Would any of you be so kind and give me the core dimensions and/or the dc resistance values of the original A-470 transformer?
I have the winding data but would need this additional data to be able to check if my attempt to calculate winding Rac/Rdc relation and proximity loss real/imaginare part is correct.
Complete data from ANY other OPT/amp combination would do as well.
Ideally, what i would need is the following:
Amp circuit diagram, specs, frequency response curve and measuring conditions
Core dimensions
Winding build up
Isolation build up
Primary and secundary turns per layer
Primary and secundary wire size
Primary DCR
Thank you for any assistance
Pete
I have the winding data but would need this additional data to be able to check if my attempt to calculate winding Rac/Rdc relation and proximity loss real/imaginare part is correct.
Complete data from ANY other OPT/amp combination would do as well.
Ideally, what i would need is the following:
Amp circuit diagram, specs, frequency response curve and measuring conditions
Core dimensions
Winding build up
Isolation build up
Primary and secundary turns per layer
Primary and secundary wire size
Primary DCR
Thank you for any assistance
Pete
Last edited:
Tom Bavis posted a dropbox pdf doc with a lot of measurements -
https://www.antiqueradios.com/forums/viewtopic.php?f=6&t=258816&view=next
https://www.antiqueradios.com/forums/viewtopic.php?f=6&t=258816&view=next
From Shannon's post here -
http://www.diytube.com/phpBB2/viewtopic.php?f=6&t=6417#p52359
http://www.diytube.com/phpBB2/viewtopic.php?f=6&t=4794
From my mid 70s Japanese Dynaco A470 (out of circuit, on my bench):
Measured with Wavetek Meterman 37XR:
Center Tap to front plate lead = 87 ohms
Center Tap to rear plate lead = 104 ohms
Center Tap to front screen lead = 29 ohms
Center Tap to rear screen lead = 34 ohms
I measure 10H from center tap to either plate connection at 200Hz.
Shannon
Thanks to Gregg Van Der Sluys (geek) and Michael S. LaFevre Of MagneQuest (mqracing) for the information
at this link below
http://www.diytube.com/phpBB2/viewtopic.php?f=6&t=3694
The core size for the A-470 is an EI-112 and the stack height is 1.875".
Standard holes. The grade of lamination is 29 gauge M6.
Core Dimensions
A470 Windup details
A470 Windup schematic
David Hafler's patents also seem to have a lot of information on the winding
techniques ( I glanced at one of them - it was quite dense reading) -
https://patents.google.com/patent/US2710312A/en
https://patents.google.com/patent/US2815408A/en
David Hafler's interview in the Vacuum Tube Valley magazine (issues 14, 15) -
https://web.archive.org/web/20181126083637/https://hafler.com/pdf/interview-with-hafler-pt1.pdf
https://web.archive.org/web/20190303161742/http://www.hafler.com/pdf/interview-with-hafler-pt2.pdf
David Hafler (seems to he may be referring to the A430, but he also says others like A470 are similar) -
The Dynaco design had something that was very rarely done, I had not seen any-body do it in output transformers. It inverted part of the winding. The coil was spun in the opposite direction and windings were put in parallel, criss-crossed sections. It is a little hard to describe. It was interweaved through a parallel connection rather than series connection which I had not seen other transformers use.
So the transformer had four winding sections. The first and third were wound in opposite phase and inserted backwards in order to make it work out. The secondary came in between the first and third or second or fourth sections. This is hard to describe without drawing a diagram. You could probably find that patent very easily if you wanted to look it up. It shows that both series had parallel arrangements.
http://www.diytube.com/phpBB2/viewtopic.php?f=6&t=6417#p52359
http://www.diytube.com/phpBB2/viewtopic.php?f=6&t=4794
From my mid 70s Japanese Dynaco A470 (out of circuit, on my bench):
Measured with Wavetek Meterman 37XR:
Center Tap to front plate lead = 87 ohms
Center Tap to rear plate lead = 104 ohms
Center Tap to front screen lead = 29 ohms
Center Tap to rear screen lead = 34 ohms
I measure 10H from center tap to either plate connection at 200Hz.
Shannon
Thanks to Gregg Van Der Sluys (geek) and Michael S. LaFevre Of MagneQuest (mqracing) for the information
at this link below
http://www.diytube.com/phpBB2/viewtopic.php?f=6&t=3694
The core size for the A-470 is an EI-112 and the stack height is 1.875".
Standard holes. The grade of lamination is 29 gauge M6.
Core Dimensions
A470 Windup details
A470 Windup schematic
David Hafler's patents also seem to have a lot of information on the winding
techniques ( I glanced at one of them - it was quite dense reading) -
https://patents.google.com/patent/US2710312A/en
https://patents.google.com/patent/US2815408A/en
David Hafler's interview in the Vacuum Tube Valley magazine (issues 14, 15) -
https://web.archive.org/web/20181126083637/https://hafler.com/pdf/interview-with-hafler-pt1.pdf
https://web.archive.org/web/20190303161742/http://www.hafler.com/pdf/interview-with-hafler-pt2.pdf
David Hafler (seems to he may be referring to the A430, but he also says others like A470 are similar) -
The Dynaco design had something that was very rarely done, I had not seen any-body do it in output transformers. It inverted part of the winding. The coil was spun in the opposite direction and windings were put in parallel, criss-crossed sections. It is a little hard to describe. It was interweaved through a parallel connection rather than series connection which I had not seen other transformers use.
So the transformer had four winding sections. The first and third were wound in opposite phase and inserted backwards in order to make it work out. The secondary came in between the first and third or second or fourth sections. This is hard to describe without drawing a diagram. You could probably find that patent very easily if you wanted to look it up. It shows that both series had parallel arrangements.
