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Elmer, need help! Electronics question
I apologize for this being a little off topic. I've recently installed
a cb radio and am picking up lots of alternator whine that is coming in from the antenna. I've ordered an alternator noise suppressor (http://www.crutchfield.com/S-VqGuUio...nfo&i=127ANS80) which arrives next week. Looking at the online installation instructions (http://akamaipix.crutchfield.com/Man...7/127ANS80.PDF), it indicates that I may have to add a "10000 or 50000 mfd capacitor" to completely block the noise. The installation looks simple enough, but where do I buy one? I've searched the web but can't find it. Does "mfd" translate to another measurement? Can anyone point me in the right direction? Thanks in advance. |
wrote in message indicates that I may have to add a "10000 or 50000 mfd capacitor" to completely block the noise. The installation looks simple enough, but where do I buy one? I've searched the web but can't find it. Does "mfd" translate to another measurement? Can anyone point me in the right direction? Thanks in advance. http://www.digikey.com/scripts/dksea...tors&site=u s http://www.ecovantageenergy.com/cata...s/item1591.htm http://www.cde.com/ http://www.tecategroup.com/?referrer=Google_Main B.H. |
ADONIS,
How do you know that the Alternator Whine is coming in from the Antenna ? .. Turn the Radio On and the Volume Up so that you can clearly hear the Whine. .. Disconnect the Antenna from the CB Radio does the Sound of the Whine Stop or is it Greatly Reduced ? + Then in-fact the Antenna is the Source of your Noise {Whine} Problem. - However if the Whine is just as Loud as when the Antenna is 'connected' then the Problem is elsewhere. .. Two Possible Elsewheres : * The CB Radio Ground. - Recheck your Radio's Case Ground Connection + Use a 4"-8" piece of Braided Webbing as a Ground Strap between the Auto's Frame and the Radio's Case. * The DC Power Input Wires. + Use a Noise Suppression Capacitor on both DC Power Leads going to the Radio. + Wrap the DC Power Leads in Foil. .. Mobile Radio Install Tips - by Stu Olson http://www.stu-offroad.com/cb/cb_install-1.htm .. CB Radio RF Noise Suppression http://www.stu-offroad.com/cb/cb_install-4.htm http://www.roity.com/rc/rfi.html .. Eliminating Noise in Automotive Sound Systems http://www.koyote.com/personal/duncan/noise.htm .. Solving Ignition Noise RFI - by the ARRL http://www.arrl.org/tis/info/rfiignit.html .. Automotive Interference and Installation - by the ARRL http://www.arrl.org/tis/info/rficar.html .. PARTS SOURCE : * INSTALLER.Com http://www.installer.com/acc/ PCAP50 - 50,000 mfd Filter Capacitor PAF80 - 80,000 mfd Filter Capacitor PDF4 - 4 Amp Noise Filter * CRUTCHFIELD.Com http://www.crutchfield.com/S-yZLLPt7...g=181150&avf=Y PAC ANS-80 - In-line Alternator Noise Filter PAC SNF-3 - Source Noise Filter .. You may wish to post your Questions about CB Radio Instalation on the Rec.Radio.CB NewsGroup http://groups-beta.google.com/group/rec.radio.cb .. |
matt weber wrote:
On 28 Jan 2005 16:37:51 -0800, wrote: snip Thanks in advance. mfd=Microfarads or uF. In other words buy yourself a nice big electrolytic cap (about 30wvdc for make sure it surives) and put it across the leads. Get it at Ratshack, or any electronic parts supplier. If it says mfd it should mean mili-farads - not micro-farads. -A -- ~/.signature |
In article ,
Al Arduengo wrote: If it says mfd it should mean mili-farads - not micro-farads. Nobody uses millifarads, except maybe the boom car crowd. "mfd" or more commonly "mf", prior to (the 1960's) metrification/SI rationalization meant Microfarads. And picofarads were "mmf" micro micro farads. Mark Zenier Washington State resident |
Al Arduengo wrote:
mfd=Microfarads or uF. In other words buy yourself a nice big electrolytic cap (about 30wvdc for make sure it surives) and put it across the leads. Get it at Ratshack, or any electronic parts supplier. If it says mfd it should mean mili-farads - not micro-farads. Not in the USA. ================================================ Only metric prefixes for 10+6 or more have an upper-case abbreviation (e.g., M = 10+6, G = 10+9, etc.). In particular, note that the prefix m indicates 10-3 and M indicates 10+6. The difference between an upper-case M and a lower-case m is nine orders of magnitude! One should be warned that American manufacturers of capacitors often use "mF" or "MF" to indicate microfarads, a practice that is both incorrect and misleading. The proper abbreviation for "kilohertz" is "kHz": only the "H" is upper case. Note that the proper abbreviation for "second" is "s", not "sec". The same abbreviation is used for the singular and plural form of a unit. A period is not placed after an abbreviated unit, unless it is at the end of the sentence. http://www.rbs0.com/tw.htm ================================================== ================================================== * mF: Milli-Farad, 1x10-3 Farad (1,000th of a Farad) - uncommon * uF: Micro-Farad, 1x10-6 Farad (1,000,000th of a Farad) * mF: Micro-Farad, a very, very old term, still sometimes used in the US (True!) - Causes much confusion. * ufd: Micro-Farad, another very old term, still used in the US * mfd (or MFD): Yet another antiquated term - US again! * nF: Nano-Farad, 1x10-9 Farad (1,000,000,000th of a Farad) - Common everywhere except the US * pF: Pico-Farad, 1x10-12 Farad (1,000,000,000,000th of a Farad) * mmF: Micro-Micro-Farad, another extremely old term, also still used sometimes in the US http://sound.westhost.com/beginners.htm ================================================== = mike |
Thanks for the replies... So what does 50,000 mfd translate to in uF?
..5? .05? Mark Zenier wrote: In article , Al Arduengo wrote: If it says mfd it should mean mili-farads - not micro-farads. Nobody uses millifarads, except maybe the boom car crowd. "mfd" or more commonly "mf", prior to (the 1960's) metrification/SI rationalization meant Microfarads. And picofarads were "mmf" micro micro farads. Mark Zenier Washington State resident |
maybe this will help
base unit one farad millifarad = 1/1000 farad or a thousands of a farad (seldom used for capacitors) microfarad = 1/1,000,000 farad or a millionth of a farad unfortunate the mixup of the prefixs "m" In some measurements such as current ..001 amp is expressed as one mA m meaning milli ..000001 amp is expressed as one uA u meaning micro So back to your original question - you need to ascertain the use of m A 50,000 millifarad is a whopping capacitor and not likely So it was probably 50,000 microfarads Hope that helps -- Caveat Lector wrote in message oups.com... Thanks for the replies... So what does 50,000 mfd translate to in uF? .5? .05? Mark Zenier wrote: In article , Al Arduengo wrote: If it says mfd it should mean mili-farads - not micro-farads. Nobody uses millifarads, except maybe the boom car crowd. "mfd" or more commonly "mf", prior to (the 1960's) metrification/SI rationalization meant Microfarads. And picofarads were "mmf" micro micro farads. Mark Zenier Washington State resident |
In article ,
(Mark Zenier) wrote: In article , Al Arduengo wrote: If it says mfd it should mean mili-farads - not micro-farads. Nobody uses millifarads, except maybe the boom car crowd. "mfd" or more commonly "mf", prior to (the 1960's) metrification/SI rationalization meant Microfarads. And picofarads were "mmf" micro micro farads. Mark Zenier Washington State resident That's not what I see in most articles or catalogs. 1 F is 1 farad 1 mF is .001 or 1x10^ -3 or 1 milli-farad 1 uF is .000,001 or 1 x 10^ -6 or 1 micro-farad 1 nF is .000,000,001 or 1 x 10^ -9 or 1 nano-farad 1 pF is .000,000,000,001 or 1 x 10^ -12 or 1 pico-farad Many capacitors are in mF in industrial power supplies. Got to get the current step response down to 20 Hz in some cases. -- Telamon Ventura, California |
In article ,
Telamon wrote: In article , (Mark Zenier) wrote: In article , Al Arduengo wrote: If it says mfd it should mean mili-farads - not micro-farads. Nobody uses millifarads, except maybe the boom car crowd. "mfd" or more commonly "mf", prior to (the 1960's) metrification/SI rationalization meant Microfarads. And picofarads were "mmf" micro micro farads. Mark Zenier Washington State resident That's not what I see in most articles or catalogs. 1 F is 1 farad 1 mF is .001 or 1x10^ -3 or 1 milli-farad 1 uF is .000,001 or 1 x 10^ -6 or 1 micro-farad 1 nF is .000,000,001 or 1 x 10^ -9 or 1 nano-farad 1 pF is .000,000,000,001 or 1 x 10^ -12 or 1 pico-farad Many capacitors are in mF in industrial power supplies. Got to get the current step response down to 20 Hz in some cases. Man, I just dug out an older EEM (Electronics Engineers Master catalog) and it's a MESS. Even in 1993, some outfits were still using MFD for microfarads. Millifarads are probably an artifact of Globalization (ie. of the outfits that used MFD for uF in 1993 are probably now empty factories in the US midwest after all their equipment got auctioned off to somebody from Canton). Likewise nanofarads are pretty much of an indicator the your capacitor was made by a European based manufacturer. I'd only expect to see millifarads on big "Computer Electrolytics", those beer can size (or bigger) with screw terminals. The bottom line for project building hobbyists is that you need to take into account when and where the magazine article or book was written. There's a lot of stuff out there that's old enough to be really confusing. (Several years back, I had an e-mail converstation with a guy who was trying to find parts for a transistorized VLF reciever, and the writeup included how to use it for detecting atmospheric atomic bomb tests, which quit before 1963). Mark Zenier Washington State resident |
In article .com,
wrote: Thanks for the replies... So what does 50,000 mfd translate to in uF? ..5? .05? 50,000 uF. Probably about the size of small can of V8 juice, given the voltage rating you'd use in a car (16 or 25 volts?). The newer they are, the smaller they get, so I might be showing my age. Mark Zenier Washington State resident |
Today mF most often means millifarad.
But in years past mF meant micro, as in uF, farad. Some diagrams as recent as the late 1990s still used mF to equal uF. Conversly, before the mid 1990s, no one but the military EMP research labs had Farad or milliFarad caps. I still remember when I saw my first .47F capacitor. Kind of freaked me out. I used a couple of 0.47 caps to replace the lithium backup cells in my R2000 and my IC-28A. If I had a few $100 to spare, I would be temtped to buy one of the several Farad caps designed for the automotive crowd. A cap that size would allow me to coast through most power glitches. Terry |
m II wrote:
Al Arduengo wrote: mfd=Microfarads or uF. In other words buy yourself a nice big electrolytic cap (about 30wvdc for make sure it surives) and put it across the leads. Get it at Ratshack, or any electronic parts supplier. If it says mfd it should mean mili-farads - not micro-farads. Not in the USA. It seems the times are changing. 'Mfd' has always meant micro-farads in the US but with the large capacitors being made now, 'uf' is becoming a better notation so it's not confused with 'milli-farads' for the big caps'. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Mark Zenier ) writes: In article .com, wrote: Thanks for the replies... So what does 50,000 mfd translate to in uF? ..5? .05? 50,000 uF. Probably about the size of small can of V8 juice, given the voltage rating you'd use in a car (16 or 25 volts?). The newer they are, the smaller they get, so I might be showing my age. The first power supply I built, in the early seventies, I bought at a hamfest a 10,000uF capacitor with about a 16v rating. Big stuff at the time. It's the size of a Coke can, and has those screw terminals. "Computer grade" was what similar capacitors in the surplus store ads were called. Pretty useless these days, given that you can get bigger capacitance and a higher voltage rating in a much smaller package. Micahel |
Thanks Mark! I got my noise filter today and will get it hooked up
this weekend. I'm hopeful that it resolves the alternator whine by iteself, but I expect it will take a cap to totally fix it. |
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