SE 813 OPT..Am I On the right Track? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th June 2005, 06:16 PM   #1
diyAudio Member
 
valveitude's Avatar
 
Join Date: Apr 2005
Location: Naches,WA
Default SE 813 OPT..Am I On the right Track?

First off, thank you Yvesm!! Your OPT Design Assistant program is great. I, like a lot of people, was starting to pull my hair out wading through all the differing design approaches published on the web and elsewhere. Being able to see all the parameters change with subtle changes of the design without blistering your calculator finger is fantastic. There are two other freeware programs that make up my opt software kit, and I recommend them highly. First is Wiretrons wire program available here:

http://www.wiretron.com/free.html

It has a ton of useful wire info and conversion utility. The other is Josh Madison’s Convert program, available here (get the zipped version):

http://www.joshmadison.com/software/...t/download.asp

Its invaluable for converting back and forth from different measuring systems.

I was given an industrial 3-phase motor controller to harvest parts, in this goldmine were 2 chokes with this core…

Click the image to open in full size.

I have no way of knowing if they are m6 or not, but they do appear to be grain oriented. The laminations are .025” (.6mm), and as a bonus, were assembled with an air-gap, so the lams are already set up for an SE opt.

Here is a screenshot of what I think is the best design compromise…

Click the image to open in full size.

Not knowing if it is m6, I am assuming it isn’t, and, took a conservative approach with the Bmax. I read somewhere that a lower Bmax also minimizes the effect of thicker laminations. Is this correct? It seems to make sense.
One of the things I really appreciate with the program is the “Actual Primary Z” window. I was having a hard time trying to fit the windings with a target of a 5k primary, when I realized that lowering the target actually got me closer to what I wanted (5k-6.5k).
The Fo is a lower than I like, but I plan on winding in 2 sections per Radiotron. This will lower the stray capacitance by a factor of 4.

This is my planned winding scheme…

Click the image to open in full size.

Because of the 800-1200 volt B+, I am going to pot the transformer. I plan to use wax, either beeswax or paraffin. Anybody have any recommendations as to which is the better choice, or could suggest something else?

If anybody sees anything I’ve overlooked, or could do better, please let me know. I’ve attached the project file (mox) if anybody wants to have a go. The core data is in the above screenshot

Thanx,
Casey
Attached Files
File Type: zip opt.zip (426 Bytes, 43 views)
__________________
Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
  Reply With Quote
Old 10th June 2005, 02:56 PM   #2
jlsem is offline jlsem  United States
diyAudio Member
 
jlsem's Avatar
 
Join Date: Jun 2003
Location: Dallas,TX
Quote:
I have no way of knowing if they are m6 or not, but they do appear to be grain oriented. The laminations are .025” (.6mm), and as a bonus, were assembled with an air-gap, so the lams are already set up for an SE opt.
If they are grain-oriented it should be a fine output transformer. M6 laminations would be thinner but if you Z-wind the bobbin, high-frequency response should be good.

Quote:
Because of the 800-1200 volt B+, I am going to pot the transformer. I plan to use wax, either beeswax or paraffin. Anybody have any recommendations as to which is the better choice, or could suggest something else?
Microcrystalline wax is the usual and much less expensive than beeswax. It's available here:

http://www.freemansupply.com/MicroCrystallineWa.htm

John
  Reply With Quote
Old 10th June 2005, 04:21 PM   #3
diyAudio Member
 
valveitude's Avatar
 
Join Date: Apr 2005
Location: Naches,WA
Quote:
M6 laminations would be thinner but if you Z-wind the bobbin, high-frequency response should be good.
Thanx for the reply John. I'm not clear on the term "Z-wind", looking at my winding diagram above, the primary does resemble a sideways "Z". Is this what you mean?

Quote:
Microcrystalline wax is the usual and much less expensive than beeswax
Thanx for the tip. I'll check the price and see how it compares to beeswax around here. There are a lot of bee farms around hear (Eastern Washington) and I'm going to see what the bee combs cost getting them direct from the source.

Casey
__________________
Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
  Reply With Quote
Old 10th June 2005, 05:04 PM   #4
diyAudio Member
 
Join Date: Dec 2001
Location: Earth
Hi
The laminations looks like a very bad transformer size. 0.6mm i think it is even bigger than normal power trans grade of m19 at 0.5mm only.
I suggest for your 813 you further reduce your bmax to preven core saturation.

Pot helps but beeswax is better but at a very much increase in cost. Paraffin is much cheaper. Also beeswax is often used to prevent corona discharge at that voltage. I suspect even parafin help too. ANother wax to look into is microcrystalline wax. No bad good too. Bartolucci uses them too.
  Reply With Quote
Old 12th June 2005, 03:33 PM   #5
Yvesm is offline Yvesm  France
diyAudio Member
 
Yvesm's Avatar
 
Join Date: Jul 2004
Location: Ardeche
Default On Tracks !

Hi Valveitude !

First, apologies for delay (was off home) and thanks for apreciation !

Quote:
I have no way of knowing if they are m6 or not, but they do appear to be grain oriented. The laminations are .025” (.6mm), and as a bonus, were assembled with an air-gap, so the lams are already set up for an SE opt.
No, there are certainly not M6x (too thick) but, in an SE design, the permeability is already killed by the gap, and the only remaining limitation is the Bmax.
Lo grade iron saturates at lower B, but less abruptly than M6x, and you set lowest freq at 20 !!

Quote:
Here is a screenshot of what I think is the best design compromise…
Looks fine, just why do you use 8 Ohms in the "reflected load" when you set the secondary at 6 ?

Also check at what happens if you set the tube Rp at some 5000 ohms (unless you use the 813 triode strapped ?)

I beleive that with such size of tranny, the "dual bobin" arrangement is the best to lower the parasitic cap, even if there is room left to increase insulation thickness (or have access to some TEFLON foils).

Sorry for not having (yet) introduced this option in the program !

Anyay, your on the tracks, for sure.

Yves.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Keep track of your papers? jan.didden Everything Else 16 4th October 2006 10:49 AM
This is really totally off track................ ashok Everything Else 1 30th May 2006 11:50 AM
am i on the right track?? dawgbite Subwoofers 9 26th April 2006 08:46 AM
is my new design on the right track? xdissent Solid State 2 25th November 2003 12:27 AM


New To Site? Need Help?

All times are GMT. The time now is 11:31 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2