[Heath] Light bulbs for HW/SB transceivers

[Ron Oxley]

The SB-102 dial lamps are #1815 which is a 14 volt lamp.  They are wired in parallel across the 12.6 volt filament line.  The lamp used for regulation in the LMO power supply is also a #1815.  The meter lamp is a #47 which is a 6.3 volt lamp and wired across the 6.3 volt portion of the filament line.

73,
Ron, WM8Z
PH:  269-468-7780
 
RTO Electronics
601 E. 1st Street

Calexico, CA 92231

http://www.rtoham.com 





> From: kgordon2006 at frontier.com
> To: Heath at puck.nether.net
> Date: Mon, 14 Jan 2013 09:32:44 -0800
> Subject: Re: [Heath] Light bulbs for HW/SB transceivers
> 
> On 13 Jan 2013 at 18:41, Glen Zook wrote:
> 
> > They are not 12.6-volt bulbs.  The pilot lamps are wired either in
> > series with each other or are wired in the series-parallel arrangement
> > with all of the tube heaters ("filaments").  The bulbs themselves are
> > just plain old #47 and are available all over the place.  Radio Shack
> > has them (although slightly higher priced than the normal electronic
> > parts outlets).
> 
> Another point should be made here: there is a Heathkit service bulletin which 
> directly addresses the pilot lamp issue for the HW-101 or SB-100/101/102.
> 
> Some kits were supplied with #44 pilot lamps, instead of #47 bulbs: the #44 
> lamps draw 250 mA each, and thus unbalance the series-parallel filament 
> string.
> 
> The #47 bulbs draw 150 mA each, which is correct.
> 
> Always use #47 pilot lamps, and make sure your rig does not have #44 
> lamps in it instead.
> 
> Ken W7EKB
> 
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