Working on the ST-120 today. I started wondering since there are 2 6.3v heater windings does the phase matter between the windings, and even between the tubes? I am thinking that since the tubes are indirectly heated probably not, but it seems the hum could be additive or cancelling depending on how it is wired. Am I overthinking this?
2 posters
Does heater phase matter?
bobgroger- Posts : 18
Join date : 2021-02-12
Bob Latino- Admin
- Posts : 3274
Join date : 2008-11-26
Location : Massachusetts
bobgroger wrote:Working on the ST-120 today. I started wondering since there are 2 6.3v heater windings does the phase matter between the windings, and even between the tubes? I am thinking that since the tubes are indirectly heated probably not, but it seems the hum could be additive or cancelling depending on how it is wired. Am I overthinking this?
Bob,
On the octal output tube sockets pins 2 and 7 are the filament or heater pins. When the manual tells you to connect the two twisted wires to pins 2 and 7, it does not matter which wire is connected to pin 2 and which wire is connected to pin 7.
Note 1 - if there was a difference, then the assembly manual would mention the difference.
Note 2 - If the manual does not mention about twisting wires, then it is unnecessary to twist the wires.
Bob