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FWIW the SB-102 uses two 1815 and one 47. The 1815s are wired across the 12V to ground, the 47 is wired in series with some of the tubes. That's what is hown schematically on my SB-102, and it is borne out tracing the circuit. Don't know about theSB-101 or HW series, but the 102 definitely uses both.<BR>
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<DIV id=SkyDrivePlaceholder></DIV>> From: kgordon2006@frontier.com<BR>> To: Heath@puck.nether.net<BR>> Date: Mon, 14 Jan 2013 09:32:44 -0800<BR>> Subject: Re: [Heath] Light bulbs for HW/SB transceivers<BR>> <BR>> On 13 Jan 2013 at 18:41, Glen Zook wrote:<BR>> <BR>> > They are not 12.6-volt bulbs. The pilot lamps are wired either in<BR>> > series with each other or are wired in the series-parallel arrangement<BR>> > with all of the tube heaters ("filaments"). The bulbs themselves are<BR>> > just plain old #47 and are available all over the place. Radio Shack<BR>> > has them (although slightly higher priced than the normal electronic<BR>> > parts outlets).<BR>> <BR>> Another point should be made here: there is a Heathkit service bulletin which <BR>> directly addresses the pilot lamp issue for the HW-101 or SB-100/101/102.<BR>> <BR>> Some kits were supplied with #44 pilot lamps, instead of #47 bulbs: the #44 <BR>> lamps draw 250 mA each, and thus unbalance the series-parallel filament <BR>> string.<BR>> <BR>> The #47 bulbs draw 150 mA each, which is correct.<BR>> <BR>> Always use #47 pilot lamps, and make sure your rig does not have #44 <BR>> lamps in it instead.<BR>> <BR>> Ken W7EKB<BR>> <BR>> _______________________________________________<BR>> Heath mailing list<BR>> Heath@puck.nether.net<BR>> https://puck.nether.net/mailman/listinfo/heath<BR></DIV> </div></body>
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