I would suspect they designed the circuit correctly to suppress those oscillations, but I don't know. I don't think Ramsey provides a schematic on their site, but there is a patent associated with the product, so maybe some information about the circuit could be gleaned from the patent description.
It might be interesting to take a sniff of this device with a spectrum analyzer... On Thu, Sep 24, 2009 at 9:44 AM, John Woodgate <[email protected]> wrote: In message <[email protected]>, dated Thu, 24 Sep 2009, American Idle <[email protected]> writes: I have always wanted to buy and use the Ramsey 'Passive Airband Monitor' on a plane trip http://www.ramseyelectronics.com/cgi-bin/commerce.exe?preadd=action&key= ABM1 but I don't think I'd ever be able to successfully explain the finer points of the local oscillator-free design to the flight crew, and probably end up getting ejected from the flight for not complying with their instructions to turn it off during takeoff... Amplified crystal set, I suppose. But how do you know the audio amp isn't oscillating at VHF? Some of the BTL chips are very intolerant of capacitive load. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Things can always get better. But that's not the only option. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
