Video posted May 27, 2026 :: https://youtu.be/eyBEh5sqnsQ
An experimeters look deep inside the CXA1019S -- a legendary Sony AM-FM-Audio chip.
Join us as try to better understand the signal path and perform testing with both instruments and ears.
Why the Sony CXA1019S AM-FM-Audio Chip is so great blog support notes
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Above — During the week prior to this 1 (May 24-30), the top 5 countries who visited our video support blog. Thank you for visiting us -- and many thanks to those who emailed us. We appreciate your feedback.
Above — A figure showing the main technical differences between AM and FM reception on a CXA1019-based receiver.
We no longer do medium wave DXing ( with exception of when we travel to Eastern Europe ), nor do we listen to local AM "talk-radio". Thus, we didn't cover the AM side of the CXA1019 IC. The signal path is similar except for the ferrite rod antenna, different VFO frequency and IF -- plus detecting audio happens in some form of an envelope detector. No detector details get shown in the datasheet.
Above — Our guess about the schematic of the AF stage within the CXA1019S chip. This guess comes from reviewing datasheets -- and the measures we took of the harvested IC.
The big dilemma is what parts go at the ? We've tried many times to make a suitable amp, but could not make it work well without driving the final pair with lots of current.
We'll hopefully figure this out one day. Making rail-rail output at low DC voltages seems to be an advanced skillset.
Q --- What digital radio comes closest to the CXA1019S?
Above — The Sony ICF-506 contains the Skyworks Si4831/35-B30 , a mechanically tuned 100% CMOS AM/FM/SW radio receiver IC. This is our radio and we took all the photos of it.
Above — A glimpse of the main PCB showing the receiver-on-a-chip digital IC (with mechanical tuning). We love this receiver and it's our main AC powered indoor FM receiver. It does take three 1.5 volt batteries for portable use, but battery life expectancy is lower than the CXA1019-based receiver.
The IC may also be used with a digitally tuned oscillator ( so can the CXA1019S), but this adds increased current consumption due to the the synthesiser/ PLL and the digital frequency display.
Above — The Sony ICF-506 contain a lovely speaker. A wonderful radio to own.
Q --- What's the best hand held FM receiver you've ever owned?
Above — The Sony SRF-49 <<Walkman>> Canadian Model is the best FM radio we've owned that cost under $100.00. The heart of this radio = CXA1129N AM-FM stereo IC with 2 local oscillators and a very clever IF filtration system; plus a stereo headphone-audio amp -- the Sanyo LA4537M.
Around 2002 or so, some mods were available in online forums and such -- we did 2 of these mods and 1 of our own. The 2 mods included increasing the output caps from 47 µF to 220 - 390 µF or so [to get more bass response] , plus changing the 2 de-emphasis capacitor values [to get more treble response].
We also added an external antenna jack to ours. At the ski hill, you could tune FM broadcast stations up and down the valley. The stereo field sounded massive. All with a single AA battery. Amazing technology from Sony back in the day.
Further -- we still have the headphones. These are the most sensitive and efficient headphones we've ever used-- and we now use them for our crystal radio set.
They blew away all the other headphones we've tried including some antique Western Electric high Z phones that were coveted & hyped by collectors.
Sadly, this receiver was loaned to relative who forgot it on the Sky Train and it's long gone. All of this content got stricken from the video.
...more updates later.....
-- thanks and Best!
Lid, MJ - Bars and Munchie