What rating of switch for HT Switching

[johndandry]

I would really like to make the on/off switch a 3 position and have the two HT on either side and in the middle, the amp is off. On-Off-On.

What switch do I want? thanks!!

[Leo_Gnardo]

Truth be told I haven't found any common toggle switch really rated to take 500V more or less from the HT supply. However, all the amps from way back up 'til now seem to have 250V 3A rated contacts, at least. Some rated 6A A quality manufacturer's switch tends to last decades without failure. Carling switches are mostly what I buy. Available thru Antique/CE Electronics in sunny Tempe AZ.

Some folks wire a hi voltage disc cap across the HV switch lugs. This is supposed to help prevent arcing and help the contacts last longer.

[Structo]

Yes, apparently toggle switches do not like DC.

With the two switch system, power and standby (B+), what I do is turn on the power, let it warm up a couple minutes then flip standby to play.

When I power down, I just flip the power switch off.
So I am eliminating half of the switching on the standby switch.

Not sure when arcing the switch contacts happens, when closing or opening contacts?

But after a while carbon will build up on the contacts, causing arcing to happen more easily.

Anybody have an old standby switch that they can take apart to check out the contacts?
Pictures please.

[Leo_Gnardo]

Not sure when arcing the switch contacts happens, when closing or opening contacts?

both. Keep in mind that 8000V per inch breakdown spec. And that's in dry air at sea level pressure. As one piece of metal is brought near the other, the current can jump in an arc and there you go...

But after a while carbon will build up on the contacts, causing arcing to happen more easily.

Heck, pieces of metal get vaporized, go missing, what may look like carbon is likely metal oxide settling nearby.

Funny enough the Carling 3A SPST switches used for standby and power in old Fenders seem to last 40-50 years with failures a rarity.

[David Root]

The big Carling 3-way switch is pretty bulletproof. Off, AC On (Standby), HT On (Play). I have used it, and the Fender style Carling switches too.

I used to use the Fender style long toggle for the AC and the short for HT, when they are on the back of the chassis, so you can feel which is which, but lately I use the long toggle on both if the switches are on the front panel.

Never had a failure with any of them, even above 500VDC.

[tubeswell]

If its a multi-pole multi-toggle switch on the high tension winding then the 250VAC 10A ratio should be fine (because its VAC you're dealing with).