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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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22nd Mar 2020, 12:36 am | #1 |
Diode
Join Date: Mar 2020
Location: London, UK.
Posts: 4
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Sanyo RP-1270 circuit help
Hi all.
I want to make my own Sanyo RP-1270 based on the circuit design I found on the internet. I used to listen to it when I was kid and want to make it now as a circuit building practice and piece of history to keep. I have some stuff I don't understand about the circuit like where is the ferrite rod antenna? How do I make one? Where is the variable capacitor? Attached is the circuit if anyone can leave some comments on it please. Thanks a lot. Last edited by AC/HL; 22nd Mar 2020 at 2:17 pm. Reason: Copyright schematic removed |
22nd Mar 2020, 2:16 pm | #2 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
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Re: Sanyo RP-1270 circuit help
Radio museum isn't usually happy about their documentation being publicly posted...... or didn't used to be for sure.
If you're building this from scratch your biggest problems will be the mixer and IF transformers, otherwise it's all pretty standard stuff for the period. How T3 does anything useful feeding a shorted primary in that IF transformer is beyond me- I can only assume it's a misprint and there's a missing capacitor!
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....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
22nd Mar 2020, 2:18 pm | #3 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
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Re: Sanyo RP-1270 circuit help
As above, the schematic is available on radiomuseum.org.
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23rd Mar 2020, 12:03 am | #4 | |
Diode
Join Date: Mar 2020
Location: London, UK.
Posts: 4
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Re: Sanyo RP-1270 circuit help
Quote:
What is a mixer? Is it the same as oscillator? Why you would be worried about them? Do you mean they are not manufactured anymore? |
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23rd Mar 2020, 11:30 am | #5 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
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Re: Sanyo RP-1270 circuit help
tareqam.
Members here are always willing to offer help, but you could help yourself by reading about (Superhet)erodyne Receiver theory.
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
23rd Mar 2020, 12:05 pm | #6 |
Diode
Join Date: Mar 2020
Location: London, UK.
Posts: 4
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Re: Sanyo RP-1270 circuit help
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23rd Mar 2020, 1:08 pm | #7 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
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Re: Sanyo RP-1270 circuit help
It's unlikely that the specific mixer and IF transformers could be obtained new, now, and the same will go for all parts of the set though generic small components (resistors, capacitors, transistors etc) that would fit an original circuit board are readily available. Parts like the transformers with multi pin connections will be more difficult to source unless you are not constrained by originality in appearance and fitting.
Specific answer to mixer/oscillator question (do follow Station X's recommendations though): The (local) oscillator provides a variable frequency signal differing from the frequency of the signal being received by a fixed amount. This constant difference frequency is produced when the signal and oscillator frequencies are combined in the mixer. It's done that way because it's much easier to provide high gain and selectivity in a tuned amplifier at a fixed frequency than at a variable frequency depending on the station. The process brings its own ragbag of new problems (mostly spurious responses and frequency tracking problems) but overall it's worth doing. The mixer is simply the device which mixes the two frequencies together. Just for added confusion, most consumer product radios (as does this one) have a combined mixer and oscillator stage where one device carries out both functions!
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....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
24th Mar 2020, 11:29 am | #8 |
Diode
Join Date: Mar 2020
Location: London, UK.
Posts: 4
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Re: Sanyo RP-1270 circuit help
I am not worries about the parts being original. just want to replicate the circuit.
Herald1360, Your comment is very informative. thanks a lot 💚📻💚 |
25th Mar 2020, 5:39 pm | #9 |
Nonode
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,853
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Re: Sanyo RP-1270 circuit help
Hi!
The "AM Radio" kits offered by the Far Eastern vendors use almost identical components to the ones originally used by Sanyo to make the RP–1270, down to the a.f. input and output transformers! https://www.ebay.co.uk/itm/184213280368 You'd be hard pushed to tell the difference between these components and the ones Sanyo used, apart from the cosmetic items of course! Chris Williams PS! You'd probably be able to get a set from another Member that may be too bad cosmetic–wise to be worth restoration in it's own right for the coils, ferrite rod, tuning gang, etc., etc., ask on here!
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It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! Last edited by Chris55000; 25th Mar 2020 at 5:44 pm. |