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TEXAS STAR DX 500 won't power up

long night

Active Member
Jan 8, 2020
202
37
38
74
Hi to all. I have ta texas star dx 500 that worked fine until recently. I did not push it hard and only drove it with 1 watt. It worked fine and then the last time I turned it on it would no longer power up to transmit. The control lights work, but that is all. Any ideas why it would just quit. I opened it up and no sign of any burnt components. I need to know what to check and how to check it out.
Thank you, Long Night
 

nomadradio

Analog Retentive
Apr 3, 2005
5,664
8,420
573
Louisville, KY
www.nomadradio.com
Keying transistor. It's just to the rear of the relay. Found that a low carrier can cause it to overheat and fail. Learned to put a 10uf capacitor in parallel from collector to emitter on the replacement transistor. This extends the life of the replacement part. Type number is 2N2907A or PN2907. Literally hundreds of other types will also work, but that's the most-generic of all the numbers that will.

73
 

long night

Active Member
Jan 8, 2020
202
37
38
74
Keying transistor. It's just to the rear of the relay. Found that a low carrier can cause it to overheat and fail. Learned to put a 10uf capacitor in parallel from collector to emitter on the replacement transistor. This extends the life of the replacement part. Type number is 2N2907A or PN2907. Literally hundreds of other types will also work, but that's the most-generic of all the numbers that will.

73
Thank you sir for the explanation and help telling me where the transistor is located and how to extend the life of the transistor. I am not very knowledgeable about this amp so you are quite helpful. When you say in parallel would that be attaching on leg of the 10 uf cap to the collector and one leg to the emitter?
Thanks again sir.
 

144inBama

Sr. Member
Apr 22, 2020
618
1,057
153
53
Lower Alabama
When you say in parallel would that be attaching on leg of the 10 uf cap to the collector and one leg to the emitter?
Thanks again sir.

yep, as such.....

Screenshot 2021-09-23 044538.png
 

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