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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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15th Nov 2019, 1:31 pm | #1 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,614
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Mystery radio circuit?
I found this in an old scrapbook, drawn by myself, probably around 1975 but I have no idea what it is part of - does anyone recognise it?
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Richard Index: recursive loop: see recursive loop |
15th Nov 2019, 1:49 pm | #2 | |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Mystery radio circuit?
Quote:
The mixer IC is a classic crossed collector 4 quadrant multiplier type Gilbert cell with features analogous to the MC1496. Perhaps it was an experiment to play with the mixer IC , a fet L/O and a grounded gate RF amplifier. |
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15th Nov 2019, 4:49 pm | #3 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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Re: Mystery radio circuit?
Topband or 80m direct-conversion receiver front-end?
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15th Nov 2019, 6:17 pm | #4 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,015
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Re: Mystery radio circuit?
1.4MHz IF Product Detector got my vote.
Or on reflection maybe not... why would you need any padder capacitors on that. |
17th Nov 2019, 1:58 pm | #5 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,205
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Re: Mystery radio circuit?
There's an antenna in the schematic, so it must be a receiver of some kind.
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17th Nov 2019, 2:44 pm | #6 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,911
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Re: Mystery radio circuit?
The capacitance of those MVAM varactors points at medium wave, possibly topband.
Lack of outputs shown for the mixer chip misses some clues that could have been there. The padder suggests it is the mixer stage of a superhet. David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
17th Nov 2019, 6:19 pm | #7 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,015
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Re: Mystery radio circuit?
I don't see that as antenna, all 3 lines would be equal length in my version of that symbol.
That looks like it is just "sig in" to me. |
17th Nov 2019, 7:03 pm | #8 |
Triode
Join Date: Sep 2014
Location: Ringwood, Hampshire, UK.
Posts: 29
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Re: Mystery radio circuit?
You will find this very same circuit on page 312 of Elektor march 1976 via the Americanradiohistory. com website. Its the front end of a Super Plam phased lock loop type receiver.
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18th Nov 2019, 11:16 am | #9 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,614
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Re: Mystery radio circuit?
Superb detective work!
Now I just have to wonder why I copied the diagram and what I was trying to do?
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Richard Index: recursive loop: see recursive loop |
18th Nov 2019, 2:19 pm | #10 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: Mystery radio circuit?
Someone else's copy; save a few pennies?
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