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Post by chileansurfbum on Jul 6, 2010 22:11:19 GMT -5
Can someone out there help me out?? Im trying to make my radio a bit more powerful and I was wondering what I would need to do?? Basically I have a Cobra 29LTD Classic straight out of the box running with just the basic power and 5 ft Firestik antenna with no mods currently done to it please let me know what I can do to get more range and more power to my radio... thanks I am a full on Novice with this but I am looking forward to learning.
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Sandbagger
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Post by Sandbagger on Jul 7, 2010 9:30:47 GMT -5
Can someone out there help me out?? Im trying to make my radio a bit more powerful and I was wondering what I would need to do?? Basically I have a Cobra 29LTD Classic straight out of the box running with just the basic power and 5 ft Firestik antenna with no mods currently done to it please let me know what I can do to get more range and more power to my radio... thanks I am a full on Novice with this but I am looking forward to learning. There are shops and all sorts of internet published alignment mods which claim all sorts "improvements" which can be done to "boost" a radio's output. But IMHO, none of them will give you a significant increase in range or signal. Boosting a radio's output power from the stock 4 watts up to 6 or 7 watts is almost unnoticeable on the other end. The only real method you can count on for a noticeable signal boost, is to add on some type of amplifier. Yes, those are illegal, but so are any "mods" that you might do to a radio that push it beyond FCC limits. There are also things you can do to boost the modulation or "loudness" of the radio. These mods usually involve defeating the modulation limiter, and will make you somewhat louder, but at the expense of signal clarity and spectral purity. I know there are a great deal of CB'ers out there who don't care if their signal is "dirty" as long as they can "get out" better. I tend to prefer improvements that do not violate good engineering practice. The antenna system is also an important part of the system. Your Firestik is an ok antenna, but as a general rule, the longer the antenna, the better it is as a radiator (up to the full 9', 1/4 wave). Also, the higher up on the vehicle you can mount your antenna, the more omni-directional and better the radiation pattern will be. Of course, having a 9' antenna in the middle of a car roof is not really practical, but you might get away with a 6' open air coil antenna.
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Post by kosmic on Jul 18, 2010 9:18:06 GMT -5
Can someone out there help me out?? Im trying to make my radio a bit more powerful and I was wondering what I would need to do?? Basically I have a Cobra 29LTD Classic straight out of the box running with just the basic power and 5 ft Firestik antenna with no mods currently done to it please let me know what I can do to get more range and more power to my radio... thanks I am a full on Novice with this but I am looking forward to learning. To remain legal all you cando is tune properly. I have done many without moding them and getting great responce from them, good tune up and making sure you are properly alignedis the key. If you need help let me know and I will help you how I set mine up.
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Post by polebarnboy on Apr 16, 2011 22:38:28 GMT -5
i turned my vr4 to the left all the way. this will increase your modulation. i can get out about 4 miles or so and everyone says it is loud and clear. i had to turn my dynamike down to the 3 o`clock position also. not saying this will be what you want, but you can do it yourself with no meters and such. i learned the trick from cbradiomagazine.com.
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Post by Tombstone (R.I.P.) on Apr 22, 2011 14:30:25 GMT -5
Kosmic and polebarnboy said it all and I totally agree with Sandbagger as usual. Even if you can squeeze a couple of more watts out of that radio, it will make no difference on the recieve pertaining to other operator's reception of you. I too recommend an amplifier with more watts to really make a difference, and like said earlier, get that firestick up as high on your vehicle as you can. If there's no mounting problems a full quarter wave stainless steel whip should really help you out, as has already been stated. If that radio will peak up to over six watts or more, You're just straining the radio, damage could be done, that usually starts by causing power supply or regulator problems. You're good on turning the modulation pot to the max but clipping components in the modulation section will cause problems like the straining of parts in the radio as posted earlier. I never clip in the modulation stage unless you want a dirty signal especially if you put a power mic to it. I use a Cobra 148 GTL DX and once when I peaked it, just for fun I cranked it up to max power wise and got 12 watts out of it with PEP swing off of the scale on my meter. I turned it down to avoid damage to six watts just for an edge. When I connect up my one pill amp to it the power will be turned down to no more than three watts for a cleaner sound and probably have to turn the power mic down a bit too, I don't like dirty sounding rigs and if you take it easy and not over drive anything, the result will be a hard talker but clear sounding. I hope that we've guided you in the right direction.
Tombstone
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Post by car53wash75 on Apr 23, 2011 20:37:11 GMT -5
Get a 100 watt amp, it will do the trick
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Sandbagger
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Post by Sandbagger on Apr 24, 2011 9:15:38 GMT -5
Get a 100 watt amp, it will do the trick Agreed. A 100 watter gives you the biggest bang for the buck. Anything more than that and the cost and support hardware goes way up, while the signal gains diminish.
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Post by kf4ham on Apr 30, 2011 7:46:33 GMT -5
i agree with sandbagger. not much you can do to the radio for real improvements. your best bet is your antenna system. a lot will tell you this antenna or that antenna is better. i've tried a lot of them and the two i put my faith in and only run is, ether a wilson 1000 or a 108 inch whip. the longer the radiator the better. and if the 108 whip is prohibited then go with the wilson 1000.
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Post by car53wash75 on May 2, 2011 20:19:21 GMT -5
For a great antenna, check out the Wilson 1000, or the Wilson 5000{I have one of these}, both are worth the money.
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darknuss
Mudduck
The world is a cold free toilet..
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Post by darknuss on May 12, 2011 7:46:28 GMT -5
The OP didn't mention how he was running the radio. If it's in a mobile then I would run the power wires to the battery using a 7 amp fuse on the positive wire to allow a little more amperage. If using it as a base I'd recommend a 25 amp power supply and you can safely run the 29LTD at 14 volts. (I run my 29LTD Classic @ 15V) These things I mention will give you good results with a bone stock radio.
3's
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Post by gator7 on May 15, 2011 8:50:38 GMT -5
A few other things you can do. Have a CB shop put in a 1969 final transistor with a varible. And yes a 100 watt amp. You can use the radio with the varible wattage for most contacts. Only use the amp when the stock radio can't do the job. As for a antena, If you use the Cobra as a mobile. The wilson 1000 is a very good choice. I use one on my mobile. A steel whip or a 6' fiberglass are also good. And last, audio. A good power mic. All of these things will do the job. I run a cobra 25 with the 1969 and the varible. Also a 150 watt amp. Just a tune up and cranking a few pots won't help much. You need at least 10 watts for every db gain. (i think i got that right) In any event. You can always sell the 29 and use that $ for part payment on a good 10 meter radio. But the antenna is the single most important item in all this.
Good luck..
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Post by cbrown on May 16, 2011 12:52:56 GMT -5
I believe you have to quadruple your wattage in order to see a 6 dB gain (usually one S unit on the meter).
So:
4 -> 16 16 -> 64 64 -> 256 256 -> 1024 1024 - > 4096
That is why a 100 watt amp is a good buy; it gets your signal strength up 2 S units. A 500 watt amp will give you 3 S units.
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Sandbagger
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Post by Sandbagger on May 16, 2011 18:34:21 GMT -5
I believe you have to quadruple your wattage in order to see a 6 dB gain (usually one S unit on the meter). So: 4 -> 16 16 -> 64 64 -> 256 256 -> 1024 1024 - > 4096 That is why a 100 watt amp is a good buy; it gets your signal strength up 2 S units. A 500 watt amp will give you 3 S units. Yup! 4 watts to 100 watts is a 14db gain. 100 watts to 400 watts is only a 6db gain. 14db gain from 100 watts would be 2500 watts (and that's carrier power, not peak power) Yowch!
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Post by cbrown on May 17, 2011 9:16:34 GMT -5
Yup! 4 watts to 100 watts is a 14db gain. 100 watts to 400 watts is only a 6db gain. 14db gain from 100 watts would be 2500 watts (and that's carrier power, not peak power) Yowch! That would be one heck of an amp!
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Post by gator7 on May 18, 2011 6:16:59 GMT -5
CB, I guess I need to brush up on my wattage formulas. As for the 100 watt amp. It gives good bang for the buck. 50-$60.00 givens you a big improvement in output. Also I like the 100 watt amps for local talking. Less bleed over, and cleaner signal. At least in most cases. Of course it depends on what you buy. I have a galaxy 225 and a Texas star 350. Both do a great job.
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Post by cbrown on May 18, 2011 9:10:09 GMT -5
I'm a big believer in running just enough wattage to get heard by whom you are talking to. We have people here that will leave their amps on even when talking locally.
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Post by Tombstone (R.I.P.) on May 18, 2011 16:46:06 GMT -5
Yeah, I know people who run their amps even when talking local. I use swep tube amps and 6LQ6 tubes are way too expensive for that, plus that makes for causing interference to stuff resulting in hate and disconnect. Through the day I do leave mine warmed up but on standby, which is bad enough. I like to be as ready as possible if I hear skip. As far as the increase in "S" units, it's not worth it either but yesterday I was talking to a station about 20 miles away as the crow flies. At the other end, who I was talking to, started getting power line noise so I went to operate with my amp and cut through but only with an increase of one "S" unit. I was bumping 190 watts PEP.
Tombstone
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Sandbagger
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Post by Sandbagger on May 18, 2011 17:13:13 GMT -5
Yeah, I know people who run their amps even when talking local. I use swep tube amps and 6LQ6 tubes are way too expensive for that, plus that makes for causing interference to stuff resulting in hate and disconnect. Through the day I do leave mine warmed up but on standby, which is bad enough. I like to be as ready as possible if I hear skip. As far as the increase in "S" units, it's not worth it either but yesterday I was talking to a station about 20 miles away as the crow flies. At the other end, who I was talking to, started getting power line noise so I went to operate with my amp and cut through but only with an increase of one "S" unit. I was bumping 190 watts PEP. Tombstone I run my amp constantly. But my amp is set for a 30 watt (carrier) output, so it's not all that much. I run it that way for two reasons. One is that my signal never changes so unless someone knows, you really can't tell if I'm running power or not. The other reason is that my "neighbors" are at least 7 miles away, and with frequent jamming, every little bit helps.
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Post by Tombstone (R.I.P.) on May 18, 2011 22:14:10 GMT -5
Sandbagger, you're fortunate that your neighbors are that far away. I get the same reports on my amp that you do, I can switch from barefoot to 100 deadkey watts and they say that my rig sounds exactly the same, you can't tell that it's on. By the way, I gave up on the overcoupling thing when tunig the amp, it's hard on tubes. I tune it for max power modulated with about 90% modulation. It sounds really clean and clear.
Tombstone
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Post by cbrown on May 19, 2011 9:34:46 GMT -5
I run my Browning with my SB-200 on, but I deadkey about 60 watts with it on. A nice and easy drive, and my signal is nice and clean.
The guys I was talking about are the types that drive their amps into distortion so they can brag about the watts they are pushing.
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Sandbagger
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Post by Sandbagger on May 19, 2011 10:03:14 GMT -5
Sandbagger, you're fortunate that your neighbors are that far away. I get the same reports on my amp that you do, I can switch from barefoot to 100 deadkey watts and they say that my rig sounds exactly the same, you can't tell that it's on. By the way, I gave up on the overcoupling thing when tunig the amp, it's hard on tubes. I tune it for max power modulated with about 90% modulation. It sounds really clean and clear. Tombstone When I said my neighbors were that far away, I was refering to my CB local neighbors, not the people next door who COULD be getting TVI from me (I haven't heard a complaint yet though). Yea, overcoupling needs to be done properly. If you go too far with it, you risk running the tubes out of resonance which will cause them to draw more current and that will shorten their life. I've found that it's better to peak the amp at maximum drive, for maximum output, and then reduce the drive power until your carrier power out of the amp is no more than 25% of your max peak output. At that point, your signal will be clean and with no backswing. Although you shouldn't apply max power until the amp's tuning is "close", and you only need to touch it up for the peak power out.
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Post by gator7 on May 20, 2011 6:00:16 GMT -5
Well, I see the discussion has taken a direction of base amps. I was referring to mobile amps when mentioned local talking. I do most of my talking from my mobile. I use it on stage 1 of 3 stages for the most part. We have major issues with line noise, and traffic signal RF here. In many cases, if the person I am speaking to is ruining stock. I can't hear them. So, I run the mobile on the 1st stage just about all of the time. We also try to keep 10 to 12 channels from the local channel. That also helps. One thing is for sure. We answered all of the questions about peak and tweak. LOL
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Sandbagger
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Post by Sandbagger on May 20, 2011 8:08:09 GMT -5
Well, I see the discussion has taken a direction of base amps. I was referring to mobile amps when mentioned local talking. I do most of my talking from my mobile. I use it on stage 1 of 3 stages for the most part. We have major issues with line noise, and traffic signal RF here. In many cases, if the person I am speaking to is ruining stock. I can't hear them. So, I run the mobile on the 1st stage just about all of the time. We also try to keep 10 to 12 channels from the local channel. That also helps. One thing is for sure. We answered all of the questions about peak and tweak. LOL Running a solid state amp on the "low" setting with a 4 watt radio is a good idea. Most single stage solid state amps can be driven to full output with 2 watts of drive. You are not alone in the noise department. I've noticed a slow but steady increase in the static and buzzing type noises over the years. I hear it from the AM broadcast band, all the way up though 220 Mhz. I don't know if the cause is mainly from breaking down electrical infrastructure, or from newfangled digital gadgets, or a combination of both. All I know is that driving around mobile and trying to hear weaker stations is getting much harder to do. I can remember back in the 70's, barefoot mobiles could talk to each other at distances up to 10 miles apart. Nowadays, you need 50 - 100 watts to do it.
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Post by Tombstone (R.I.P.) on May 20, 2011 12:05:30 GMT -5
Yeah, when riding around in a mobile set up, I also think that It's almost a must to be running some power. Sandbagger, my base amp is putting out about 175 watts of PEP power. I figured what you said about no more than 25% drive to the amp and I see that 25 % drive would be 4.375 watts. I'm driving my sweep tube amp with 3 1/2 watts out of my Browning Eagle S23 transmitter so according to these calculations, if they're right, I'm driving the amp easy enough that it results in a nice clear signal.
Tombstone
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Sandbagger
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Post by Sandbagger on May 20, 2011 14:12:04 GMT -5
Yeah, when riding around in a mobile set up, I also think that It's almost a must to be running some power. Sandbagger, my base amp is putting out about 175 watts of PEP power. I figured what you said about no more than 25% drive to the amp and I see that 25 % drive would be 4.375 watts. I'm driving my sweep tube amp with 3 1/2 watts out of my Browning Eagle S23 transmitter so according to these calculations, if they're right, I'm driving the amp easy enough that it results in a nice clear signal. Tombstone The most important thing is to set the OUTPUT carrier from the amp to 25% of its PEAK rated power for proper AM modulation headroom. Whatever your radio's drive power happens to be to achieve that point is relative. If your amp puts out 175 peak watts max, then you need to set your drive power so that your dead key power out of the amp is 25% of 175 watts or about 44 watts....
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Post by Tombstone (R.I.P.) on May 20, 2011 15:30:48 GMT -5
Hmm........ something's not jiving here. A well known tech on this board told me about overcoupling being hard on the tubes. He told me to peak the amp modulated with a HELLO, which results in the amp putting out 175 watts PEP, that's all it will do. I installed a switch on my D104 G stand that shuts the crystal off so that there's no chance of any modulation from room noise. That's how I was peaking the amp when I was over coupling it, I would keep turning the load control and dropping the dead key about 20 watts. If I want 44 watts out of the amp dead key, I would really have to overcouple it and I wouldn't get 175 PEP watts out of it. Right now with it putting out 175 watts, it's dead keying 100 watts. That's with 3 1/2 dead key watts out of the Browning. As you know, there's no variable power on the S23 transmitter, just the two plate and load adjustments on the side, which I peaked with no modulation. The way I have the amp peaked now is resulting in the 175 PEP watts, and I have the modulation pot in the transmitter set for about 85 % modulation. That's arm's length away from the mic. I'm getting good reports with the amp on, they say that it's loud and you can't tell if I'm running power or not, it sounds the same. It really didn't make any difference in anything from when I was over coupling, I just know that I'm not stressing the tubes. I think that I'm set up correctly unless you have more suggestions for me.
Tombstone
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Sandbagger
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Post by Sandbagger on May 20, 2011 16:18:42 GMT -5
Hmm........ something's not jiving here. A well known tech on this board told me about overcoupling being hard on the tubes. He told me to peak the amp modulated with a HELLO, which results in the amp putting out 175 watts PEP, that's all it will do. I installed a switch on my D104 G stand that shuts the crystal off so that there's no chance of any modulation from room noise. That's how I was peaking the amp when I was over coupling it, I would keep turning the load control and dropping the dead key about 20 watts. If I want 44 watts out of the amp dead key, I would really have to overcouple it and I wouldn't get 175 PEP watts out of it. Right now with it putting out 175 watts, it's dead keying 100 watts. That's with 3 1/2 dead key watts out of the Browning. As you know, there's no variable power on the S23 transmitter, just the two plate and load adjustments on the side, which I peaked with no modulation. The way I have the amp peaked now is resulting in the 175 PEP watts, and I have the modulation pot in the transmitter set for about 85 % modulation. That's arm's length away from the mic. I'm getting good reports with the amp on, they say that it's loud and you can't tell if I'm running power or not, it sounds the same. It really didn't make any difference in anything from when I was over coupling, I just know that I'm not stressing the tubes. I think that I'm set up correctly unless you have more suggestions for me. Tombstone No, what I was referring to in the previous post is not to set the dead key power via overcoupling, but by reducing the drive power from the radio. Overcoupling is just a way to get around excessive drive. But it can only correct a small amount. If your radio has no easy way to drop the carrier power, it becomes more difficult. What I've done in cases like that is to build a variable pad in the input of the amp, like they have on some of the competition amps. It serves 2 purposes. One, it allows you to set your drive for best headroom without overdrive regardless of how much power your radio puts out. Secondly, it forces a 50 ohm match which makes your radio happier. Some amps have really poor input SWR, and might even show close to 3:1 on the radio's SWR meter when the amp is keyed. But with a 50 ohm resistive pad, the match will be very close to 1:1.
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Post by Tombstone (R.I.P.) on May 20, 2011 17:05:49 GMT -5
Ok, I think I see now and my calculations must have been right. When I did the math on my calculator, it told me that the drive to the amp from the radio should be 4.3 something, which when rounded out, it would come to 4.4 watts. The Browning is putting out 3 1/2 watts. so I still have a little headroom. As far as the way I have the amp peaked at 175 PEP watts without overcoupling and dead key watts or so, I have headroom there too, so as far as I see, I'm ok. Besides, if I wasn't correct on the tuning, the amp would sound bad and you would be able to tell when I'm running power and you can't, it sounds the same as barefoot. Thanks for the help, Sandbagger.
Tombstone
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Post by gator7 on May 22, 2011 10:08:37 GMT -5
Too bad that most of are operators here don't read this forum. They think that its fine to drive the amp to the max. Of course they splatter all over the place and sound tight. Or just way over driven.. Oh well, its the CB way.. And I think Florida Power is using the high tension wires for data transmission at times. the type of static and interference is of a variable nature. So times it is true line noise. Other times it sounds like data is mixed in with line noise.
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Post by cbrown on May 23, 2011 9:36:00 GMT -5
A lot of places were trying broadband of their power lines. That could be the noise you are encountering, gator.
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