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Cobra 29 w/Powermod

Discussion in 'CB and Export Equipment and Accessories' started by Mudbug101, Oct 19, 2005.

  1. Mudbug101

    Mudbug101 Guest

    I ordered a powermod off eBay and just got done installing it. I consisted of a peak and tune setup, I guess. I did exactly what the instructions said, now my SWR Cal does not work good. The knob goes all the way to the right to make it Calibrate to about 2.5 or 3 on the meter. I am not really concerned about that though; my SWR is still 1:1. Does anyone have any specs on what my wattage is here. I am just curious on how much I am putting out. Maybe dead key, swing and modulation.

    Here is what I bought:
    http://cgi.ebay.com/Cobra-CB-25-29-...802786265QQcategoryZ40055QQrdZ1QQcmdZViewItem

    Thanks


     
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  2. buckwhite

    buckwhite Member

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    the reason the needle doesnt peg out is because your dead key is lowered. the only way to find out is to put it on a meter. personally i do variable power in the radios i tune, you dont need but a couple parts and you can vary dead key to whatever you want...
     
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  3. Mudbug101

    Mudbug101 Guest

    What do you think it is producing out on dead key? Maybe 3 watts? What about swing? I am just wanting an estimate on what it is producing. If I turn the SWR cal, is that adjusting my dead key? What does the swr cal do now?
     
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  4. buckwhite

    buckwhite Member

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    no way to tell what its keying without a meter, but since the swr cal wont peg i would say 1-2 watts at the most, swinging anywhere from 15-25 watts depending on if anything else has been done to the radio. the swr cal is doing just what it says.
     
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  5. Mudbug101

    Mudbug101 Guest

    Ok, let's relate that to distance. If I am dead keying at let's say 2 watts and swinging at 25 watts, how much better is this then a stock? How far can I go on average (distance)?
     
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  6. pinejuice

    pinejuice Member

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    you really cant tell you will probly get 10 miles or so..just depends on your antenna setup you can get more.base and mobile varys on how far you would be heard.key it and find out ;)
     
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  7. DTB Radio

    DTB Radio Active Member

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    You will likely find that, compared to a proper peak and tune, the radio will NOT have the range it could have. You will basically be blaringly loud at close range, but you will drop out as the range opens.
     
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  8. Mudbug101

    Mudbug101 Guest

    That is precisely what is happening, I believe. I talk to some guys and they say that it sounds good and others don't respond at all. I may have to check it with a buddy of mine to see how far we can go and what it sounds like.
     
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  9. Butcher318

    Butcher318 Active Member

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    For the most part these kits on Rip-Bay are a waste of time unless you have a qualified tech install them. It's not just a matter of following their oversimplified installation directions.
    The best part of that " kit " is the 1969 final. You have about 6 bucks in parts there. your best bet now is to have a tech do a peak and tune on that radio and see what he can get. For a more detailed view someone like DTB Radio could look at those parts and tell you exactly what you bought and what can be done.
     
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  10. Switch Kit

    Switch Kit Active Member

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    You didn't get a bad deal on your little kit there 101 .....No meter huh ? .....that makes it kind of tough dude )-: Just looks like a swing kit to me with the added stronger final is all ....there's still more to it then just installing it .....I totally give you props on what you have done so far !! ...mans got to start somewhere. My guess is this ....Your not running a amplifier and that's basically what a cap/resistor mods are all about .....low dK high swing .....to be honest with you ...your 29 would have tuned around 5 to 6 with a 20 to 24 watt swing with a 100% modulation by itself ......No meter huh ? Wow !! .....I bet one of those caps went were the jumper was in front of the final ? .....You can do this.....follow the wires from the rf gain control to the board .....un-solder them and put a jumper on the bottom of the board from the two points you pulled the wires out at (this will leave your rf gain wide open) then you can take the wires from the rf-gain control to the two points on the board where you put in the cap in the jumpers place in front of the final on the bottom of the board (one wire to each leg of the cap) ......now you will have a variable drive (-: .....but man !!! You have got to have somekind of meter to do this stuff !! ........You got some balls dude for sure !!! .....IM on your side....whatever you decide to do ....Good luck man !!
     
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  11. Mitsurugi

    Mitsurugi Guest

    Is your resistor de-marked like the one
    in the picture they posted on the Ebay listing?
    [​IMG]
     
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  12. Mudbug101

    Mudbug101 Guest

    No, it isn't. It is one that has a yellow, grey, and blue band. Does this make a difference?
     
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  13. Mudbug101

    Mudbug101 Guest

    Alright, I just tested my range on this thing and I am not impressed. I can go about 1.5 miles on this mod where at normally, I could go about 10 miles. Hum, this makes me think. Could I take these out and put the originals back in or did I do something wrong? I still got the old pieces, maybe I will put the old back in and possibly leave the swing kit in there. Would this work? What's my problem?
     
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  14. nomadradio

    nomadradio Active Member

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    Hi MB,
    Now that you have proven to yourself that this trick is no real advantage to your "barefoot" transmitting range, let's get down to the real reason it's popular.

    Reducing the radio's carrier power is only desirable if you use an external "linear" amplifier. An amplifier has the bad habit of exaggerating your carrier (dead-key) power, and reducing the so-called 'forward swing', or modulated part of your AM transmit signal. Tends to reduce the audio level that comes out of the speaker on the other end.

    Reducing the radio's carrier power below the normal proportion serves to compensate for this quirk. If done, right at least. It's a strategy that improves the amplifier's performance, but offers NOTHING at all if you use the radio by itself, or "barefoot", as they say.

    Now that you've convinced yourself, I don't need to try.

    Best advice I can offer is to remove the resistor and capacitor that went in place of the wire jumper.

    Put the wire jumper back, or a new wire in its place.

    Odds are this will give you all the radio has to offer on transmit, without changing anything else. Unless they also had you remove or jump around the black plastic rectifier across the circuit board from the final transistor. That jumper should come back off, if this was done. If they told you to pull the diode, put it back. Not the tiny glass one, the larger black epoxy plastic one. Hmmmmm. Now that's a web page somebody (else) should put up. "How to remove the Bling Mod from your Cobra 29/ Uniden PC76/78."

    The radio will now show between 5 and 6 Watts of carrier power. Too much to use with most amplifiers, but perfectly legit for running barefoot. And louder to boot, for anyone out there in the distance. Another radio across the parking lot may not show you a big difference that you can tell.

    Nothing quite like doing the before-and-after comparison yourself. Makes the result easier to believe, ususally.

    73
     
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  15. Mitsurugi

    Mitsurugi Guest

    Your advice, although well meaning is no more helpful then what
    he has now. There are ways to tune a barefoot radio and
    to tune to run an amp.

    Variable power is the only way to go for an amp, a resistor
    will just not cut it. It is impossible to tell someone what
    resistor will do what, with so many other variables.

    Barefoot? make carrier 1/2 of the average max
    or 1/4 of the peak max. mods are everywhere.
     
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