[Kenwood] Kenwood TS-130S

Mon Nov 21 17:33:08 EST 2011

OK. However, it's moot when using the 317L (100mA max) with 12V lamps. Filament-destroying inrush current pulses go away.
vy 73,
Bryan WA7PRC
--- On Mon, 11/21/11, Clif Holland wrote:
> From: Clif Holland
> Subject: Re: [Kenwood] Kenwood TS-130S
> To: Bryan WA7PRC, kenwood at mailman.qth.net
> Date: Monday, November 21, 2011, 2:25 PM
> 14v 80ma
>> Clif Holland KA5IPF
> www.avvid.com
>> ----- Original Message ----- From: Bryan WA7PRC
> To: <kenwood at mailman.qth.net>
> Sent: Monday, November 21, 2011 4:18 PM
> Subject: Re: [Kenwood] Kenwood TS-130S
>>> David,
>> They're just "Grain Of Wheat" lamps with a T1 (3mm
> diameter) bulb & wire leads. IIRC, Kenwood used
> 14V/25mA lamps. Your local hobby supply store should
> have them.
>> Their lifetime is determined by the supply voltage/current
> and the number of times you cycle the power on/off. 
> Each increase of 5% voltage/current results in a decrease of
> approximately 50% in lifetime. Likewise, a decrease of
> 5% voltage/current results in an increase of 50% in the
> lifetime.
>> The number of times you cycle the power on/off has an
> effect as well. Incandescent lamps have a low cold
> resistance. This results in an inrush current pulse of
> around 5X or more of the running current. This is a huge
> mechanical shock to the filament and causes early
> failure. Leaving it ON isn't practical but you can
> limit the inrush current with a simple current source. 
> The LM317L voltage regulator works well, is easy to
> implement, and costs pennies. The LM317L datasheet
> shows how to use it as a current regulator, using one
> resistor. Since the 317 will drop around 1.25V, use it
> with a 12V lamp on a 14V source. Mine's been working
> for many years... so far.
>> vy 73,
> Bryan WA7PRC
>> From: David KW4DH
> Subject: [Kenwood] Kenwood TS-130S
> To: kenwood at mailman.qth.net
>> Before I adventure inside the case of my TS-130S, is there
> a bulb to
> illuminate the S meter? I have gone back and forth over the
> schematic
> but I can't seem to find any indication.
>> David
> KW4DH