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 Post subject: Re: testing audio tubes for microphonics
PostPosted: May Thu 02, 2019 3:05 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 4222
Location: Sunbury, Ohio 43074
Quite interesting website Martin. Almost makes me want to learn German, but I fear my patience these days isn't what it used to be. For now I'll just look at the pictures :)

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 Post subject: Re: testing audio tubes for microphonics
PostPosted: May Fri 03, 2019 8:05 am 
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Joined: Nov Wed 15, 2006 7:56 am
Posts: 1322
Location: germany
I have designed and build that in the old style, using solding stripes and wires binding.
As a experience. The plan what is where is the one and all, with the shortest possible connection. ( see Heathkit plans) The microphonic sensitive parts are the both microphone preamps, each with a EF86. The layout have a centered grounding at one point (negative out from PSU.). The most time is required for planing, the building is rather fast about the good plan.
Martin


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 Post subject: Re: testing audio tubes for microphonics
PostPosted: May Fri 03, 2019 9:41 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11304
Location: Powell River BC Canada
What I used to do with German tape recorders like the Uher Stereo Record 3
was to add a new bridge rectifier fed from the transformer winding the for the magnets
needed to operate the record/play relays and the capstan seal-in.

That gave me 12 volts DC, to power the heaters of the EF86 tubes, and made a hum free
machine.

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: testing audio tubes for microphonics
PostPosted: May Fri 03, 2019 2:25 pm 
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Joined: Mar Sun 31, 2019 3:44 am
Posts: 95
Location: Alberta,Canada
this morning i went back and looked all the pictures. very nice work Martin.
in 1979 i bought 2 sets of Canton speakers 1 pair of CT2000's and 1 pair of CT1000's 1 woofer in each is done and parts here are near impossible to find , but i am not giving up .
Cheers Don


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