While I've built many 9VDC solid-state projects (think effects for guitar players), I'm starting to test the waters on making some tube-driven devices. I was looking over some old schematics and kept seeing a reference to an "HT" attached to the plates of the tubes (usually ECC83s or similar) in the schems. I know it's a transformer reference, but what, exactly, does the "HT" mean?

Thanks,
IZA

 

Originally posted by ianderso@Apr 26 2006, 11:14 AM
While I've built many 9VDC solid-state projects (think effects for guitar players), I'm starting to test the waters on making some tube-driven devices. I was looking over some old schematics and kept seeing a reference to an "HT" attached to the plates of the tubes (usually ECC83s or similar) in the schems. I know it's a transformer reference, but what, exactly, does the "HT" mean?

Thanks,
IZA

[post=16562]Quoted post[/post]​

I think it might mean "High Tension". This arcane terminology still shows up in high voltage circuits. It generally takes a step-up transformer to go from 120VAC to a typical +300VDC plate supply.

 

Originally posted by Papabravo@Apr 27 2006, 02:32 AM
I think it might mean "High Tension". This arcane terminology still shows up in high voltage circuits. It generally takes a step-up transformer to go from 120VAC to a typical +300VDC plate supply.

[post=16564]Quoted post[/post]​

You are correct. HT means High Tension and EHT is Extra High Tension. EHT transformers are generally in the KV range.

HT transformers can have an O/P anywhere from about 100V to about 1KV. Some are multi tapped to provide voltages for the screen grid and supressor grid as well as the plate supply.