[TenTec] Bulb replacement in Model 238 Tuner

[Mike Hyder -N4NT-]

(In a factory mod for the Omni-C, Ten-Tec suggested replacing the #47
lamp/180 ohm series resistor with the 1892 lamp and 10 ohm series resistor.)
I tried 100 ohm and found the lamp much too dim.  A 27 or 33 ohm resistor
worked well for me.  I used a 1 watt resistor but a half watt resistor has
plenty of dissipation for this circuit.

73, Mike N4NT

----- Original Message -----
From: "Dr. Gerald N. Johnson, electrical engineer" <geraldj@isunet.net>
To: <gr1ns@aol.com>
Cc: <TenTec@contesting.com>
Sent: Saturday, June 15, 2002 10:13 PM
Subject: Re: [TenTec] Bulb replacement in Model 238 Tuner


> The 1813 and 1892 are practically the same lamp. 14.40 volts at .1 or
> .120 amps. I don't know but probably TenTec uses which ever one they
> have handy at the time of assembly. If you want longer lamp life look
> for a 28 volt lamp, like a 313, 757, 1864, 1818, 1820, or 1829. That's
> an easier change than adding a resistor. Otherwise the original lamp
> could have a series resistor or 68 to 150 ohms. 1 watt would be a
> suitable power rating. Its hard to predict resistor power dissipation,
> because the lamp resistance is so nonlinear.
>
> 73, Jerry, K0CQ