aircraft specs, but in g-amp practice it is a total pain to strip. And a halfast strip-job nicks the copper and it will eventually break on the road. There are techniques and tools. If you are into fine fiddly tools you can find the tips. Personally I'd rather use good PVC and good ordinary strippers.
The true cloth push-back wire has no trustworthy voltage rating because the cloth weave is not 100% perfect and there could be a "thin" spot. I've seen thousands of feet installed over 50++ years and you just do not see problems with that.
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yes, all that PRR said :icon_biggrin: