Hook up wire for tube gear

[My3gger]

I'm out of hook up wire, mostly for tag board connections, XLR phantom returns and parts of psu (ground wire which is cloth cowered or non insulated). Shielded or other signal runs are made from thinner multicore wire which i still have.
Old wire had diameter with PVC jacket of about ~1,5mm, looked very similar to this one:

http://www.tasker.it/db_files/products/4e6be8e079.pdf

Core has 22AWG which should be enough, i can get it localy and is cheap.  The only thing i'm not sure about is max 49V. Datasheet doesn't mention at what current, AC or DC. Any thoughts on this? Tasker C110 is comparable to wire that worked well for years, so i don't see problems with it. Thanks.

 

[weiss]

I'm interested in this question as well. how are the possible voltages being calculated?

 

[john12ax7]

Don't use low voltage wire for tube amps. Not sure of the exact calculation, but the insulation resistance will not be sufficient.

 

[My3gger]

There are online formulas for calculation of wire's max voltages. Part of the problem is EU sellers like Tube-Town, Banzai, Muzikding and similar don't specify max V or insulations type. Makes me wonder how many tube build have insufficient cables...

I'm using mains 300/500V wire from IEC to psu (HV connections on psu with same wire) and then to p2p board. Heaters are connected with the same wire twisted, going from psu to tube sockets, grounds 18-20AWG solid wire without insulation. All of this is cheap and comes in different colors, so no problem. I tried PTFE (teflon) which is hard to strip, it tends to bend like spaghetti... CJ had similar comment, i would add cloth covered wire now comes in different gauges from most places:
https://groupdiy.com/index.php?topic=35826.msg439825#msg439825

The only place i would prefer thinner wire are connections on (pre)amp p2p board/board to tube sockets. Like anode, G2, sometimes decoupling and similar. I will report back Tasker and Farnell tech support for solutions, other comments from here are very welcome.

 

[scott2000]

I'm happy enough with the 600v mil spec teflon stuff....... 22awg/20/18........

No issues stripping here??? Using just some plain Torvaal stripper I inherited from my step father....

 

[PRR]

> formulas for calculation of wire's max voltages.

*Current*. Not Voltage.

The deal is: testing is expensive, few buyers need high voltage, so a lot of no-voltage wire is sold.

A coat of paint will stop 300V. We normally have much more insulation than that for mechanical reasons.

When you get to the 600V on high-power tube output stages, you can use the wire designed onto the OT and PT. Also these leads should be mostly "air insulated", not touching other wires or chassis.

Old appliance wall-cords will be good for 600V (even in the US).

 

[john12ax7]

Run of the mill hookup wire  is often 300V. But 600V is also very common,  and easily purchased from the big distributors, and also tube shops here in the US. Maybe someone has more info on EU sources? For sure someone like Farnell would have it,  the advantage of smaller shops is you can often get smaller quantities if needed.

 

[Tubetec]

I found some stranded tinned wire with impregnated textile insulation , works very nice if you put a bend or a turn in it it stays where you want it too , always makes a nice quick solder joint with minimal dwell time , I hate the way regular plastic turns crusty near the solder points . I do have a small reel of silver plated ptfe insulated stuff , its not my favourite to work with but its probably about as good as you can get electrically . Ive been meaning to buy up some space grade wires ,I often see bundles of ex Nasa stock on ebay ,out of Huntstville Alabama , seems like great value mostly silver plated Ptfe insulated .

 

[moamps]

Maybe someone has more info on EU sources?

keywords are H05 for 300/500 and H07 for 450/700
https://www.tme.eu/gb/katalog/#id_category=38&search=h05&s_field=artykul&s_order=ASC&visible_params=2%2C529%2C661%2C2517%2C663%2C665%2C673%2C32%2C657%2C18%2C669&used_params=2%3A45188%3B

 

[weiss]

Is there a way to recognize insufficient cables?

 

[boji]

Is there a way to recognize insufficient cables?

+1 on that.  Non-tube aside:  I've been using Chinese ribbon connectors for low voltage, the ones with the pre-terminated dupont ends, but I don't trust the insulation will stay flexible after a few years.  Also don't think there's much copper in the wire.  :

 

[john12ax7]

Some wire will have the specs printed on the jacket,  or at least the model number so you can look up the specs.  Without anything I would set it aside for non-critical low voltage low temperature applications only.

 

[merlin]

I've never even heard of 7/0.2 PVC wire rated for less than 300V. I think you're worrying about nothing.

 

[Tubetec]

Working in electrical and motors Ive seen wires and insulation completely degraded , burnt up from too much current , under normal usage in tube amps its probably never going to happen ,  the wire leads out of motors use high temp rubberised 400v 200C flame retardent  cables ,but thats a very extreme environment compared to a tube amp .

The only time I saw wire insulation in a tube amp fail was a Peavey valve king , HT supply out and back to the standby switch passed very close to a large resistor which supplied the screens , the wires must have shifted ,made contact with the resistor and melted and shorted , piles of noxious smoke when it happened during a gig , but other than that just a new lenght of cable re routed away from the heat source fixed it .

On a few ocassions I found internal wiring with rubberised insulation that had completely degraded almost decomposed including the copper itself , there was a known problem with some substandard wire produced in Italy in the 60's , that was used in Binson's Echorec .                                                                                                                         

 

[weiss]

Thanks for the input!

 

[Tubetec]

I kinda like the idea of plain  copper threaded through the coloured fibre tubing  , means you can choose the most suitable diameter
from a pile of off cuts of electrical installation wire ,  cut it and the insulation(colour coded if you want) to lenght without the need for  a stripping tool . Its quick and easy a gives a nice vintage hand wired appearance . The high temp nature of the fibre means even if your amp starts to meltdown the insulation still remains good ,
There a soft silicone covered fibre braid insulation at work ,its better than the ordinary stuff by a long way , soft, supple and with a wonderfull glossy appearance ,it all adds a touch of class even if its just to tidy a bunch of plastic coated wire going around the chassis . I might add in a spool or two of it to my order ,once I get a trade name I'll post it here for reference .
One version is scarlet red , almost kinky in appearance , the others a light beige and a deep green colour , similar to the pic below .

 

[My3gger]

> formulas for calculation of wire's max voltages.

*Current*. Not Voltage.

The deal is: testing is expensive, few buyers need high voltage, so a lot of no-voltage wire is sold.

A coat of paint will stop 300V. We normally have much more insulation than that for mechanical reasons.

When you get to the 600V on high-power tube output stages, you can use the wire designed onto the OT and PT. Also these leads should be mostly "air insulated", not touching other wires or chassis.

Old appliance wall-cords will be good for 600V (even in the US).

Btw, this is quite similar reply to another from years ago, it was about "usual blue" 0,6W metal film resistors. Manufacturers often only meassure up to certain voltage, although they work well at higher voltages if max power is not exceeded.

Farnell and local shop suggested using higher cross section when one needs 300/500V stated in datasheet.

I like idea of using PT/OT external wires for psu at HV/HP connections. Local toroid winder offered them with many typical colors at very low prices, compared to EU shops for this things. They are just right also having flame retardand pvc insulation.
Can't find what is "air insulated", probably hanging in air not being twisted or touching anything. Heater wires in PT here are often hefty solid core insulated with insulation as shown by Tubetec:
https://groupdiy.com/index.php?action=dlattach;topic=72131.0;attach=66734;image
I used a lot of PVC ins. wire on p2p boards-tube sockets, similar to Tasker C110 or other cables (also insulation as on Tubetec's pic) from known European manufacturers. Insulation doesn't become brittle with time, stays where it was from beginning, short don't leave any marks on it. Burns can be avoided by making 180 degree hook, as shown on youtube videos or books with old US army courses for p2p wiring. I might find this in my files if needed...

Is there a way to recognize insufficient cables?

I avoid hook up wire with thin solid core and insulation. Pvc insulation on spool of such ~ 10 years old  unused wire became very brittle, it is hard to cut off insulation without damaging tinned copper core, so i never used it and thrown away all of it. Didn't trust it for any use, was bought from Banzai having same diameter looking like this:
https://www.banzaimusic.com/Wire-SC-0-5-red.html

 

[PRR]

> Can't find what is "air insulated",

My neighbor just put in a half-mile of 20,000 Volt power line. The conductor is bare steel. At that voltage, insulation is dubious. When overhead (10 meters up) installation is practical, usually they don't even pretend to insulate. Make sure it can't touch anything which can't stand the voltage. (This line is on large ceramic pots on wood poles.)

 

[boji]

Just wanted to say thanks Tubetec, I will have to look into that cloth braiding.  Insulitherm is one brand that looks decent.
I have power and such to distribute around backplanes and like the idea of making clean, trace-like runs, then covering them afterwards to suit.

 

[Tubetec]

Cheers Boji ,
your spiritual, emotional and technical contributions  havent gone unnoticed either , Im sure of that .