Zener between PT CT and Gnd.

[petemoore]

To make this a simple 'T/F' question: For a Zener diode Vdrop trick to work, the cathode is connected to ground, the CT is connected to the anode to produce a lifted ground voltage at anode/CT ?
NTE5265A package says "Anode to Case" which has to = anode to ground [if following various reads which stress heat dissipation requires chassis bolt-down]. 25v / 50w zener...installed as such [note to self: after reading all the many directions, and planning it out...don't forget to look for and hopefully read the other directions when/if they ariive].
If bolting it down is backwards, this poses new mounting issues, perhaps I've ordered the wrong diode package ?

[petemoore]

Works fine with the cathode to ground.
Mica sheet and insulating 'washer' used to insulate it on a small heat sink, bolted to chassis, doesn't seem to get past 'warm', and dropped from 396vdc to 372vdc the B+ voltage, tubes seem to not be redplating at that point so it's looking pretty good.
No matter how complete the plan seems, it's always best to read the new directions when they come in..reminder to self.
Anyways is the "K" version is a better choice for this.

[DirtyGeorge]

Sorry Petemoore, you have the wrong part. The cathode needs to bolt to the chassis. To use your part you would need to mount it to a heat sink that is insulated from the chassis.

DG

[petemoore]

I used Ted's calculator [thanks Ted !] and it spit out 6w dissipation.
Fortunately that's not equating to 'massive' heat, and the 1/2 a cig pack sized heatsink is getting 'just warm', so I feel like I can sort of trust the insulating hardware which the zener package contained, a Mica washer, and a nylon 'insert washer'...
Maybe I'll call the supplier...I did ask for tech support and told of dropping B+ with a bolt down chassis, I know how parts shopping can be...we both missed the "K" suffix as being a 'priority specification' over 25v or 50w.