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    ST-35 power supply query

    Captain Coconut

    Posts : 233
    Join date : 2009-10-13
    Age : 65
    Location : Great White North

    ST-35 power supply query

    Post by Captain Coconut on Fri Dec 06, 2013 10:28 am

    I have an original ST-35 with Gillespie's EFB mod which is a great piece of gear, but I was wondering about the rectifying diodes. They're the usual 1N4007 and I'm thinking about replacing these with the Cree SiC Schottky's. The 1N4007's are 1A 1000V rated as per the ST-35 manual, but the closest I can find from Parts Connexion are 5A 1200V. I guess the little extra power rating would be a good thing, except that some people claim that Schottky's don't like to be used in high voltage situations. Maybe theses people were talking about the older models.

    Anyhow, would these be applied in the same manner: one leg of the Schottky to the PT secondary and the other end to the first stage of the can cap? There appears to be a mounting tab for these which I'm guessing you don't want touching anything metal. So I guess having them suspended in air would be appropriate. Do these get very hot and would the small chassis be enough room for ventilation?

    Please advise. Thanks

    Posts : 1435
    Join date : 2008-11-30

    Re: ST-35 power supply query

    Post by tubes4hifi on Sat Dec 07, 2013 3:13 pm

    yes, they get VERY hot and they do need heat sinks and they need electrical isolation!
    They also tend to have a much higher voltage drop than regular diodes, about 2v each instead of 0.7v each
    use UF4007 as ultra-fast alternatives to the similar but slower 1N4007, and you can also put .01uF caps in parallel with them

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