I assume you mean the markup. If you think that's high, just look at what a hospital charges for an Aspirin or a Band-Aid.
YMMV, -John ================ > That's criminal! > > Tom > ----- Original Message ----- > From: "J. Forster" <[email protected]> > To: <[email protected]>; "Discussion of precise time and frequency > measurement" <[email protected]> > Sent: Monday, June 17, 2013 12:43 PM > Subject: Re: [time-nuts] HP and other equipment failure > > > An Audiophool and his money are soon parted. > > -John > > =============== > > > >> The current distortion from simple transformer-rectifier-capacitor power >> supplies contains a lot of third harmonic content. In a 3 phase system >> (as are >> all distribution systems for commercial and industrial) the third >> harmonic >> ADDS >> in the neutral, or creates circulating currents in a delta >> configuration. >> These >> currents, as you mention, can get very large and were the cause of many >> transformer explosions in cities as these power supplies became common. >> The >> transformer designs had to be improved, but the PFC supplies make a big >> difference. >> >> How many of you have looked at the power line waveform, especially in an >> industrial or commercial area? Doesn't look much like a sine wave, does >> it? So >> it's pretty funny to see audiophile outlets >> (http://www.dedicatedaudio.com/power_outlets). >> >> Peter >> >> >> >> >> On 6/15/2013 6:56 PM, stan, W1LE wrote: >>> PFC to me is power factor correction, not only the classical power >>> factor to >>> minimize (VAR) volt-amp reactive component, >>> but also to remove the harmonic load current imposd on the electrical >>> power >>> system. >>> A '90's onward technique. in th 80's and 90's without the harmonic load >>> current reduction and having >>> a few 100 end items of equipment, each withtheir own a switch mode >>> power >>> supplly, >>> it was not uncommon to find hundreds of amps of the third harmonc on >>> neutra, >>> in the electrical power distribution system. >>> >>> Could be a serious EMC problem if you were dealing with voice grade >>> channels. >>> And people safety issues. >>> >>> Stan, W1LE Cape Cod >>> >>> >>> >>> On 15-Jun-13 5:52 PM, J. L. Trantham wrote: >>>> Sorry for the interruption but what is 'PFC'? >>>> >>>> Thanks. >>>> >>>> Joe >>>> >>>> -----Original Message----- >>>> From: [email protected] [mailto:[email protected]] >>>> On >>>> Behalf Of Poul-Henning Kamp >>>> Sent: Saturday, June 15, 2013 4:09 PM >>>> To: Robert Atkinson; Discussion of precise time and frequency >>>> measurement >>>> Cc: Perry Sandeen >>>> Subject: Re: [time-nuts] HP and other equipment failure >>>> >>>> In message >>>> <[email protected]>, >>>> Robert Atkinson writes: >>>> >>>>> While I agree with everything else you say, you CAN have too much >>>>> filter capacitance. At least where dc rectifier / filter (smoothing) >>>>> circuits are concerned. Increasing C causes increased ripple current >>>>> [...] >>>> And ripple current can be a major source of power-line frequency noise >>>> in >>>> all electronics. >>>> >>>> The main reason why switchmode power-supplies today (can) outperform >>>> linear >>>> power supplies with respect to noise, is because the legally mandated >>>> PFC >>>> correction eliminates the bridge-rectifier ripple harmonics. >>>> >>>> I would not hessitate to use a good quality switchmode to replace the >>>> linear >>>> supply in a HP5370B. >>>> >>>> I did some experiments a couple of years ago, with an audio-amplifier: >>>> I put a standard PFC corrector chip on the secondary side of the >>>> trafo. >>>> >>>> The overall result was not satisfactory, but the 50 Hz "sneer" >>>> we all know and hate was absent, and the "Tzoing!!!!!" power-on >>>> mechanical >>>> shock from the trafo was also eliminated, as was the consequent >>>> dimming >>>> of >>>> the lights ;-) >>>> >>>> The main reason not to do this, is that you need some physically >>>> gargantuan >>>> coils for a 10A+ PFC-switcher. >>>> >>>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> >>> ----- >>> No virus found in this message. >>> Checked by AVG - www.avg.com >>> Version: 10.0.1432 / Virus Database: 3199/5913 - Release Date: 06/15/13 >>> >>> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
