Single quantity custom made transformers in the EU? - Page 1
Forum section: electronics / projects

author: Uky
author_rank: Regular Contributor
timestamp: September 05, 2024, 11:49:12 am
content: Greetings forum.Considering repairing an old TWT amplifier with a burned HV transformer, I am looking fora supplier within the European Union that would be willing to make one single transformer custom wound.The voltages involved are ~ 640VAC (less than 50mA), 1350V AC (about 150mA)and a primary voltage of nominally 230V, 50Hz with taps +/- 5 and 10%Total power less than 200VA.Have anyone here been able to find a supplier willing to manufacture such a transformer?

author: Kryptychon
author_rank: Contributor
timestamp: September 05, 2024, 04:11:36 pm
content: Hi Uky,have a look here:https://www.walcher.com/en/pk/transformers/They have a business unit specialised in custom made transformers, even single quantity.Never had the need for one, but I already got transformer accessories (soft start relays and such) from them.Best regardsApe

author: TimFox
author_rank: Super Contributor
timestamp: September 05, 2024, 04:27:35 pm
content: I have not tried them, but the French audiophile company Audiophonics offers custom-wound toroidal power transformers:https://www.audiophonics.fr/en/toroidal-transformers/custom-toroidal-transformer-all-power-p-3675.html

author: armandine2
author_rank: Frequent Contributor
timestamp: September 05, 2024, 05:44:58 pm
content: not tried a custom one , but this UK company were ok - competitive price and 2-week deliveryhttps://airlinktransformers.com/about-airlink-transformers

author: branadic
author_rank: Super Contributor
timestamp: September 05, 2024, 06:17:10 pm
content: I have good experience withhttps://www.wickeltechnik-langer.de/,you can read about it in the metrology section, they made the HV transformer for a Valhalla2720GS and a Fluke 730A for me.-branadic-

author: floobydust
author_rank: Super Contributor
timestamp: September 05, 2024, 06:19:03 pm
content: Sowter Transformers UKQuality is high, prices are high- moreso since the business changed hands.Lundahl Transformersproduct for audio- tiny little cores, sound not great compared to others. Did not like. They've gone heavy on audiophile marketing, but are located in Sweden and might be worth hitting them up.

author: danieljfarrell
author_rank: Contributor
timestamp: September 05, 2024, 06:24:35 pm
content: +1 from Airlink. Mike knows his stuff and has custom made transformers for me.

author: Uky
author_rank: Regular Contributor
timestamp: September 05, 2024, 07:00:05 pm
content: Thanks for all suggestions.Vielen Dank für alle Vorschläge.A transformer such as the one I am looking to buy will most likelybe wound on an E- or C-core. Toroidial transformers for these voltagesare difficult to wind because of the kV insulation requirements.I have wound a high voltage transformer myself, having repaired a Tektronix 576 Transistorcurve tracer CRT circuitry using the original ferrite core with a new "printed" bobbin. Winding kV means havingto apply a special winding tchnique with plenty of interlayer insulation and always startthe next layer from the same side as the previous one. (That transformer required > 1000 turns0.1mm Cu wire). It was a PITA but the process was successful.

author: edpalmer42
author_rank: Super Contributor
timestamp: September 05, 2024, 07:39:40 pm
content: Have you considered using two transformers?It wouldn't be as elegant a solution, but it would be more available and possible less expensive.

author: TimFox
author_rank: Super Contributor
timestamp: September 05, 2024, 09:54:42 pm
content: Again, I haven't tried them but Audiophonics claims "4 kV flash test" and they do cater to the vacuum-tube audio market.

author: coppice
author_rank: Super Contributor
timestamp: September 05, 2024, 09:59:15 pm
content: I haven't worked with a TWT that ran on such a low voltage. Is there a multiplier after the transformer?

author: coppice
author_rank: Super Contributor
timestamp: September 05, 2024, 10:02:40 pm
content: Quote from: TimFox on September 05, 2024, 09:54:42 pm4kV flash testing is the normal minimum test for a mains transformer.

author: Uky
author_rank: Regular Contributor
timestamp: September 06, 2024, 11:28:17 am
content: The TWT is Varian VTH 6079H1.It's frequency range is 4-10GHz but according to my sources, this tube does performat 10.368.I made a small calculation error: The DC voltages necessary isCathode to Helix (at GND potential): 2800V ~ 1.5mACathode to Collector: 1900V ~ 56mAThere are several different configurations according to Varian but the one aboveis supposed to be the "Standard" configuration.The windings will obviously have to be made using thicker wiresbut the total VA rating of the transformer will be in the order of 250...300VAin order to cope with rectifier peak currents.They need to be able to be elevated in respect to GND which requiresa certain amount of insulation.The 6.3V filament will be supplied by a home made transformer usinghigh voltage PTFE wiring.

author: ftg
author_rank: Frequent Contributor
timestamp: September 09, 2024, 07:28:21 am
content: I know some folks who have bought custom wound transformers for tube linears from Trafox / Muuntosähkö Oy in the past.They might still do one-off's.https://www.trafox.fi/en/