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Old 14th Sep 2018, 2:13 pm   #4
Boater Sam
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Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
Default Re: Failed 1951 radio, progressive. Bush DAC11.

Thanks.
I think we have all had enough threads as you describe despite me and others saying "get it working first" several times.

I replaced the decoupling caps because I was trying to get the HT as high as possible. They were pulling it down somewhat.

Trevor (Murphyv310) over on the Golborne forum has suggested putting a voltage doubler before the rectifier which looks like a smart idea.
A series capacitor in the live with a reverse diode to the neutral connected to the existing rectifier anode. By selection of the cap value the HT could be jacked up to a reasonable figure.

I'm surprised that Bush had such a different HT in the two sets, AC11 and DAC11.
They could found a few more volts for the HT I'm sure. Possibly by removing the dial lamps from the HT circuit. A 25% drop seems a lot.

The basic chassis was designed so that either version could be produced with minimal changes to meet the current demand at the time. DC supplies were becoming less common rapidly in the early 50s.
Hence the common valve lineup and the big rectangular hole in the AC/DC chassis.
Sam.
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