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In Reply to: Your UTC A-18 experiments: posted by drlowmu on January 30, 2004 at 19:31:52:
fingers get too cold to adjust the clip leads and I have to quit. Also firing up old 'lytics when they are that cold makes me nervous.
But I do have a heated basement with all kinds of test goodies. Signal gens, THD analysers, square, ramp, sine, scopes. And a big box of tranformers I did just the same tests with in the 90s.
But I'll tell you this now. There ain't no free lunch with this type of transformer. I gave up on the cheap\creative and custom built stuff and finally bought the Sowter. After about two years of playing with that I sold it and went back to 1940s and 50s "classic" phase splitters.
I've found that one of the best ways to get good phase splitting above 10Khz is to have a transformer that is wound on a split bobbin with one secondary reverse wound and a few interleaves. The two primaries are wired parallel so L gets wacked. Also the core should be as small as possible. This is no small feat, maybe there are two or three available in the world today. Even then when you take the amp to a friends house it sounds like shit because their preamp can't drive it nicely so you have to have a dedicated buffer or always use the preamp you designed the amp with.
I'm sure some other folks have better ideas but this is what several years and hundreds of dollars have taught me. YMMV
Hi Douglas ,
The answer is simple : lag the shed . I insulated my workshop with two layers of 1/2" polystyrene sheet then added a hardboard outer covering . A simple fan heater on a timer ensures the temperature never drops below zero , I have a max/min thermometer which confirms this . No 'deep freeze' treated valves either ;)
Five years ago I have "been there and done that" over one winter.
Boy, ya gotta be real motovated to work and concentrate in those conditions, .......sorta like the college-aged pianist practicing in the unheated flat .........in the movie "Shine" .
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