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Benjamin Gross
Posted on Tuesday, May 22, 2001 - 12:54 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

How do you hook up talk back on a uniden pc 122?
also how do you fix a problem with the static not coming in when squelch is all the way down? If you tap on the radio it comes back. The speaker lead are all good
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307 (307)
Posted on Tuesday, May 22, 2001 - 6:17 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Put a 15 to 50 ohm resistor on the main board connecting the Speaker Output jack (center) to chassis ground. As for the noise , sounds like a loose solder joint , unfortunatly it could be anywhere.
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onwatchman
Posted on Wednesday, May 23, 2001 - 4:11 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

hey can you tell me how to install talk back on the navajo trc 432? Not feed back like some c.b. hackers do but tried and true talkback?! Thanx "307" for the help it is always appreciated sincerly "watchman555" Tn..
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307 (307)
Posted on Wednesday, May 23, 2001 - 8:25 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I will take a good guess as to what you need. Instead of using a resistor on the speaker jack to chassis , Try a non-polorized 220 Uf capacitor from the hot side of the speaker to chassis ground , NOT case ground. I don't show a TRC-432 in Sams books however it rings a bell...
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Benjamin Gross
Posted on Thursday, May 24, 2001 - 1:44 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

307(307) what do you mean by speaker output jack (center) Also by chassis ground you mean the ground that the radio is connected to on the car.is the message that you that you wrote on the 23 apply to me?
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307 (307)
Posted on Thursday, May 24, 2001 - 7:41 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

1)The Speaker output jack is the place in the rear of the radio that you plug in an external speaker. There are three connections on it. Use the center pin. You can see it on the solder side of the main board right at the jack.

2) Chassis ground is the circuit board inside the radio and not the case ground.
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Dennis Morgan
Posted on Saturday, May 26, 2001 - 9:41 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Chassis ground? Frame Ground? Car Ground? Are you saying these grounds are electrically isolated from each other?
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307 (307)
Posted on Sunday, May 27, 2001 - 12:59 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Yes , Chassis Ground (radio) is isolated from Frame Ground.
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billy bob
Posted on Sunday, June 10, 2001 - 11:39 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

where is the proper place to wire up a connex board in a cobra 148gtl, before the mike gain (at the mike input block on the pink wire) or between the mike gain and the cb main board
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307 (307)
Posted on Sunday, June 10, 2001 - 3:59 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

AFTER the mic gain. This is the best place to do it because if you do it before the mic gain , the clarity will drop when it is turned down.
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Anonymous
Posted on Wednesday, August 22, 2001 - 8:20 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I saw somewhere there was a mod for talkback for the 2950dx any one know it?
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Tech181 (Tech181)
Posted on Thursday, August 23, 2001 - 12:07 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Anonymous,

Here's your mod.

Turn the radio with the speaker side up, with the display facing you. You will need to locate D-78. In the upper right area of the board you'll see IC-14. You'll also see T-1 to the left of IC-14. D-78 is toward the front of near T-1.

Cut D-78. Wire a SPST switch in series with D-78 to make it switchable so you can turn talk-back on and off. Then replace D-115 with a .0047uF disc capacitor.

Steve
Tech181
Tech181@copperelectronics.com
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dead 2950
Posted on Thursday, August 23, 2001 - 3:25 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Will the above 2950 DX talkback work on an older 2950?
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bluedog
Posted on Friday, August 24, 2001 - 10:46 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

On alot of the radios i have found that the best place to get talkback is at the mic socket and all u need is a 100k resistor and solder it to the mic modulation pin on the mic socket and to board ground. It gives a little bit clearer talkback and i would suggest putting a 50k varable pot on it to have variable talkback.
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Anonymous
Posted on Sunday, August 26, 2001 - 6:47 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Are you sure that is a 2950dx i don't even see an ic 14 in there?
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Tech181 (Tech181)
Posted on Monday, August 27, 2001 - 12:07 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Anonymous,

I believe this is an old mod, may not work on the newer rigs.

Steve
Tech181
Tech181@copperelectronics.com
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Anonymous
Posted on Wednesday, August 29, 2001 - 7:10 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Ok i was trying to figure that one out. My sight is bad and I just couldn't find any of the diodes mentioned in my 2950dx even with the reference points. I'm glad to find out that the mod is for a old version!
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Anonymous
Posted on Sunday, September 02, 2001 - 11:49 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

THIS IS FROM THE RCI WEB PAGE: Do you know that you can add talk back to the new DX models of the RCI-2950, 2970 by simply by lifting one end of D67 from the circuit and tape the end to prevent it from shorting out against metal or some other component. With this feature, operators can try different microphones out and hear what they will sound like in actual use. You can even wire in a SPST switch so that you can turn it on & off when desired.
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Badintermod
Posted on Sunday, September 02, 2001 - 2:28 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I am looking for instructions for adding talkback to my Magnum 257
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Anonymous
Posted on Sunday, September 02, 2001 - 2:55 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Well,I put talkback on my Uniden PC-68xl.I used a
180ohm resistor and it clears it up a good bit and doesn't allow for feedback.It may be different on other radios.Just thought I tell ya what works for me.

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