Re: Hi all, newbie with a ?

Jul 02, 2003 1 Replies

Well Dave, You sound like you have a moderate amount of knowledge and I assume that you tried to locate a schematic. Draw the circuit from the pc board traces. Look at the holes where the transistor was and draw a circuit as you follow the traces. Will your "guessed" transistor fit this circuit? Good Luck, Tom



I hope this is the right group for the question I have to post. If not,

let


me know, and I will skeedaddle.
>
> I am trying to repair a 20-year-old Uniden handheld CB transceiver, which
I
*think* has the finals blown. My neighbor picks up no signal when I
> transmit to him from about 50 feet away, but my shortwave radio picks up

the


transmission from only a few feet away. I can't find my wattmeter as most
> of my electronic stuff is still packed and in storage (we recently had to
> abandon house for two months.) I do have my oscilloscope and DMM, plus a
> few other odds and ends that never got packed. I *think* I have located

the


transistor that acts as the final amplifier and have removed it from the
> circuit. It is a TO220 style, and the only markings on it are "2029C/1".
> Am I safe in assuming that this is basically a 2SC2029, or some other
> compatible? My only clues to the identity of this puppy are its physical
> location on the board (near the antenna connection) and the fact that it

is


surrounded by several small (3/16" x 5/16") coils. I do*not* want to just
> stick another transistor in there in its place and try to transmit, but I

am


not sure of where to start with my analysis (it's been a long time since
> I've done anything quite like this.) Oh, one more thing, this CB has a
> seven-inch long alluminum heatsink running the length of the PC board, and
> this transistor and one IC (at the other end) are the only things on it

(in


other words, there are no other power transistors in the circuit).
>
> Should I proceed with a 2SC2029 or an equivelant? What do others think?
I
value your opinions, and any help would be appreciated.
>
> Thanks,
>
> Dave
> snipped-for-privacy@hotmail.com
>
>
>
>
>

Hello Tom,

Thanks for the reply. Yes, I tried to find a Sams Photofact on this guy, but they don't seem to do much with Uniden products. From what I can tell the transistor that the local parts distributer recommended should fit nicely. It is a 5W final RF output NPN transistor, TO220 style, and the voltage parameters ought to work (I think). They had two and I bought them both. Put one in and tried it out with my neighbor listening on his unit. He said I came through loud and clear. Then I tried to hook it up to my watttmeter and it only regisered about 150 mW. SWR's were HIGH. Suspecting I blew the new transistor I pulled it out and replaced it with the second spare. Will probably not mess with it much more if it seems to work again. Or i may take it to the local shop just down I-10 and ask them to check it out for me to see if it's putting out a decent signal. I still can't seem to get any response to a radio check, but that might be due to my location, don't know. Oh well, It never worked anyway.

Take it easy...

Dave snipped-for-privacy@hotmail.com

you

which

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a

"2029C/1".

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just

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