Cobra 25 & 2SC1969 final Question

[Smokn_X2]

I installed the 1969 unit into a cobra 25 today and when I key the mic the meter goes backwards, This is a new model 25 with the night watch.
I have done this before with a Cobra 29 and everything came out great, So I thought I would try it on the 25. Is there a fairly simple way for me to keep it in there, or should I put the stock final back in?
Thanks for any answers

 

[King Mudduck]

I installed the 1969 unit into a cobra 25 today and when I key the mic the meter goes backwards, This is a new model 25 with the night watch.
I have done this before with a Cobra 29 and everything came out great, So I thought I would try it on the 25. Is there a fairly simple way for me to keep it in there, or should I put the stock final back in?
Thanks for any answers

Are you sure the 1969 is good?

 

[Smokn_X2]

Are you sure the 1969 is good?

Man, I don't know. I have 5 brand new 1969 finals, I guess I could try another one but I wanted to sell them later on when there all gone from wholesale. Would it be possible to have shot a current through the 1969 when I installed it? Do they sometimes come bad, brand new like that? I guess it could be a possibility...
I went to put the stock final back in and now I can't find it.:headbang I'm having a time here because there are two finals that could be the stock one, there is the 2sc2078 made by Sanyo, an there is the 2sc2078e made by Panasonic. The 2078e is about $8 where the plain 2078 is 65 cent, I don't know which one is right and I want to be sure before I order it, or I can try another 1969. What would you do in my shoes? Thanks...

 

[Smokn_X2]

I found my problem; All the new Cobra radios have changed over from Uniden parts, to a cheaper part using 1/4 watt resistors whereas Uniden used 1/2 watt resistors. Therefor making new Cobra radios incompatible with the 2SC1969 Transistor.

I guess I wont be getting any more Cobra's...

 

[Moleculo]

No, that's not it...it should work fine. I've done this mod on a bunch of brand new Cobra 29's and it always works. The 25 is very similar. What else did you change when you changed the final?

BTW, if you don't want those 1969's, you can send them to me

 

[Smokn_X2]

No, that's not it...it should work fine. I've done this mod on a bunch of brand new Cobra 29's and it always works. The 25 is very similar. What else did you change when you changed the final?

BTW, if you don't want those 1969's, you can send them to me

I've done the mod to 29's and one 97 model 25 and had no trouble.
I didn't change anything, just the final.
After that I had planned on changing a few others around but I didn't get that far. You should be able to run a 1969 in a stock Cobra 29/25, I don't know why this one wont.

 

[Moleculo]

Try doing a TX alignment after you install the final.

 

[Smokn_X2]

Try doing a TX alignment after you install the final.

Are their two different 2sc1969 transistors, because these are the same size as the mosfet finals and I'm pretty sure the 1969 is slightly smaller and not as shiny.

 

[Moleculo]

There are several different packages...toshiba, mitsubishi, some others that I don't remember off the top of my head, but they all should perform the same.

 

[Bionic Chicken]

There was a bad bunch of 1969's being sold a while back. I don't remember them having the Mitsubishi logo on them but they would not work. I know a lot of them came from a business in Kentucky.
The difference in the wattage of resistors will not have an impact on the output of the radio..........only the current handling capability of them. Like suggested in a previous post try to realign the transmitter and see if that helps.

 

[tdill49]

Does it move backward as soon as you key-up or does it backwards modulate?

 

[Robb]

I could be mistaken, but I think that if it is backward modulating - because it is getting too much bias current to the final. You might have to check it and see; that is what I would do.

I think that replacing the driver would certainly help the output as well. As it is similar to the Cobra 29 in that respect.

Mole; what do you think?

 

[Moleculo]

Not seeing what it's doing personally, it's hard to say, but he needs to check everything. He needs to check the bias current, the transmit alignmnet and also look to see if someone volted it. If all that is good, then he's probably got a bad final and/or driver.