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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions. |
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30th Sep 2018, 6:18 pm | #1 |
Octode
Join Date: Jan 2007
Location: Dorridge, West Midlands, UK.
Posts: 1,481
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Identifying a System A modulator
On the Bring and buy at Harpenden I bought a die cast box with some sockets on. When opening it up this weekend I found it contained a well built System A modulator based on 2 MC1496 chips with Crystals for 41.5 and 45Mhz all on a single board. I have not seen one of these before can anyone help with the origin of this and possibly point me to a manual or other info.
Many thanks Chris |
30th Sep 2018, 8:33 pm | #2 |
Nonode
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,573
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Re: Identifying a System A modulator
Hi.
I don't know if the design could be similar to this one here https://www.thevalvepage.com/project...at/modulat.htm It certainly has many things in common. Regards Symon. |
30th Sep 2018, 10:56 pm | #3 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Identifying a System A modulator
It's the David Looser circuit that appeared in a 1984 Practical Television magazine titled "A System A Modulator"
Uses two MC1496 modulator ICs and BFY90 transistors in the carrier oscillators. DFWB |
1st Oct 2018, 10:43 am | #4 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,431
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Re: Identifying a System A modulator
Thanks go to David for the reference.
https://www.americanradiohistory.com...UK-1984-10.pdf
__________________
Frank |
1st Oct 2018, 1:09 pm | #5 |
Octode
Join Date: Jan 2007
Location: Dorridge, West Midlands, UK.
Posts: 1,481
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Re: Identifying a System A modulator
Thanks to those who responded.
I found the article and it looks to be virtually identical. It is a nicely made PCB so I assume at some stage someone must have designed and sold the PCB perhaps as a kit. After some quick tests all seems to work so I and finished the case off and put some knobs on it. I now have another useful modulator for my 405 sets. Chris |