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Texas Star 250 HD Resistor
- Thread starter RobInSTL5150
- Start date
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- texas star 350
![IMG_3726[1].JPG](/data/attachments/55/55843-b1f38757f73dc9a7818dc58c4d0dc2ca.jpg)
![IMG_3725[1].JPG](/data/attachments/55/55847-84b3550bcddbfd6a9c5eb8ee5eb40a17.jpg)
Looking quickly on my phone, that looks like one of the 10 ohm resistors, the bad news is that the transistor next to it is probably toast.
Expensive to replace nowadays.
73
Jeff
Expensive to replace nowadays.
73
Jeff
Last edited:
I did have to correct my OP it is a 250 HD and only schematic I have is the 350 HD. Poor resistor is so toast it's just ash looks like it had a major overheat.
That resistor connects the transistor's base lead to ground. The base is the input. Voltages there are fairly low, and the current this will push through a 10-ohm resistor won't overheat it.
Until someone causes the RF transistor to fail. They tend to short between the collector and the base. The collector is the output side of the transistor, connected to the 12-Volt main power. This shoots 12, or 13.8 or whatever the power source is the wrong way out of the transistor's input side. Twelve volts applied to a 10-ohm resistor will release 14.4 Watts of heat. Naturally, the half-Watt resistor in the pic gets toasty from a 28-to-one overload factor.
The real news is the cost and risk of replacing the transistors. The resistor alone is the cheap part of any real repair.
73
Until someone causes the RF transistor to fail. They tend to short between the collector and the base. The collector is the output side of the transistor, connected to the 12-Volt main power. This shoots 12, or 13.8 or whatever the power source is the wrong way out of the transistor's input side. Twelve volts applied to a 10-ohm resistor will release 14.4 Watts of heat. Naturally, the half-Watt resistor in the pic gets toasty from a 28-to-one overload factor.
The real news is the cost and risk of replacing the transistors. The resistor alone is the cheap part of any real repair.
73
That's my thought since it sure seems obvious the pill went and have to weigh the cost of that to see if this unit it worth fixing or not. I do have some of the HG pills here but not for the 250 and remember those running around 90 total.
Greg T
WDX-945 (Jazz Singer) Upper Peninsula of Michigan
Here are your options for final replacement. At least HG now makes a 2290. The Toshiba parts are very very expensive. Good luck.
www.rfparts.com
2SC2290A-MP Transistor, Matched Pair, Toshiba
2SC2290A-MP Transistor, Matched Pair, Toshiba