Copper Talk » Open Forum » Archived Messages » 2002 » Archived Messages 07/01/2002 to 07/31/2002 » Realistic trc-490 « Previous Next »

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chris leggett
Posted on Sunday, June 30, 2002 - 8:54 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I have one.Had it about 20 years.Does anybody know of any channel mods?

So far I've only found 27.445 if I hold the channel 9 switch 1/2 way in.
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Snapperhead
Posted on Sunday, June 30, 2002 - 11:11 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Hey Chris, What chip do ya got MB8719 or the MB8734?????
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chris leggett
Posted on Monday, July 01, 2002 - 12:31 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Chip????heck I dunno.Where is it? whats it look like?My dad bought the thing new,cover has never been off!

I took it in to my local radio shop/limiter clipper because the lsb is off freq once it warms up and the guy told me to take it back out,he wouldn't even touch it.

I figured that while they was in there I could get some freqs added......looks like I'll be learnin a new trade soon! :D

Pardon my dumbness as I'm technically challenged.
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Hoosier Cardinal
Posted on Monday, July 01, 2002 - 1:22 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

If thats a 490 then it has the 8719 PLL chip. Those are good chips if you want some "extras" in your rig. Im sure you will find someone to do the mods for you if you dont want to do it yourself.. LOL I know of one shop that charges 200.00 to do a simple channel mod!! Some guys will do it and some will do it but it will cost you then there are some that absolutely WILL NOT touch a radio that has the "channels"!!!
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Snapperhead
Posted on Monday, July 01, 2002 - 6:59 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Sorry Chris, I was looking in some of my old Lou Franklin books for that radio. The book I have identifies radios buy there chip....Didn't mean to make you feel dumb or anything. We better leave this one for one of the fine techs here..
goodluck...........
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Tech181
Posted on Monday, July 01, 2002 - 12:23 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Chris,

If this radio has the MB8719 chip it's very easy to modify. Pretty much the same as the Cobra 2000.

1) Cut the trace on the board coming off PIN 10 of the chip so it is no longer connected to board ground as it was originally. Do this with an Exacto knife or other such implement.

(PIN 10) -> === (cut) === (ground)

2) Solder one leg of a SPST toggle switch to PIN 10 on the chip and the other leg to the isolated ground (the trace on the other side of the cut you made). This is board ground!

3) Solder one leg of ANOTHER SPST toggle to PIN 12 of the chip and the other leg of the same switch to PIN 11.

Looking at the bottom of the circuit board PIN 1 is the first pin to the top of the indentation on the one end of the chip. PIN 10 is on the bottom of the opposite corner, PIN 11 is next going to the left, then 12, etc.

Steve
Tech181
Tech181@copperelectronics.com