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Tech808
Moderator
Username: Tech808

Post Number: 8013
Registered: 8-2002


Posted on Sunday, October 30, 2005 - 11:33 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

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Freebird
Intermediate Member
Username: Freebird

Post Number: 287
Registered: 1-2003


Posted on Sunday, October 30, 2005 - 10:35 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I was reading if i clip R 131 on my cobra 2000 this will make my audio louder but where the heck is R 131 i can't seem to find it.
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Kid_vicious
Advanced Member
Username: Kid_vicious

Post Number: 761
Registered: 9-2004
Posted on Sunday, October 30, 2005 - 11:34 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

yes, im sure it has been done before.

i dont quite understand, but OK.
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Freebird
Intermediate Member
Username: Freebird

Post Number: 288
Registered: 1-2003


Posted on Monday, October 31, 2005 - 5:56 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

you dont understand?LOL what im asking is where is R 131 on the circut board of the cobra 2000 i can't seem to find it.
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Kid_vicious
Advanced Member
Username: Kid_vicious

Post Number: 766
Registered: 9-2004
Posted on Tuesday, November 01, 2005 - 12:00 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

freebird, when i posted that, your post wasnt there. just a blank post by tech808. i understand why my little joke seemed confusing.

now for some help:

position your 2000gtl so that it is facing you and right side up with both top covers off.

look near the front right hand side of the PC board near L2.
R131 is right in front of L2 beside TR26 (or Q26 depending on which model you have)
i would say it's about two inches in from the right side and three inches back from the front of the PC board.

clipping R131 is about the most drastic way of increasing modulation in these radios. if you run a power mic, you're gonna sound distorted, and some people will tell you you're loud and proud, and some will tell you you sound like KA KA.
if you do this, first remember to solder very carefully as this is one heck of a classic radio, and worth a lot of money on the used market, just not if they're thrashed on the inside.
and you should run the dynamike control at about 12 o'clock.

how much are you looking to mod this radio?
how much experience do you have in doing this type of work?
the reason i ask is because i have a bunch of tried and true mods for this radio, and i'll post them if you're interested.
you can find them now in a thread titled, "my 2000gtl"
have fun,
matt
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Freebird
Intermediate Member
Username: Freebird

Post Number: 290
Registered: 1-2003


Posted on Wednesday, November 02, 2005 - 2:26 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

ok matt well the radio has extra channels and an unlocked clarifier i turned up the wattage etc i have the mods for that but the audio was never clipped.what other mods is there?anyway thanks for the help ill try to find r 131 later today.Oh and i work on radios all the time im really kinda good at it.thanks
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Airplane1
Advanced Member
Username: Airplane1

Post Number: 618
Registered: 5-2004


Posted on Wednesday, November 02, 2005 - 7:22 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Kid_Vivious,
Post them for me. I am interrested in them.

thanks,
AP
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Kid_vicious
Advanced Member
Username: Kid_vicious

Post Number: 780
Registered: 9-2004
Posted on Thursday, November 03, 2005 - 11:24 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

you got it airplane1!

since i said in other posts that i would; im listing the mods that i have done to my radio.
i have tried others, but these are the keepers.
i did the npc mod and volted the final, but i did not remove TR24. instead i added 1.5K to the middle leg.
remove C207
replace R206 with a 39K resistor.
remove C232
change R114 to 10K resistor.
change C18 to 680uF 16 volt or higher
change C172 to 2200uF 35 volt or higher
replace R180 with a jumper
replace TR41 with NTE152
replace C163 with 3pF
remove R131 and put on a switch. (this is mostly for DX use, as it will cause some distortion at close distances. i have only flipped the switch once to make a rare contact on AM with San Francisco.)

for the receiver, replace TR14 with a 2sc2999 or NTE 107.
replace TR19 with the old TR14. (2sc1674)
replace D1, D2, D21, D22 with NTE583 diodes.

replace all 10 volt rated electrolytic caps with 16 volt types. (i replaced ALL the electrolytic caps in mine as it is an old radio.)

i cannot take credit for finding these mods on my own. a very smart man on this site by the name of patzerozero posted them for me, and i did pretty much the same mods he had done.
this radio works great like this.

hope this helps, if you do nothing else; do the TR 14 and the TR41 swaps.
matt

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