I've been asking around about any technical information on the SRF 59, specifically the Sony CXA1129N integrated circuit that forms the heart of the receiver. I finally ran across one person, Robert Culter, who has been interested in the SRF 59 and the Sony IC for some time and has been able to gather quite a lot of information about it. Bob has given me permission to include his remarks, and I'm simply posting his complete email, with an additional postscript at the end. If you have a technical bent and have been interested in the electrical workings of the SRF 59, this should answer a lot of questions. Nick Hall-Patch, being an IEEE member, has obtained a copy of the paper referenced in Bob's remarks, and Nick will probably eventually have more to say about this Sony IC and its use in the SRF 59.
Best regards, Steve NE Oregon Hi Everyone, (January 4, 2008) The Sony SRF59 is indeed a very interesting receiver. The operation of the CXA1129N chip (FM/AM) is described in great detail complete with section schematics in an IEEE paper: Advanced Low Voltage Single Chip Radio IC By Okanobu, Tomiyama, and Arimoto IEEE Transactions on Consumer Electronics, Vol. 38, No. 3, August 1992, pp. 465-475 If you can find this article in a technical library, it is worth the search. It can also be purchased through the IEEE Explore website (which I had to do eventually after I copied the article in a technical library, threw it away during a massive cleanup, and then discovered the SRF59 and just about went nuts trying to find the article again). The IEEE is quite serious about copyright, so I don't feel free to distribute the article without permission. There are a number of other Sony IEEE articles on sub-1V receiver ICs but this article seems to describe the CXA1129N chip directly. The CXA1129N chip has no published data sheet, either in English or in Japanese (I have looked everywhere). Sony does not sell the chip to other manufacturers in spite of the alleged stock by some Chinese websites. The above article mentions an AM-only version that was used in card-type receivers sold only in Japan. The CXA1129N is a phasing type IC but is not direct conversion. The FM IF frequency is 150 kHz and the AM IF frequency is 55 kHz. The phasing mixers (used for both bands) are driven by an LO that is divided by 2 to obtain quadrature outputs. Both mixer outputs are sent through 4th order active phase shift networks that maintains 90 degrees difference within 1 degree over the entire IF range of 50-250 kHz for both AM and FM. The AM section has three 2nd order biquad 55 kHz band pass filters (to replace external ceramic filters) and achieves an adjacent channel rejection of 35 dB. The chip will work down to 0.95VDC. The FM design seems similar to the Philips TDA7000, but the AM section is unique. Toshiba also has a 1-volt AM radio chip, but it has conventional operation. I very much appreciate the link to the SRF-PSY03 service manual. The circuit board does look identical to the SRF-59 that I have. There is a website discussing the various Sony receivers including the SRF-59 and also shows modifications for lower bass response: http://www.fixup.net/tips/srf49/srf49.htm . The SRF49 and SRF83 use the same CXA1129N chip. I have considered modifying an SRF59 for shortwave operation but do not know how high the chip will tune (no data sheet). The only way to get a chip is to take apart or modify one of the Sony radios. 73, Bob N7FKI (There appears to be a US Patent, 5020147, on the CXA1129. The patent does not have the partial schematics of the filter and delay circuits, so the IEEE article is still the best reference.) _______________________________________________ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
