Heater wiring wire question.

[Champ_49]

Sorry. This might be a stupid question..
I got some pvc wires from hoffman. 18 awg Stranded and 20awg solid.
the pvc coating on the wire says 300V  for even the 18awg. Is this ok to use for heater wiring? I always hear heater wires should be at least 600V For the power tubes at least.
I'm assuming you can. But just wondering why it says it's rated for only 300V? Is this only when the temp gets high enough that it turns to a rating of 300 V Under high temp conditions?
And also does the actual pvc  jacket (thickness?) On the wire affect the voltage rating?  I always thought that 18awg is always rated for at least more than 600V Regardless.

Another thing I found interesting  was almost all stores that sell tube amp wires don't have
The solid core heater wires for 18awg. Or I can't seem to find them. Solid core would in fact I think be easier to work with because they stay in shape and you can get them into the preamp tube pins easier. Although they can only be bent a limited number of times before they break. Stranded sometimes can be difficult to get through the preamp tube pins.

How do you guys do it?

[tubenit]

I always hear heater wires should be at least 600V For the power tubes at least.

Why would you need 600v wire for 6.3vac heater voltage?

Use the 18 gauge stranded wire for power tubes.  Use solid or stranded 20 gauge for preamp wiring.

Doug's wire is fine.  I've used it for many years on many amps with absolutely NO issues or concerns at all.

With respect, Tubenit

[Mike_J]

The problem with using solid core wire for the preamp tubes is it can not take much bending before it breaks.  This happened to me.  I was working on the preamp wires and had to bend the solid core heater wires to get the work done.  The amp made no noise after the work was completed.  Eventually I noticed there were no lights on in the preamp tubes and found the break in the heater wire.  Problem fixed.

Sluckey had a good suggestion that I have used ever since with success.  Just put a little solder on the stranded wire and make sure your preamp sockets have slots large enough to insert the wire through.

Thanks
Mike

[jjasilli]

I've used solid core wire for heaters; two colors twisted in an el drill.  It stays twisted, and exactly where you put it. 

[PRR]

> I always hear heater wires should be at least 600V For the power tubes at least.

Where do you "always hear" that? On the Innernet? A million monkeys on a million typewriters should post some different bumph some times.

The heater wires have 6V-7V between them and zero to 50V to-ground. We usually route them well away from other wires/pins because we don't want heater current hum sneaking into our precious audio.

> I always thought that 18awg is always rated for at least more than 600V Regardless.

Does not compute. Gauge, copper-fatness, has *nothing* to do with the voltage you can run it at. Voltage breakdown is all about the rubber you wrap it in. Wrap #18 in super thin paper, you may have trouble at 100V-200V. (Paper-wrap cable was used a LOT in early telephone systems, the ones that went-out when it was raining somewhere.) Gauge is an indication of the *current* it can pass, for a certain temperature, usually limited by insulation softening, also affected by how well the heat can get away.

It says "300V" because 300V is the standard test for 120V/240V wiring, which is made by the millions of miles. Anything else is High Voltage testing, which costs a LOT more.

The "300V" rating is VERY conservative, worst-case, and also a Standard Test. A "300V" rating does not mean that at 301V it blows-up. I would use that stuff fearlessly everywhere in a 450V B+ amplifier. Even the power plate leads which kick-up to over 800V. Only in the obscenely over-volted amps (580V Ampegs, 610V Bogens) would I worry; however the OT plate wires *are* engineered for the stress.

[labb]

The voltage rating on connecting wire is the rating of the insulation of the wire. ie: the voltage at which the insulation may break down if the wire is in close proximity  to another element. I would have to agree with PRR that the 300 volt rated is good for most amps we build. Personally I use the 600 volt rated wire except for the heater wiring for my builds. If  you want something else to worry about think about the voltage rating of resistors..The voltage rating on resistors is not the voltage drop across the resistor, it is the voltage that the resistor is carrying, same as the insulation rating of wire.

[Champ_49]

Thanks everyone for your input.  Looks like I will be using the wires supplied from Hoffman then.
Another thing I noticed..  I'm sure a lot of people here (pro's or not) have encountered the insulation melting or "stripping" off when soldering with PVC wire.
I had a local amp tech tell me that you have to have the iron really hot so quick in and quick out so the insulation has no time to melt.  I tried this and for the life of me I can never get the wire insulation to NOT fray off wire.  How do you guys do it? 

Maybe I'm just so bad with PVC insulation soldering but I can never get it right.  I do have some High temp PVC wire from tube depot where the insulation does melt but it tends to just melt inwards into the wire (instead of off the wire) which is a good thing for me.  Other cheaper wires I have tried (from the local electronic hobby store) I notice the insulation strips right off the end when the wire is heated exposing a lot of lead which i DON'T like.   So I have been using that wire from tube depot the whole time with good results.

My question is for leads coming off of the transformer wires, the wires almost always tend to strip off when trying to solder.  So i go the length of getting some heat shrink on the end of the wire so that the insulation doesn't come off and that way I can get the leads tight up against whatever I am soldering to.

How do you all do this?  I have seen a lot of PVC wires on builds where it seems like they were quick enough where the insulation doesn't strip with the heat.

Any ideas???

[Willabe]

I had a local amp tech tell me that you have to have the iron really hot so quick in and quick out so the insulation has no time to melt.

   

Try pre 'tinning' (just the least amount of solder you can) the striped end of the wire and the eyelet/turret/switch contact/etc. 1st.

This helps the solder connection get 'wet' quickly and suck up the solder. Also it helps to use a little solder flux paste, brush a little on both parts to be soldered, just a little, then 'tin' the parts. It helps clean the parts of any oxidation when heated, so it sucks up the solder.

I know you asked about transformer fly leads but, for other connections you can use Teflon isolated hook up wire, works great. Doug sells it in different colors.

Or, cloth push back hook up wire, (there's other 'cloth' covered wire out there that is PVC insulated wire that has a cloth braid over the PVC for looks. Some guys here use it and like. I would think that the cloth braid would help hold the PVC in place when heating it up?) Doug sells the 'push back' in different colors, another very good option.

My question is for leads coming off of the transformer wires, the wires almost always tend to strip off when trying to solder.  So i go the length of getting some heat shrink on the end of the wire so that the insulation doesn't come off and that way I can get the leads tight up against whatever I am soldering to.

I've tried that and it works pretty good. 

One thing I've noticed is that if the PVC wire I'm soldering is bent (in a rounded hook shape) at the very end instead of being perfectly straight, the PVC comes off real quick! (Even with pre-tinning.) As it heats up the PVC moves/pulls away from the wire itself, the PVC is trying to straighten itself out.        

It takes practice (I'm still getting better), you'll get it, hang in there.

                                       "You have to break some eggs to make an omelet."


                    Brad        

[Champ_49]

Thanks Brad.

I have used teflon mostly for my other JCM800 build.  Only for the leads coming off the board.  All other wire like the heater wire I used PVC.  Teflon is a pain in the ass for heater wiring. I tired that once and it was so slippery I gave up.     But other then that I use the teflon.  Only issue I had with that was that you had to strip it really well or have a special stripping tool for that.  I used this tool that has the guage slots and you measure approximately where you want to cut and one part of the tool grips the other end and the other strips the wire.  Sorry I forgot the exact name of the tool.  But even with that I found that it was hard to strip the insulation.  Sometimes not all the insulation would come off.
Using a regular wire stripper would tend to nick the wire.  I guess both have their advantages and disadvantage.  Or sometimes instead of pulling the regular wire stripper to pull the insulation off I will nick the insulation first and then pull it very slowly off with my fingers. 

I will try what you mentioned about the solder first to the contacts.  That would definitely get the solder to flow better onto the joint. 

I have come to realize that amp building or building anything for that matter is not just a matter of connecting wires but there is so much more to that.
The thing with transformer wires is I don't want to risk the insulation from coming off as I already cut it to length and if something were to melt off I would have very little to work with.   Of course you can leave some slack.. But for tranny leads I will stick to the heat shrink.  Always worked for me.   

[Ken Moon]

I use Clauss AW20 "bullet head"anti-wicking tweezers for tinning 20AWG stranded teflon wire (my favorite wire). They keep the solder about 1/16"away from the wire insulation, allowing the wire to bend easily at the end. Expensive but worth it.



How-to video:

https://www.youtube.com/watch?v=xpiyB7ZM3vg

[Champ_49]

Thanks Ken.  That was an interesting video.
I think I learned something there. So you shouldn't get the solder to wick under the insulation  when tinning?  Maybe that's why my pvc wires melt so fast?  I have been tinning the wires right to the edge of where the insulation Is and I'm sure some of the solder will get under the insulation. 

is this how all of you do this? Do you tin right to the edge or avoid the solder from wicking under the insulation.

[Champ_49]

Another real issue I have is wiring the heater wires especially. it's really hard to get it neat and straight like I've seen on a lot of builds by pros.  Although I'm not a pro I'd like to be able to wire heaters well.
One issue I have is getting the wires through the pins on the tube sockets. Especially on the preamp tubes. The last build I had a heck of a time trying to get two 18awg wires into pins 4-5. After tinning the wires get thicker as well. I've seen some people bend pins 4,5 towards each other. Is this a good idea? How do you guys do it? I was always afraid bending it like this would or could break the pins. I've done it on my last build. It worked but there's gotta be a better way.

I was wondering what wire I should use from the last power tube leading to the next prramp tube.  Would 20 awg be ok? or is it good practice to use 18awg on amy heater wire connected to the pin of a power tube.
Sorry.  It is a bit of a confusing question.

Another thing I did was when crimping the wire on the 8 pin power tube I used a plier and ended up bending A pin. These pins are also very fragile.  I had a broken power tube socket laying around and tested it by bending the pin and it only took a couple of turns back and forth for it to snap off.  I found myself having to be extra careful when bending and crimping the wires to get a good mechanical connection.

Is it just me or does anyone here have some frustration when wiring the heaters.  My heart races every time when I have to wire the heaters lol.

[John]

Everything gets easier with practice.


When tinning stranded wire, put a little flux on it (helps to clean and heat faster), hold your iron at the tip. When the flux smokes touch your solder to the wire, also near the tip, and wait till it soaks in a little bit. That's enough. You don't need to tin the entire way back to the insulation. (IMO anyway) You're just trying to make a nice solid tip for poking through holes.


Make the hook on the end of the wire before poking through the pin. That way most of the force is on the wire itself when you crimp it.


I use 20 gage solid on the heaters.... now, I'm usually only wiring 1 power tube so keep that in mind. If you're wiring a quad of EL somethings, probably 18 is a much better safety margin. OTOH, look at the traces on a PCB that include the heaters... what gauge are they? But from the power tubes to the preamp, you can use thinner wire since the preamp tubes draw much lower heater current. I personally don't worry about solid core for heaters because those wires get moved way less than any other wire in the amp from start to finish.


When working on my layout, I consider where the heater wires go first. I rotate the sockets so the heaters naturally run against the corner of the chassis. I don't like the heaters in the air, but that's just my personal preference. Everyone does things differently, and mostly, each person's way of doing things works.


Oh, one more thing. Get a little tin of flux, Radio Shack sells it, and use it on your connections. You'll find you have to let your iron on the joint for a much shorter time, and it makes better cleaner joints. IMHO. A little will probably last your lifetime.

[sluckey]

I use 20 or 22 gauge wire for nine pin tubes. 18AWG is way overkill and difficult for even the pros. That's why the pros don't use 18AWG. Heck, Hammond used 22AWG solid on most of their tube amps, even for big tubes.

My method for tinning stripped wire ends is... Stick the end of the wire into a container of rosin paste flux. Wipe the tip of my iron on a wet sponge and then touch the solder to the iron tip (called wetting the tip). You don't need a big ball on the tip! Now touch the iron tip to the end of the wire. The solder will 'wick up the length of wire. I'm not concerned with solder wicking under the insulation. I haven't used those anti-wicking tools since working in the USAF repair depot. I exclusively use PTFE (Teflon) insulated stranded wire. More expensive and harder to work with but well worth the expense and effort. There is no issue of melted insulation when using Teflon coated wire.

[Champ_49]

Thanks again Sluckey.
Yes I like to use teflon too. Works really well and you can get the connection right up against the insulation. i built the last amp using teflon. But I had a lot of trouble stripping it. The insulation is realky thin.  How or what tools did you use for stripping. I tried using many variety of wire strippers and ended up using the klein tools katapult stripper.http://ecx.images-amazon.com/images/I/81RoDmzzZRL._SX522_.jpg

But sometimes I noticed the insulation would somewhat shear and only half of the insulation would come off.  But that's not that big an issue since I can carefully cut the other half off.

Otherwise I tried a regular wire stripper for really short wires as the katapult won't be able to grab. So I just nicked the wire a bit and pulled the insulation off with my fingers since whenever I've tried pulling it off with the stripper it nicked the wIre.


so Sluckey,  do you even use teflon for the heater wiring? I tried that once but gave up.  The insulation was waaay to slippery  but I used it for other interconnects.

[shooter]

hold your iron at the tip

   

[sluckey]

I use Teflon for EVERYTHING, even shielded cable. (RG-316)

     http://home.comcast.net/~seluckey/amps/lil_maggie/m-04.jpg

Those strippers are fine unless you are working short pieces or in tight corners. I use a simple red handled Klein stripper available at Lowes. Sharp is the secret to stripping Teflon. Forget about even trying those "V" notch type strippers!

[Champ_49]

That looks really good! Wow!

Check this out.http://www.partsconnexion.com/MUNDORF-70803.html.

Over $17 a foot!

[Willabe]

I use a simple red handled Klein stripper available at Lowes.

I use the same red handled Klein stripper. They work great. With the Teflon I cut the insulation, then I slide it off the wire with my fingers. It seems to work easier that way. 

Sharp is the secret to stripping Teflon.

I bought a pair that I use ONLY for my amp builds, not for anything else.

I have a pair of the katapult strippers but with the teflon they do leave a little bit of the insulation. They work better for me on PVC covered wire.


                    Brad     

[Willabe]

Your link doesn't work.

[Champ_49]

Thanks.  Here is the link.http://www.kleintools.com/sites/all/product_assets/catalog_imagery/klein/11063w.jpg

Has anyone tried tefzel wire here??

[eleventeen]

"One issue I have is getting the wires through the pins on the tube sockets. Especially on the preamp tubes. The last build I had a heck of a
time trying to get two 18awg wires into pins 4-5."


On 9 pin sockets, 18 awg is about 95% impossible, and the struggling you'll have to do to make it work practically guarantees it will not be neat. It's just too darn big for the job. And that's too bad, because I have reels and reels of high end Belden 18 awg in all kinds of colors from long ago and far away. Yes, it is very good for speaker wires and for B+ wiring, but I have probably used 50 feet out of 5000 that I got for free. Sigh.


This is largely a matter of practice and heat control. It also helps to handle (with your fingers) the exposed conductor of wire as little as possible. The small bottle of flux will definitely make life a little easier.

[Champ_49]

Yup. I had to do some serious struggling to get those 18awg into the 9 pins.  Actually I had to squish the wire to get it thin enough to get through.  Other times it just went through.  But it was definitely a struggle.

I am going to get some flux.  Now I see there is flux paste and liquid flux (no clean).  Not sure what no clean means, I'm guessing there is no need to clean it afterwards?? 
Which would you guys recommend?  Paste or liquid?  I think Sluckey mentioned I use the paste?  But to dip the wire into it?

Thanks again

[eleventeen]

They are essentially the same thing. The paste will melt into the liquid that the liquid already is, well under the melting point of solder, once you apply some heat to it. The paste is preferable when you are WIRING something wire-by-wire because you can dip the lead/wire into the container of paste one-handed, whereas with the liquid tends to require two hands, which means putting down your soldering iron. But, if you have say a whole board full of components bolted into the amp chassis and now you are going to solder wires to the posts (if you do things in that order) then it's easier to brush all the lugs with the liquid and a little brush all at once. I might prefer the liquid, as you can pour out half a teaspoon into some kind of little container and dip your leads/wires into same. Of course I would tip it over about 6 times per amp build.

[Champ_49]

Thanks eleventeen. Maybe I will get both. 

[eleventeen]

You can get only the liquid but you need a "dipping dish" that is heavy as heck so it won't tip over because if you think about it, you are going to flick the thing over dipping leads into it. Bottle cap glued to a chunk of iron? That wouldn't be the worst idea in the world, because it would control (better) how deep into the flux you dipped whatever versus a 5/8" deep flux tin. Maybe you can find a chunk of thick iron and drill a 3/8" blind hole in it.


Soldering flux: Yet another item that used to cost 65 cents that's probably $10 for a teeny bottle.

[Champ_49]

Thanks eleventeen.   

Not sure what you mean.  Can't I just dip the lead into the flux?
I did see flux paste ay the local electroincs store.

[Willabe]

I use 20 or 22 gauge wire for nine pin tubes.

Small tubes like 12 _ _ 7 (12AX7, 12AT7, 12AY7, 12AU7), 5751, etc, only draw 300mA's of heater current. (Some small 9 pin tubes draw a little more.) 

A book I have list's 22awg as 2.4A and 20awg as 3.7A. (.300mA x 8 = 2.4A.)

So you can wire up 8  @  12 _ _ 7 preamp tubes with 22awg. No need for 18awg for the small bottle preamp tubes.


                    Brad       

[Champ_49]

Thanks Brad.

Yes it is great to know since trying to fit even a 20awg through the pins can be tricky. 
Especially when trying to put it through two pins (4 and 5 for the jcm800)