Quote:
Originally Posted by wa2ise
]... and the chip died...    Went on ebay and ordered some TEA5710 chips from some outfit in China, expect them to arrive around July 15th... |
The chips arrived today, and after dealing with a bad soldering iron (it did heat, but not very hot) got the new chip in, and after a couple solder bridges and other stupidity, got it working. The new ceramic filter does have a fair amount of insertion loss (7dB), so AM stations are a little weaker than before, but there's enough AGC to make up for it in the TEA5710.
I decided to replace the loop antenna with a ferrite rod. Removed about 3/4th the turns off the coil to get it to peak on a station near 570KHz. And touched up the trimmer cap for the high end of the band (note the paper sticker identifying the purpose of the trimmers after I did some trial and error. :-)
Here's some characteristics of the ceramic filter. As I mentioned before, this filter came out of a first generation cell phone. Remember the cell phones of the 80's, the ones you could eavesdrop on with a scanner that could tune around 870MHz? Those used narrow band analog FM modulation, and used double conversion IF strips, the 2nd IF was 455KHz but the FM signal required a wideband filter, which I repurposed for wider than usual wideband AM reception. Many narrowband FM radios likely have such filters you could grab for this.