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 Post subject: inrush current limiters
PostPosted: Jan Sat 31, 2004 9:42 pm 
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Is there any downside to installing one? <BR>I'm thinking I ought to, on the sets I use regularly. <P>In the same vein: If I do install one, is it overkill to add a fuse also?<P>CB<P>------------------<BR>


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 Post subject: inrush current limiters
PostPosted: Jan Sat 31, 2004 10:00 pm 
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Hi Christopher,<P>The only things to watch out for are the fact that they run hot, so keep them away from anything that might be damaged by heat. Best to mount them out in the open (under the chassis, obviously), on a terminal strip. Don't get them up close to a heat sink, like the chassis. They won't work properly if you do.<P>The ICL is not a substitute for a fuse. Still need the fuse.<P>ICL's are properly called Negative Temperature Coefficient (NTC) Thermistors. Excellent info on the Thermometrics site <A HREF="http://www.thermometrics.com" TARGET=_blank>http://www.thermometrics.com</A> . Their CL series is commonly used in vintage sets. Data sheet at <A HREF="http://thermometrics.com/assets/images/cl.pdf" TARGET=_blank>http://thermometrics.com/assets/images/cl.pdf</A> in PDF format.<P>There have been several threads on this subject here on the Forum.<P><P>------------------<BR>73 de Leigh W3NLB<BR> <A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A>


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 Post subject: inrush current limiters
PostPosted: Jan Sat 31, 2004 10:02 pm 
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The fuse and ICL perform entirely different functions.<P>The fuse is a protection against excessive current draw caused by component failure: shorted filter caps, gassy output tube, rectifier tube failures, etc.<P>The ICL limits the inrush current on power up, it does nothing to limit current after it has warmed up. A short in the set only makes the device hotter, lowering its resistance, so it provides no protection for failures!<P>Most tube filament or pilot lamp failures occur at turn on, due to the low resistance of a cold filament. The ICL limits the current surge on the filaments at turn on. For sets with solid state rectifiers, the ICL also reduces the initial charging surge on the filter caps and rectifiers.<P>So, yes, use both. Especially the fuse.<P>Pete<P>------------------<BR>


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 Post subject: inrush current limiters
PostPosted: Feb Sun 01, 2004 4:28 am 
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Okay, will do. Thanks for the advice.<P>One more question: How about putting both ICL and fuse in a box at the wall outlet, then plugging the radio into it? Essentially, I'd be building a specialized power strip, leaving the radio unmodified. It'd be separate from the chassis, so there'd be no heat issue. Any reason not to?<P>------------------<BR>


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 Post subject: inrush current limiters
PostPosted: Feb Sun 01, 2004 5:00 am 
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Peter Bertini wrote:
<font>quote:</font><HR>Originally posted by Christopher Bonanos:<BR><B>Okay, will do. Thanks for the advice.<P>One more question: How about putting both ICL and fuse in a box at the wall outlet, then plugging the radio into it? Essentially, I'd be building a specialized power strip, leaving the radio unmodified. It'd be separate from the chassis, so there'd be no heat issue. Any reason not to?<P></B><HR>
<P>Excellent ideal. They sell similar devices on eBay for about 30 bucks a whack. <IMG SRC="http://antiqueradios.com/forums/smile.gif"><P>Pete<P><P>------------------<BR>


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 Post subject: inrush current limiters
PostPosted: Feb Mon 02, 2004 12:46 am 
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Okay! Thanks again for the advice.<P>Finally: Are any particular thermistor specs appropriate to this purpose? That spec sheet has twenty different options.<P>And: How big a fuse? One amp? <P>CB<P>------------------<BR>


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 Post subject: inrush current limiters
PostPosted: Feb Mon 02, 2004 12:50 am 
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Hi Chris,<P>The most commonly-used part is the CL-90. Rated 2 amps max, which will handle any vintage radio except the really huge ones.<P>Ordinarily the fuse would be sized at twice the normal current draw of the radio. Power consumption is frequengly given on the schematics, or you can measure it. You can use a smaller rating (1.5x) if you use a slo-blo rather than standard.<P>------------------<BR>73 de Leigh W3NLB<BR> <A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A>


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 Post subject: inrush current limiters
PostPosted: Feb Mon 09, 2004 10:54 pm 
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I've done it both ways, and Bryant & Cones (the TransOceanic experts) recommend installing them in TO's. Go here, <BR> <A HREF="http://www.ametherm.com/Inrush_Current/welcome.html" TARGET=_blank>http://www.ametherm.com/Inrush_Current/welcome.html</A> <BR> and check out what they have. I like the higher resistance, low current models. You won't find these at Mouser or Allied. Pick a bunch, then click on "SAMPLES" They'll send you a dozen each of 5 different types--FOR FREE!!! They may call and verify your request. Just tell them you restore old radios and heard these might be good to try.<BR>The price is right!<P>------------------<BR>OZ


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 Post subject: inrush current limiters
PostPosted: Feb Mon 16, 2004 8:18 pm 
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Peter Bertini wrote:
<font>quote:</font><HR>Originally posted by OZ132HOME:<BR><B>I've done it both ways, and Bryant & Cones (the TransOceanic experts) recommend installing them in TO's. Go here, <BR> <A HREF="http://www.ametherm.com/Inrush_Current/welcome.html" TARGET=_blank>http://www.ametherm.com/Inrush_Current/welcome.html</A> <BR> and check out what they have. I like the higher resistance, low current models. You won't find these at Mouser or Allied. Pick a bunch, then click on "SAMPLES" They'll send you a dozen each of 5 different types--FOR FREE!!! They may call and verify your request. Just tell them you restore old radios and heard these might be good to try.<BR>The price is right!<P></B><HR>
<P>In my case, I used my magazine title, and ended up with a sales rep. pounding at the door at 8:00AM one morning. My wife was still ranting when I got home (her day off, was trying to sleep in <IMG SRC="http://antiqueradios.com/forums/smile.gif"> )<P>At least he left the samples.<P>Pete<P>------------------<BR>


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 Post subject: inrush current limiters
PostPosted: Feb Mon 16, 2004 9:46 pm 
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Location: Gainesville, Florida
Not sure what you all are wishing but what is the difference if using an interruptable wall outlet sold everywhere for cheap? I know that thermisters are used in sensitive telephone circuits to protect them from shorts across an extentions wire pair. Dont know the design on the PCB but probably conduct at temperature to ground any low resistance currents when the pair is shorted. The older phone systems would blow a fuse, a time consuming event to say the least. These shorts are caused physically external of the circuit. This example is as a protection device. I dont see the application for a radio because the thing would just quit working all together. I would rather have a wall protection device for this reason.


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 Post subject: inrush current limiters
PostPosted: Feb Mon 16, 2004 10:05 pm 
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Hi Amp,<P>Tubes experience high inrush current due to the positive temperature coefficient of the filament. When cold, the resistance is lower, and the current higher, than when the tube is operating at full filament temperature. This high current is what causes the filament to burn out, just like in a light bulb.<P>The purpose of an ICL is to introduce an additional resistance in the primary of the transformer for a few seconds following power-up, to reduce this initial current. Once the ICL heats up, its resistance drops, and the current into the radio increases to its normal level. <P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR> <A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A>


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 Post subject: inrush current limiters
PostPosted: Feb Mon 16, 2004 10:41 pm 
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Location: Circleville, OH, USA
A GFI is not a fuse. It compares the current going to the appliance on the hot wire with that returning on the neutral. If there is any unbalance, it trips. Unbalance is caused by current flow through a path other than the return (i.e. your body). A short in the set would not create any unbalance.<BR>A GFI might be a good idea for AA5 sets, but an iso transformer is better. <P>------------------<BR>


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 Post subject: inrush current limiters
PostPosted: Feb Tue 17, 2004 12:44 am 
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I missed understood that time. No time to read today. Just brushed thru too kwikly


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 Post subject: inrush current limiters
PostPosted: Feb Wed 18, 2004 7:07 pm 
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Location: La Porte, IN, USA
tubeAMP, Slow dow. Ya move too fast. Got to make the mornin' last....<P>------------------<BR>OZ


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 Post subject: inrush current limiters
PostPosted: Feb Wed 18, 2004 7:38 pm 
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A good day for Feelin' Groovy <IMG SRC="http://antiqueradios.com/forums/smile.gif"><P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR> <A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A>


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