PT high voltage secondary question

[lifer]

i've noticed differences between a couple layouts. i hope i can get an answer to this.

~one layout has the HVolt. secdary CT going to F4 positive lugs.

~another shows it going to F5's negative lug.

does it matter at all? thanks for any help--

[flemingmras]

i've noticed differences between a couple layouts. i hope i can get an answer to this.

~one layout has the HVolt. secdary CT going to F4 positive lugs.

~another shows it going to F5's negative lug.

does it matter at all? thanks for any help--

If by F4 and F5 you're referring to fuses, fuses are not polarized.

[lifer]

If by F4 and F5 you're referring to fuses, fuses are not polarized.[/quote]

no, "F"= filter cap

[flemingmras]

You're probably referring to the difference between a 50 watt and a 100 watt power supply.

The 50 watt power supply has a transformer that puts out double the needed voltage across the full winding and references the CT to ground, then has a rectifier (or two in series) on each outside HT winding that join together at the positive of the first filter cap with the standby switch between the rectifier and the first filter cap. They call this a full wave grounded center tap rectifier.

The 100 watt power supply has a transformer that puts out the needed voltage across the full winding and uses a bridge rectifier. The first two filter caps are wired in series and the CT connects to the series connection point of the two caps...usually connected to the positive of the bottom cap in the string. This allows each 1/2 of the HT secondary to charge up each cap independently, while the bridge rectifier is constantly switching which 1/2 of the HT secondary is charging which cap. This is done to ensure a voltage balance across both caps without having to use bleeder resistors. They call this a full wave bridge voltage doubler. Although it's not really a doubler at all unless you look at it from the angle that you're doubling the voltage of each 1/2 of the HT winding. But having the bridge rectifier across the full winding does this by default.

The second arrangement shares the exact same topology as a full wave grounded center tap dual polarity power supply, but instead of grounding the CT and series connection point of the two filter caps, they ground the negative output of the supply instead. This works because if you have a dual polarity power supply and you measure across the positive and negative outputs, the measurement will be DOUBLE what the positive supply and the negative supply voltage would be.

Yes it does matter because for both topologies, you use a different power transformer.

[lifer]

ok- cool- thanks flem