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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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27th Nov 2022, 2:41 pm | #21 |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,311
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Re: Output transformer HT connection.
A sort-of hybrid solution if you want to stick to a smaller valve rectifier is to generate the output valves' anode HT using solid-state rectification but everything else, including their screen grid HT, using a valve rectifier. The slow warm-up of the valve rectifier can protect the output valves' cathodes from a high electric field at switch-on via the screening action of the screen grids. The valves do need to be able to survive a large anode to screen voltage briefly though. And you do need two HT filters, of course.
Cheers, GJ
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27th Nov 2022, 3:59 pm | #22 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,658
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Re: Output transformer HT connection.
Thanks again all. I'll do some experiments at some point but the consensus seems to be connect the OPT CT after the choke.
Andy.
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27th Nov 2022, 10:08 pm | #23 |
Banned
Join Date: Jun 2015
Location: Mareeba, North Queensland, Australia
Posts: 2,704
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Re: Output transformer HT connection.
Using valve rectifiers today is a bit of a problem unless you already have decent ones available.
Modern rectifiers are not as reliable as the genuine article. I used buy up every valve rect that I could find providing it was NIB. VERY hard to find these days and for those that are out there, some are as expensive as a very good quality 50 watt output transformer. So, me, the audiophool purist has changed over to sand rectifiers. Fast recovery in large currents are cheap and plentiful. I still use capacitors across them though just to make sure. If you have "delicate " output valves a soft start and HT delay are very easy and cheap to organise. Just my two bobs worth. Joe |