Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders.

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Tube DIY Asylum ]

---

[ Alert Moderator ]

---

RE: UTC output transformers LS-63

Posted by mqracing (M) on April 16, 2015 at 12:09:45

In Reply to: RE: UTC output transformers LS-63 posted by dave slagle on April 16, 2015 at 10:07:30:

Dave wrote:

"Ultimately If I had the LS-63's I'd give it a shot but I don't think I would go on an ebay hunt to try it out."

this trans is just begging to be parafed. It would excel at least in terms of it's magnetic curcuit behaviour.

You'd have the full complement of the (as advertised) 275H not the diminished 15 or 20 henries after applying the dc (unbal) plate current
as per your graph.

From the vantage point of flux density... with the AC flux and dc flux added together I would guess that this unit is probably getting close to the "redline"...

now remove the dc flux component and we have 86.6 volts across the primary... we will have tons and tons of magnetic headroom... the core will be loafing....

I did a quickie sim (posted earlier) using VoltSec's parafeed caculator;

Rp 800 ohms
Rload 2500 ohms
pri DCR 125 ohms
pri L 250H
Cparafeed 5uf
L plate choke 40H
R plate choke 325 ohms

No output ringing/peaking

-3db large signal @ 5.8 hz

compare that to the -3db point of 26.5 hz using Tre's series fed example. The parafeed will go two plus octaves lower (for -3db point) than the series fed example.

And even if we're not in need of a low freq power response down to six or so hertz... the advantage is that one, two, three and so on octaves above the six hertz will benefit from lower stress and less work for the output tube... it's a win, win.

my only caveat is that push-pull transformers are designed (the better ones anyway) with the push and pull halves of the primary being mirror images of each other in terms of coil geometry...

if you use a PP trans single ended you "upset" the voltage and capacitive gradients that the trans was designed for...

designing a single ended output as a dedicated SE trans... your coil design and the variables of that process can be moreso optimized for this type of operation.

But I'd go parafeed in a heartbeat vis-a-vis using this PP trans in a conventional series fed circuit.

MSL

Builder of MagneQuest & Peerless transformers since 1989

Edits: 04/16/15 04/16/15 04/16/15 04/16/15 04/16/15

This post is made possible by the generous support of people like you and our sponsors:

Western Glow Tube Service

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---