Recieve mod

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Recieve mod

Postby 221 » Fri Mar 03, 2017 6:45 pm

Is there a mod I can do on a cobra 29 LX for the recieve to be louder like a pre amp. I seen a video on YouTube that gatekeeper did where he did this to a cobra 29 and he put it on a switch. It worked great because when he turned it on it made the people real loud but it didn't make the static louder . Most preamps amplifi the static noise but the one he did didn't it just made the voice louder but he didn't say how it was done.
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Re: Recieve mod

Postby 221 » Wed Mar 08, 2017 4:56 pm

Can anyone answer this question for me
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Re: Recieve mod

Postby Goldfinger » Wed Mar 08, 2017 7:39 pm

Never seen the mod.
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Re: Recieve mod

Postby 31 » Fri Mar 10, 2017 8:24 pm

Yes there is, I need a few to find it, brb
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Re: Recieve mod

Postby 31 » Fri Mar 10, 2017 8:34 pm

Receive Boost: Locate pin 14 of the PLL chip, and the Positive (+) side of C-12. Install a 22k-220k ohm resistor between these two points. The smaller the value, the more the receive is boosted. Use CARE when soldering to the PLL chip! If desired, this mod may be wired through a switch.

From many sites. I did it a long time ago and didn't care for it. Try it out . Not so much a HIfi mod but it does increase the perception of the receive. If you have half an S unit of noise , this mod could raise it to 3 S units of noise. It will not bring out a signal from below the noise, just increase the strength .
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Re: Recieve mod

Postby 221 » Sat Mar 11, 2017 8:44 am

Thanks alot for the info I seen the mod on YouTube a guy called gate keeper and I don't know how or what he done but it didn't increase the static but did increase the other stations audio. The bad part he didn't say how he did it.
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Re: Recieve mod

Postby Goldfinger » Sat Mar 11, 2017 2:05 pm

That mod is strange 31. C12 is just a filter cap going to ground on the 8V receive line. How would modifying the PLL in any way change receive gain? Also, pin 14 on the PLL is not going to anything in the schematic.
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Re: Recieve mod

Postby 31 » Sun Mar 12, 2017 6:15 pm

GF, I did that mod way before I knew what circuits did what. I haven't thought about it till now. Looking at the circuit now makes no sense as to how and why it works. According to something I found online , pin 14 is the reference oscillators buffered output. As I said earlier, the mod just raised the volume and S meter for me. I never went back I tried it again after that.
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Re: Recieve mod

Postby Goldfinger » Mon Mar 13, 2017 9:00 pm

Right on.
I wasn't meaning to put you on the spot, I was just curious. I had never ran across that mod on the net yet. I see now that it's all over the place... lol
https://www.google.com/search?q=Receive ... 8&oe=utf-8
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Re: Recieve mod

Postby 31 » Tue Mar 14, 2017 5:36 am

No worries bro, I never take any comments to heart, this is all for fun and experimenting. It works but I can't explain why, it really is confusing. Why would something that deals with frequencies and go-no go situations, increase to volume of receive? Strange but it works.
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Re: Recieve mod

Postby 221 » Tue May 09, 2017 9:48 am

I tried it and it makes the receive loud but brings in alot of static also I put it on a switch so I can turn it on and off.

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