HFU HF Underground
Technical Topics => Equipment => Topic started by: Oliver on July 27, 2015, 2143 UTC
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Rockwell Collins Filter Products specializes in designing mechanical filters to meet your unique and evolving requirements. We produce two different types of mechanical filters. For frequencies between 100 kHz and 700 kHz, we create filters made from rods resonating in a torsion mode. For frequencies below 100 kHz, we use flexure mode bar resonators. Our filters can achieve bandwidths from 0.05 to 5 percent.
Over the past several years, we have seen a dramatic reduction in demand for narrowband analog filters. Due to this and other economic reasons, Filter Products will be discontinuing its mechanical filter products in the near future.
http://www.rockwellcollins.com/Capabilities_and_Markets/More/Rockwell_Collins_Filters.aspx
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Too bad. That's going to be rough on the few remaining companies like Palstar that still used mechanical filters. My Palstar R30C has a Murata wide ceramic (also discontinued) and Collins narrow mechanical filter. Great combination for audio quality and blocking adjacent signals. I seldom heard the QRM and crosstalk other DXers complained about from WYFR when they were active on the funny bands, or LSB pesquitoes on 6925 when a pirate was on USB.
Some of the earlier web SDRs I tried couldn't quite match this performance, although the more recent SDRs seem to have solved that problem and offer some very flexible controls for digging out signals.
I'm not sure about the subjective audio quality issue. Very squishy area, especially with tube aficionados. Can't claim I ever heard the differences in radios, although I could in my guitar amps.
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Sad to see some of the classic solid state technology go the way of the Dodo.
The only positive is that solid state parts (at least since the Germanium transistor days and paper capacitor days) usually have a long lifetime. I'm sure there will always be some of them socked away in a warehouse somewhere.