direct injection on a Cobra 29 LX

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direct injection on a Cobra 29 LX

Postby WEAKEST STATION » Mon Aug 01, 2016 10:34 am

Direct injection on a Cobra 29 LX where would be the injection point on I know it's after the audio amplifier but where exactly would that be does anyone know yeah and I'm new to this form so hi everyone they call me the weakest station in the nation out of Vermont
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Re: direct injection on a Cobra 29 LX

Postby Goldfinger » Wed Aug 03, 2016 10:36 am

You would inject through a 2.2uF or larger cap to the right hand hole (looking from the top) of C37 where it junctions with R48.
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Re: direct injection on a Cobra 29 LX

Postby WEAKEST STATION » Thu Aug 04, 2016 2:46 pm

hey thanks man maybe I'll give it a try
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Re: direct injection on a Cobra 29 LX

Postby Goldfinger » Thu Aug 04, 2016 3:15 pm

Red X

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Re: direct injection on a Cobra 29 LX

Postby WEAKEST STATION » Fri Aug 05, 2016 6:58 pm

P ut the audio through c-37 installed a quarter-inch Jack for thE gear on the back of the set I'm getting feedback through the radio when it's not key I guess if I did something not quite right it's like it's got talk back when you don't Key otherwise I'm at it's working good unfortunately for me I know enough just to be dangerous 73 S the weakest station in the nation I would appreciate some feedback from someone cuz I got Plenti
for my radio haha :lol:
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Re: direct injection on a Cobra 29 LX

Postby Goldfinger » Sat Aug 06, 2016 4:41 pm

It's just the design of the radio. Any radio with an audio transformer uses the same audio section for both the transmit and receive. Cobra 2000's or Ranger/Galaxy have a separate modulator for transmit which makes them easier to inject. You might have to re-install C37 making it higher in value and inject at the right hand hole of C68 instead. You will lose a little fidelity but you wont have the feedback problem.
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Re: direct injection on a Cobra 29 LX

Postby WEAKEST STATION » Sat Aug 13, 2016 7:37 pm

man it sounded so good nice and smooth soft audio I definitely don't want to lose any of my High Fidelity at all I'll probably figure something relay for when I'm receiving and thanks again for all the information you've been a great big hand Man probably a few more adjustments I've got it for it's hardly squealing now thanks again for the information you've been a big hand
thanks again from the weakest station in the nation :D
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Re: direct injection on a Cobra 29 LX

Postby 479tx » Sun Aug 14, 2016 8:41 pm

GoldFinger is the man, that is for sure. Post a gate of the direct injected 29 audio if you get a chance weak station, I'd love to hear it.
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Re: direct injection on a Cobra 29 LX

Postby 221 » Wed Feb 15, 2017 5:50 am

Looking at the top of the radio would be the solder side of the radio is that correct the photo here shows the bottom side of the radio which is the component side I am confused. So with the component side up it would be in the right.hole of c37 is that correct
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Re: direct injection on a Cobra 29 LX

Postby 221 » Wed Feb 15, 2017 5:52 am

Also what are the cap mods for this radio is it the same as the cobra 29 classic
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Re: direct injection on a Cobra 29 LX

Postby 221 » Wed Feb 15, 2017 5:22 pm

Can anyone help me here I found info on the cobra 29 LX but it doesn't have all the info I need
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Re: direct injection on a Cobra 29 LX

Postby Goldfinger » Wed Feb 15, 2017 9:40 pm

221:
To inject a 29LX..

Change C37 to a .1uF, (104) green mylar
Remove C68 (if C68 is a .1 (104), use for C37)
Inject through a 2.2uF to the right hand hole (from the top parts side) of C68
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Re: direct injection on a Cobra 29 LX

Postby Goldfinger » Wed Feb 15, 2017 10:04 pm

221 wrote:Also what are the cap mods for this radio is it the same as the cobra 29 classic


Yes, the receive is the same as the LTD. (C33 and C40)
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Re: direct injection on a Cobra 29 LX

Postby 221 » Thu Feb 16, 2017 5:54 am

OK thanks alot that answers all my questions on the cobra 29 LX.
How about the cobra 2000 what can I use for an audio amp. I am using a behringer 802 EQ from what I understand that isn't enough to push the radio. I don't know what to buy so many different types of audio amps .
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Re: direct injection on a Cobra 29 LX

Postby 221 » Wed Feb 22, 2017 12:11 pm

Are the cap mods supposed to make the audio much better on the transmit part. I am not worried about the highs and lows changing I can do that with the eq. I am just trying to see what is the purpose of the cap mods.
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Re: direct injection on a Cobra 29 LX

Postby Goldfinger » Wed Feb 22, 2017 6:27 pm

When injecting at C68 you must make C37 higher in value to be able to pass frequencies below 300hz
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Re: direct injection on a Cobra 29 LX

Postby 221 » Thu Feb 23, 2017 12:33 pm

I could not get it to work at c68 I had to inject it at c37 I tried it at c68 but it was muffled as crap so I did it at c37 but I didn't change any cap just removed c37 all together don't know if this was right or not. All the info I seen said c37 so I don't know but it says inject it at c37 it didn't say remove it but I had to remove it it would not work with c37 still In the radio
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Re: direct injection on a Cobra 29 LX

Postby 221 » Thu Feb 23, 2017 12:35 pm

I must be getting things confused or something because I have done it through c 37 and I get terrible feedback on recieve and on c68 it was muffled as crap so what am I doing wrong here. Both I injected it at the right hand hole and when doing this is the cap SUPPOSED TO be removed completely at c 68 or c37
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Re: direct injection on a Cobra 29 LX

Postby 221 » Thu Feb 23, 2017 2:51 pm

At the beginning of the post it says inject at c37 and r48 but you say c68 so I am confused on what is right
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Re: direct injection on a Cobra 29 LX

Postby 221 » Fri Feb 24, 2017 11:06 am

SORRY I AM NOT TRYING TO BE A PAIN BUT I JUST WANT TO MAKE SURE IT IS DONE RIGHT SO IS IT BEST TO GO TO C68 or C37
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Re: direct injection on a Cobra 29 LX

Postby Goldfinger » Fri Feb 24, 2017 12:35 pm

Yes, when injecting, remove the factory cap at the injection point and add your own cap in series with the positive wire coming from the jack you installed on the radio and connect to the right hand hole (looking from the top).
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Re: direct injection on a Cobra 29 LX

Postby 221 » Fri Feb 24, 2017 2:33 pm

Thanks but am I supposed to inject at c68 or C37 which is the best place to inject the audio
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Re: direct injection on a Cobra 29 LX

Postby a365 » Fri Feb 24, 2017 10:13 pm

Hi:

If you read carefully Goldfinger suggest to replace C37 with a 104 Mylar Type Capacitor or .1uF Non-Polarized Electrolytic

Inject audio @ C68

If C68 is a green Mylar stock and you replace it with a Tantalum, make sure the Tantalum's + Terminal goes towards the Base of TR 17 and the - Terminal just to your Audio Injection Cable

The - Terminal of the New Capacitor does not connect back to the PC Board

Use a 1uF/25V Tantalum

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Re: direct injection on a Cobra 29 LX

Postby redlght » Wed Aug 23, 2017 12:49 pm

Which rx tx audio mod works with a 29LX? thanks
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Re: direct injection on a Cobra 29 LX

Postby Goldfinger » Tue Aug 29, 2017 10:09 am

If you just want it hi-fi through the mic jack, the 29LTD mod on the forum is the ticket.
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Re: direct injection on a Cobra 29 LX

Postby redlght » Tue Aug 29, 2017 12:04 pm

Thanks again and ~BE well~

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