Would there be any harm using 10K OPT for 45 tubes?

[soulmerchant]

Hi Pieter

As an aside, I now see that this polish winder toroidy is claiming to be able to do single ended with air gap.

I guess they made some mistakes along the way, especially with the chokes, but they now claim to have new cores. Their chokes appear now to be more useful.

How hard do you think that is to do though? I mean.. in practical terms, it must be difficult to do different air gaps on torroidals. Its not often that you see someone offering torroidal OPT with air gap for single ended.

 

[pieter t]

My own experience with toroidals are the autoformer volume controls and MC step up transformers; on my toroidal winding machine the larger toroidal cores for output transformers don't fit apart from the fact that I prefer straight bobbins for interstage and output transformers. So I use c-cores for these.
When I am right toroidal cores are available in split halves so air gaps can be applied; just needs a band for assembly before starting the winding.

 

[LinuksGuru]

Air-gapped toroidal cores are very common, especially made in China with amorphous and nanocrystalline ribbons.
GOSS (grain-oriented steel cores) variants are more rare birds, but still in reasonable supply from specialized companies, like Lohse Ringbandkerne GmbH.

Few EU transformer manufacturers assemble air-gapped toroids in their own workshops.

 

[pieter t]

Simple split toroidal core:
www.waasner.de/fileadmin/Assets/PDFs/Katalog_Waasner_12_2015.pdf#page=48

 

[hpeter]

Dear 45

How many times have you been to Japan in the last 5 years? I go every year and will be going again this year. Local DIY is drying up there. I know from talking with dealers and locals.

Tamura staff is also mostly past retirement age. Hashimoto is still producing, yes. Noguchi is a niche business. The other producers I know as well, but they really only cater to the local market.

Here are the sad facts:

1. No new designs. Simply nothing new out of Japan in ages. Yes, they did much in the 1970's and 1980's but since then it has been a slow and steady decline much like the Japan economy as a whole.
2. They completely missed the parafeed movement.
3. In the last few years I am finding many foreign transformers in Japan. You name it, they have it. In the past you would never find new US transformers in Japan. The China and Taiwan stuff abounds as well. That was not the case 10 years ago.
4. I am seeing significant numbers USED Japan transformers in shops. Basically, amplifiers are getting stripped for parts. While I enjoy this development as I get the occasional bargain, it is on the whole not good.

I do love their single-ended output transformers. For the size they are truly impressive. You of course MUST be aware of their primary impedance.. but others have already discussed this. The interstages are actually most interesting for me, if you know what I mean.

But today, you can get similar NEW quality OPT's from sources in Asia, Europe and the US too. Also, many of these sources will build to spec and can even do design... That is not possible in Japan since design competency left long ago. These are my observations. Take it or leave it.

Hate it or like it, EI are more or done. Better stuff available on shops. PP toroids will kill any EI.

 

[disco]

Let's drop the big one...