| Author |
Message |
    
Mayor513
Intermediate Member
Username: Mayor513
Post Number: 117
Registered: 3-2002
| | Posted on Wednesday, August 02, 2006 - 6:05 pm: | 
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--Hi, all. I have been getting in some older model President radios (I love President, haha) and I was wondering if there were some higher rated final transistors I could put in these radios? Preferably, I would like something that is not only a physical/mechanical drop-in replacement, but also an electrical drop-in replacement.
--For instance, the radios I am talking about is a President AR44, which is supposed to have the same guts as the Cobra 25...the final transistor in it is the 2SC2075. The other radio is a President Honest Abe, which is supposed to be the same thing as the old Cobra 29XLR (UPD858PLL, yay!!). I don't know what the final transistor is in the President Honest Abe, because it hasn't been shipped out to me, yet. However, I looked at the schematics for the 29XLR, and I see three transistors listed that might be the final. They are 2SC2091, 2SC2092, and 2SC2076. I am thinking that the 2076 is the final, but I am not sure.
--So, can anyone tell me if there is an easy to install, higher power rated, mechanical and electrical drop-in for the above finals? Perhaps 1969 or 2312, anything? If not, that's okay, I just thought it might be a fun little project. Thanks for your help. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1939
Registered: 9-2004
| | Posted on Wednesday, August 02, 2006 - 9:45 pm: |
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the 2SC2075 can be replaced with a 2SC1969, and it should work fine.
sometimes a resistor or two must be changed to get the bias right.
only one way to find out!
the 2SC2076 is an audio amp, not the final.
the 2SC2092 is the final, and can also be replaced with the 2SC1969. same deal as above.
remember to rebias the driver and final after replacing the final.
dont expect too much of a wattage increase, but good luck anyway,
matt |
Hotwire
Senior Member
Username: Hotwire
Post Number: 1615
Registered: 1-2005
| | Posted on Thursday, August 03, 2006 - 1:19 pm: |
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The increase will not even be noticed in the range you'll get. Unless your just doing it for the fun of working on radios I would just use an amp.73
CEF491 |
Mayor513
Intermediate Member
Username: Mayor513
Post Number: 118
Registered: 3-2002
| | Posted on Thursday, August 03, 2006 - 4:15 pm: |
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--Yeah, I just mainly want to do it to have the higher rated final in there (I think the 1969 is rated almost double?). If the SWR rises in the automobile (you never know, with all the jarring the antenna takes), the radio should be able to handle the mismatch a little better, too. If I do need the extra range, I will install the Texas Star 350 I got from Copper Electronics. Thanks. |
Znut
Advanced Member
Username: Znut
Post Number: 716
Registered: 1-2002
| | Posted on Thursday, August 10, 2006 - 7:37 pm: |
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What about the ERF2030? |
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