[Kenwood] Kenwood TS-130S

[Clif Holland]

14v 80ma

Clif Holland KA5IPF
www.avvid.com




----- Original Message ----- 
From: "Bryan Swadener" <bswadener at yahoo.com>
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
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