Chinese Transformers - UK Vintage Radio Repair and Restoration Discussion Forum

Petedox · 10th May 2021, 12:24 pm

Has anyone had any experience of these? I'm thinking mainly of valve output TX's.

Ed_Dinning · 10th May 2021, 1:00 pm

Unfortunately yes
I had one for repair from a high priced hi-fi amp. Core appeared to be Stalloy and was thicker than the usual 0.35mm. More important was that the interlayer insulation appeared to be from a newspaper
Moisture had been absorbed and it had gone down Pri/ Sec; this had then taken out the mains transformer and LF choke.

There may well be good quality ones available, but not from this particular supplier

Ed

joebog1 · 10th May 2021, 11:12 pm

As Ed says!! you can get some OK ones. I have unwound one to see how well it was made. KNOTTING the two ends of the primary together to hold the ends in place!!!! With 240 volts across the varnish which I suspect was polyurethane. Insulation between primary and secondary was yellow mylar tape which I use myself, but NOT for primary isolation. It was four sections, pri then sec then primary then secondary.

NOT Hifi!!!

Joe

Diabolical Artificer · 11th May 2021, 7:05 am

With regards to OPT's you get what you pay for and like anything buying from unknown manufacturers can be problematic. Unless an OPT manufacturer gives full specs like L, leakage L, laminations, insulating material etc I'd be wary.

If price is an issue VVT and Primary Windings here in the UK make decent OPT's at reasonable prices, though there is a long lead time at present at PW and I wouldn't be suprised if other winders are the same. There are several other such suppliers in the UK.

If you buy from the old eastern block countries you can get an excellent deal,check Toroidy in Poland for instance, there's also a couple of blokes on DIYaudio who wind decent OPT's for a good price,the kicker is shipping.

Lastly Edcor and Hammond won't bankrupt you,buy from Mouser or Digikey and shipping is free for orders over £30, not sure if there's a surcharge for heavy items. Again expect long lead times due to CV19.

Andy.

Petedox · 11th May 2021, 11:41 am

Thanks for info, I've bought from Hammond and Majestic in the past and these comments are very interesting.

I have found that generally there has been quite an improvement in Chinese electronic parts (from both a hobbyist and industrial perspective) over that last decade or so. Maybe I just need to wait a bit longer!

10th May 2021, 12:24 pm	#1
Petedox Pentode Join Date: Feb 2020 Location: Waterlooville, Hampshire, UK. Posts: 200	Chinese Transformers Has anyone had any experience of these? I'm thinking mainly of valve output TX's. __________________ Pete BVWS Member

10th May 2021, 1:00 pm	#2
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Chinese Transformers Unfortunately yes I had one for repair from a high priced hi-fi amp. Core appeared to be Stalloy and was thicker than the usual 0.35mm. More important was that the interlayer insulation appeared to be from a newspaper Moisture had been absorbed and it had gone down Pri/ Sec; this had then taken out the mains transformer and LF choke. There may well be good quality ones available, but not from this particular supplier Ed

10th May 2021, 11:12 pm	#3
joebog1 Banned Join Date: Jun 2015 Location: Mareeba, North Queensland, Australia Posts: 2,704	Re: Chinese Transformers As Ed says!! you can get some OK ones. I have unwound one to see how well it was made. KNOTTING the two ends of the primary together to hold the ends in place!!!! With 240 volts across the varnish which I suspect was polyurethane. Insulation between primary and secondary was yellow mylar tape which I use myself, but NOT for primary isolation. It was four sections, pri then sec then primary then secondary. NOT Hifi!!! Joe

11th May 2021, 7:05 am	#4
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,657	Re: Chinese Transformers With regards to OPT's you get what you pay for and like anything buying from unknown manufacturers can be problematic. Unless an OPT manufacturer gives full specs like L, leakage L, laminations, insulating material etc I'd be wary. If price is an issue VVT and Primary Windings here in the UK make decent OPT's at reasonable prices, though there is a long lead time at present at PW and I wouldn't be suprised if other winders are the same. There are several other such suppliers in the UK. If you buy from the old eastern block countries you can get an excellent deal,check Toroidy in Poland for instance, there's also a couple of blokes on DIYaudio who wind decent OPT's for a good price,the kicker is shipping. Lastly Edcor and Hammond won't bankrupt you,buy from Mouser or Digikey and shipping is free for orders over £30, not sure if there's a surcharge for heavy items. Again expect long lead times due to CV19. Andy. __________________ Curiosity hasn't killed this cat...so far.

11th May 2021, 11:41 am	#5
Petedox Pentode Join Date: Feb 2020 Location: Waterlooville, Hampshire, UK. Posts: 200	Re: Chinese Transformers Thanks for info, I've bought from Hammond and Majestic in the past and these comments are very interesting. I have found that generally there has been quite an improvement in Chinese electronic parts (from both a hobbyist and industrial perspective) over that last decade or so. Maybe I just need to wait a bit longer! __________________ Pete BVWS Member