PIN photo diodes can be very fast. --- On Thu, 1/19/12, Bob Camp <li...@rtty.us> wrote:
From: Bob Camp <li...@rtty.us> Subject: Re: [time-nuts] mixers for frequency measurement To: "'Discussion of precise time and frequency measurement'" <time-nuts@febo.com> Date: Thursday, January 19, 2012, 12:54 PM Hi PIN attenuator diodes = designed to be slow.. Bob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Thursday, January 19, 2012 3:44 PM To: time-nuts@febo.com Subject: Re: [time-nuts] mixers for frequency measurement On 01/19/2012 09:31 PM, Don Latham wrote: > Oh dear I had the wrong idea. Thought PIN's were designed for switching. > There is a breed of "ultra-fast" diode for protection in MOSFET > switching circuits like h-bridges. Any better? I'll replace the PIN diodes in our optical receivers at work, obviously they can't handle the gigabits we pass through them. Cheers, Magnus > Don > > Bob Camp >> Hi >> >> PIN = designed to be slow (not so good an idea) >> Avalanche = reverse breakdown (not a good conduction mode, noisy) >> >> Bob >> >> -----Original Message----- >> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On >> Behalf Of Don Latham >> Sent: Thursday, January 19, 2012 2:22 PM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] mixers for frequency measurement >> >> Soooo, PIN diodes? avalanche? >> Don >> >> Bob Camp >>> Hi >>> >>> Complicating the matter - the time it takes for the junction to go >>> from >>> full >>> on to full off also contributes to the noise. An ideal mixer would >>> switch >>> instantaneously.... It's always a tradeoff between various noise >>> sources. >>> >>> Bob >>> >>> -----Original Message----- >>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] >>> On >>> Behalf Of ed breya >>> Sent: Thursday, January 19, 2012 12:36 PM >>> To: time-nuts@febo.com >>> Subject: [time-nuts] mixers for frequency measurement >>> >>> Yes, they are Schottkys, just like the ones used in most mixers - but >>> much bigger and slower. They would have to be properly impedance >>> matched, and could be driven to higher power levels, with higher >>> diode conductance, so (I think) much lower noise. Of course, >>> amplifying up to higher power will add noise, so it's not "free" in >>> that respect. >>> >>> Ed >>> >>> Stefan wrote: >>> 1N5817 are schottky diodes. Wouldn't they saturate much earlier than >>> a 2N2222A? If saturation is the right word with a schottky diode... >>> >>> I wrote: >>> > 5 or 10 MHz could be made even better. I wonder how a ring of >>> matched >>> > 1N5817s would work at saturated power levels - maybe +20 dBm or so. >>> >>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> >> -- >> "Neither the voice of authority nor the weight of reason and argument >> are as significant as experiment, for thence comes quiet to the mind." >> R. Bacon >> "If you don't know what it is, don't poke it." >> Ghost in the Shell >> >> >> Dr. Don Latham AJ7LL >> Six Mile Systems LLP >> 17850 Six Mile Road >> POB 134 >> Huson, MT, 59846 >> VOX 406-626-4304 >> www.lightningforensics.com >> www.sixmilesystems.com >> >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.