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rf gain mod for Cobra 19 dx 3 ?

G

gregcooper

Member
May 19, 2012
16
0
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Hi,
I am new to the forum and and had a question about the 19 dx 3. Can this radio be modded for rf gain? I got this radio for free and it works well, but rf gain would help, as this radio is really noisy. It is completely bare bones, no ANL/NB, not much of anything, lol. I have been looking for a while now for this mod for this radio, but I haven't had much luck. Any help you guys could give would be appreciated. I just need a newer,better radio, but this is what I have for now, and really can't afford much else.
Thanks
 

The only schematic I could find for this radio was so blurred as to be unreadable. Usually, the two AM detector diodes can be swapped out for a pair of equivalent Schottky diodes. The other mod would be to replace the 1st RF amp transistor with a better quality one. Aligning the radio would help too - if you have the tools to do that and know how to use them.

But I think that the old adage is still true: a $10 radio using a $100 antenna will sound like a $100 station; but a $100 radio with a $10 antenna will sound like a $10 station.

IOW, build a dipole antenna, put it up ~30 ft to its feed point, and use decent coax. That will end up working out when you can afford a better radio too. Cost almost nothing at all to make.

EDIT:
Adding/using a better external speaker rather than relying on the one inside the radio - would also help a bunch.
 
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schematic

I have this schematic I found, but I'm unsure if it is any better than the one you found.
Thanks
 

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gregcooper said:
Hi,
I am new to the forum and and had a question about the 19 dx 3. Can this radio be modded for rf gain? I got this radio for free and it works well, but rf gain would help, as this radio is really noisy. It is completely bare bones, no ANL/NB, not much of anything, lol. I have been looking for a while now for this mod for this radio, but I haven't had much luck. Any help you guys could give would be appreciated. I just need a newer,better radio, but this is what I have for now, and really can't afford much else.
Thanks
Click to expand...


What you have is a used ten dollar radio, there is no reason to do say 70 dollars of mods to a throw away radio. That said you cannot add an RF gain feature to a radio like that. There are receive mods or a receive alignment that can be done to better radio's.

An RF gain mod would not help improve the noise you are talking about. Cheap radio's have cheap parts, they are what they are. If you want better quieter receive you will have to buy a better quality radio.
 
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I think all a rf gain is, is a variable resistor on the center conductor of the coax. If you had an amp with a variable power on it you could disable the variable power and rewire the amp to use the variable power pot in the receive path. That way you would not be transmitting through the pot and cause failure of the pot and your radio finals. I don't see any other way of doing it because that radio is too small to fit a pot in to it even if I knew how. Also to build an amp without the amplifier section to do the same job the parts alone would be more expensive than a new radio.
 
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Thanks for the info. Boy, let me tell you, these little radios cause a lot of controversy, I get so tired hearing that they are $10 or throw away radios, they may not have all the bells and whistles of a Galaxy or a Connex, but they are still a radio regardless. I run a night transfer route from Pa to Md 5 nights a week, have been for years, but I have 6 kids, a wife, and all the bills of everyone else, and a company that doesn't pay crap, so this is the radio I have, and it's all I can afford for now, I would love to have a the newest Galaxy,or a much better Cobra but that's not happening anytime soon. It would be so nice when you ask a question about this radio not to be ridiculed or keep hearing your radio is junk, I already know that, enough of the radio bashing.
 
gregcooper said:
Thanks for the info. Boy, let me tell you, these little radios cause a lot of controversy, I get so tired hearing that they are $10 or throw away radios, they may not have all the bells and whistles of a Galaxy or a Connex, but they are still a radio regardless. I run a night transfer route from Pa to Md 5 nights a week, have been for years, but I have 6 kids, a wife, and all the bills of everyone else, and a company that doesn't pay crap, so this is the radio I have, and it's all I can afford for now, I would love to have a the newest Galaxy,or a much better Cobra but that's not happening anytime soon. It would be so nice when you ask a question about this radio not to be ridiculed or keep hearing your radio is junk, I already know that, enough of the radio bashing.
Click to expand...

Hey man if that's what ya got then run it. Just saying a used Cobra 29/25 on E-bay is cheaper then a new version of what ya got. Locally here a nice used Cobra 29 can be had every week for 30 bucks.

If noise is the problem you might try a noise filter on the power line to the radio and see what that does. Bandit and Magnum make a decent one. What kind of truck you running and what antenna? And I might add, what secret squirrel said is great advice. DTB is super. He might be able to go through that radio as you wait for a fair price.

Remember cb stands for constantly buying. lol
 
Thanks for the info on Dave's, I will see if i run close to there. I Drive an 06 International (day cab) and a 3' Firestick. I had the guys at the shop run me a power and ground straight from the battery, so dirty power isn't the problem. I really haven't tried a noise filter yet, most of what I heard about them is that they don't work very well, but come to think of it, that never stopped me before, lol. Where is that Cobra for for $30? lol, around my area they are running about $75 or better used, $30 I could afford. Thanks for comments guys.
 
I compare the little Cobra's to the little Undien's (510,520). Good basic radios that if you have a good antenna, add a power mic, they will hold their own. You can't really mod them that much but still worthy radios.
 
Yea, that's what I think too, just real basic. My only main problem with that Cobra is a whole lot of noise, it drives you crazy after 3 or 4 hours of driving, and that's not even close to half of my night, lol. if i could just find or make a good noise filter, I could tolerate it until I can get a much better radio. I had a Uniden 510, it had ANL, and it helped a lot, but the radio died not long ago, it was good too, clear receive and transmit.
 
Greg, try and explain your noise. Can you make the noise go away when you shut off the truck? Are you running any of the squelch control to block out the static?
 

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