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Message |
    
Scannersam
New member
Username: Scannersam
Post Number: 6
Registered: 6-2002
| | Posted on Tuesday, December 20, 2005 - 6:17 pm: | 
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Is there anyone out on the FORUME that knows of any mods and or tune up stuff for the Cobra 29 NW ST? I just got this and it seems to only be doing about 3 watts out put and about 65%----70%
modulation sith a stock mic.I would like to get a tad bit more out of it if I can and boost the receive if anyone knows. Thank you for any help.
SCANNERSAM |
Wildrat
Advanced Member
Username: Wildrat
Post Number: 524
Registered: 12-2003
| | Posted on Tuesday, December 20, 2005 - 7:55 pm: |
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You could look at the mod list under tools on the left side of the page. There all kinds of web sites out there with mods for the 29 also, just do a Google search. Kid Vicious will probably roll in here sometime and he will probably be able to tell you something also, and there are many others that will help you.
Wildrat |
Scannersam
New member
Username: Scannersam
Post Number: 7
Registered: 6-2002
| | Posted on Tuesday, December 20, 2005 - 8:34 pm: |
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Thank you. I did go to a few sites but they really did not say much. Got a great forum here. Thanks SAM |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 945
Registered: 9-2004
| | Posted on Thursday, December 22, 2005 - 5:44 pm: |
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thanks for the vote of confidence wildrat!
you can turn up VR 4 for more modulation.
or you can remove D11. if you remove D11, you may hve to keep the mic gain on the front panel at 12o'clock if you use a power mic.
the TX coils are L14,13,12.
tune these while saying, "ahhhhhh" into the mic for max. PEP reading on wattmeter or radios S-meter.
ill find more at home and post tomorrow.
matt |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 952
Registered: 9-2004
| | Posted on Monday, December 26, 2005 - 12:28 am: |
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ok here is the rest of the stuff on the 29ltd (the one you have is the same)
some of this stuff, i dont like to do, but its up to you. (i never spread the coils)
Receive Boost: Locate pin 14 of the PLL chip, and the Positive (+) side of C-12. Install a 22k-220k ohm resistor between these two points. The smaller the value, the more the receive is boosted. Use CARE when soldering to the PLL chip! If desired, this mod may be wired through a switch.
Supertune: Replace the stock final with a 2SC1969 unit. Solder a jumper across D8 (this may cause receive distortion at high volumes, remove jumper if it does). Solder a 68pf cap across C62. Solder a 68pf cap across C59 if there is already a 33pf across it. If there isn't, use 100pf instead. Replace R 55 with a 10-15k resistor, and solder a 33-55 pf cap across that resistor. Replace R58 with a 4.7 ohm resistor. Set VR4 just a bit to the right of half-way open. If D11 or C3 have been removed, replace them. D11 is a simple small-signal swithcing diode like a 1n147, and C3 is just a 1uf electrolytic. If TR18 has been removed or cut, replace with a 2SA733. Spread Open L12 a tiny bit, and adjust L16 for best swing, using a loud, steady "aaaaaaah" sound into the mic (or if you have a function generator, set it up for 1khz at about 16mv output, and use that. MAKE SURE to use heat-sink compound (a very light coating is sufficient) when mounting the new final, and MAKE SURE the final mount screw is tight!
Channel 9 switch to Channel 19: Cut D32. Hard, huh?
hope this helps,
matt |
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