Ekka (Kannada) [2025] (Aananda)

Cb radio no modulation. but is throwing a solid carrier but 1.

Cb radio no modulation. Mic and mic socket checked and double checked - all OK. The RCI 8719 - A PLL works j Citizens band radio (CB radio) is a land mobile radio system, a system allowing short-distance one-to-many bidirectional voice communication among individuals, using two-way radios operating near 27 MHz (or the 11-m wavelength) in the high frequency or shortwave band. Wrong. Is this something one can do himself at Oct 14, 2012 · Hello, I am wanting to adjust my deadkey on my Cobra 148 and my Uniden Grant XL. Dec 21, 2020 · First thing to try is usually the easiest, swap the mike. Is there an audio tracer available for this task? Thanks in Dec 24, 2020 · But I have no audio (modulation) SSB I can hear a crack on external speaker as soon as I press the mic but I have no audio. I will continue to work and fix this realistic trc 453 it’s a very nice small form factor Radio and I would love to have it in my vehicle Today Our songs are get down on Apr 29, 2005 · I have aCobra 29 LTD Classic on the binch, it has no output power. Elimination of individual station licenses results in no lessening of the operating privileges or responsibilities of CB users. Is a 1998 cobra 29 with a KEPL-255 board. Any ideas? I did a full electrolytic cap replacement several years ago. It's on frequency, transmits at 8-12 watts. If you know the mike is good, start following the audio signal through the radio. Issue: No AM output Checked: AM receive - great SSB receive - great SSB output - great both modes Alignment - great, all freqs deadon. It works great, just the power is lower than I am used to seeing on the chassis'. My question is how can I trace the audio through the board to find out where the loss of the modulation is happening. Put on SSB shows no modulation on meter like AM does? Plug speaker in PA switch PA on and it has audio out. Includes cross-reference chart. Weak receive, low volume. 300 to 28. 965 – 27. Aug 7, 2011 · I have 100 percent modulation, it's snappy, and at the bottom of A band, and top of F band, 27-29 watts PEP Am, 34-36 SSB, in the C-D bands, I see 30-33PEP AM, 40-42SSB. Therefore, these industries have to install these cheap circuits which make you sound like this. Where does the sound come from? Is the CB Our friendly & experienced staff is here to help. Apr 29, 2014 · Picked up my first cb radio today used off Craigslist owner said it works great! It's a cobra 148 nw st soundtracker The channel number light up and so does the meter but not the faceplate like I think it should, also the meter never moves on transmit or receive , I did read the Manuel " 11. Jun 28, 2023 · What is FM CB radio? Radio has high-frequency audio signals that can be transmitted and obtained over radio waves thanks to the radio broadcasting era, often called FM radio or frequency modulation radio. Mar 9, 2021 · Re: Harrier CBX Low RX audio and no TX modulation by ChubbyChops » 07 Apr 2021, 13:52 Thanks for the reply. There is a reason that good cb techs are very busy. Let's remove the audio bottleneck and Install a solid state modulator (darlington configuration used here). 80v 10. Fuel your knowledge, unlock secrets, and engage in discussions. Here is his cobra 29 ltd with no tx. prcguy Apr 29, 2011 · How do you turn up the modulation on this radio? FYI it has the PC-385 board. Once home, I connected to a Dosey meter to check the AVG and PEAK readings and then MOD % Dec 14, 2020 · I have a 2000 that receives well, both in CB, and PA. Also, the pulse width, or duty cycle, is precisely controllable assuming that you are using a function generator that has this capability Aug 30, 2022 · Hello everyone I have purchased this radio a couple of months ago not wide banded. A. 80v Still no transmit and does not try to switch to transmit. Using a signal tracer can really speed up the process of finding out were you have and lose modulation. PA doesn't transmit a voice either. showes it has good signal but no one hears it - CB Radio Depending on how the radio generates amplitude modulation, you likely have an issue with an amplifier somewhere in the transmit chain. After reading some on the radios I believe VR10 adjusts AM power and VR11 is SSB power. To understand how CB modulators work, it's essential to grasp the basics of modulation. Secret CB Index By Model Realistic Just got a uniden in PC244 off eBay On the test bench it went a. FM mode operates within the same standard AM frequencies used for CB radios 26. FREQUENCY RANGE The COBRA 148GTL transceiver represents one of the most advanced SSB/AM two-way radios ever designed for use as a Class D station in the Citizens Radio Service. Nov 15, 2012 · I bought a radio that seems to do everything right but has NO modulation. Apr 6, 2005 · AMC = Automatic Modulation Control (adjust to no more than 100% modulation). However, I don't get any sound at all even when I turn the volume and squelch back and forth. Unlike AM (amplitude modulation), which uses changes to the sign’s amplitude to transmit information, FM radio broadcasts audio by growing the sign’s frequency. Tubes check good, bypassed the mic gain control but no hum when touching connections. 12. But any useful tool can be abused, and the carrier control "swing kit" is no exception. had been working great but now it has me stumped. Sep 20, 2020 · If the amp dead keys at 100 watts with no modulation, it will need to put out 400 watts peak when the radio is fully modulated, otherwise you get a bunch of distortion and only a fraction of the range increase that you would have if its working properly. No hum buzz when I touch the audio pin on mic socket. Feb 6, 2020 · Either it is a portable CB radio or the base type CB radio, you need to fix the problem. 69 tx May 18, 2022 · Reducing the radio's carrier so that the audio coming from the linear sounds like the barefoot radio sounds is the main benefit of this trick. If there are high SWR readings or no continuity, it may indicate issues with the radio. What gives ????? Basic troubleshooting and signal tracing procedures to repair a no modulation condition. 34v TA7222P 1. I have no signs of a dielectric capacitor expansion. - Frequency adjustment - Perform a This mode consists of modulating an RF carrier. I tested it a spare antenna and with my existing car rig (Cobra 19 Discover how do cb radios work with Crate Club—your ultimate source for premium tactical, survival, and self-defense gear. Boost your CB radio's power and sound quality with our comprehensive guide. thanks for watching like, subscribe Mar 20, 2018 · My Cobra 25LTD, the back-up radio I used on my trip to SC and back has no modulation all of a sudden. Be sure that TR24 is in the radio too, as removing it will give better AM modulation; but at the cost of outright ruining SSB transmit audio, as well as making for a horrendously distorted audio signal on the scope. My question is, how or is there a proper procedure to tune these? Do you have the mic Cobra 2000 GTL AM/SSB CB Radio Review I can still remember the first time I saw a Cobra 2000 GTL at my local CB shop. i was gonna play with the am power and mainly the modulation,as this is the sickest radio ive ever had to be honest,and i dont no much at all. Working on your own CB - adjusting the modulation ** Warning performing modifications on a CB radio can be a violation of FCC regulations. Apr 4, 2008 · Radio has no tx. All switches/knobs work as new Meter and all lights work as new No Feb 2, 2011 · As I have found, not many people know how to do this. Tracing it is pretty straight forward, with a tone generator and an O-scope, but without that, swapping in a corded headset could help testing via the intercom. this mod will give you a variable dead key using VR4, the modulation adjustment VR. Jul 8, 2010 · Lets Explode a Few CB Myths 4) To get out you need lots of swing in your AM signal. Most radios power supplies and mod transformers can not even hit 100% well without severe distortion, ie splatter. Why Do I Need to Peak and Tune CB Radios Typically, manufacturers set their CB radio’s output wattage and modulation a bit lower than legal limits. Your Mic Gain affects this latter number. It doesnt Oct 18, 2022 · Hi, when I key this transmitter up I am getting a 4 watt dead key but no modulation in AM but am getting modulation on SSB, I have seen it recently modulate on am as I was wiggling the 12ax7 tube but has stopped all together, I figured it was a loose and or dirty tube socket so I cleaned it and Aug 30, 2022 · I am currently working on a cobra 29 ltd. While this article does touch on some radio-related topics, it is important to emphasize that troubleshooting and resolving problems often involve addressing issues with the antenna, coaxial cable, or grounding rather than blaming Apr 3, 2005 · Modulation is low and distorted, no receive audio, no PA audio. - Aligning the receiver - Adjusting the squelch range - Calibrate the transmit and receive meter settings. The amount of modulation is directly affected by where you have the Mic Gain control set. This is a modification to the Uniden Pro510XL CB radio which replaces Jim Bare's original audio modulation method with a direct RF modulation method. As a result, nonsense CB folklore has filled the airways for decades. Keep both your CB radio and the modulator clean to ensure optimal operation. 13. Avoid Overmodulation: While the Top Gun modulator enhances modulation, it's crucial to remain vigilant against overmodulation. Tubes check good, bypassed the microphone gain control but no hum when touching connections. m. Redwire,yes it is a mess inside that will get tidied up,will add pics. Listening from another radio all you get is a dead key. When I press the microphone button the needle sweeps back and forth. This radio had work done to it at a previous Oct 12, 2013 · Good evening, everyone! I was wondering if anyone had some advise of a fix for a radio I have. No issue with modulation No modulation on: AM…. no dead key no swing put it in PA mode plug in external speaker to PA port talk to your self all day long straight pin audio chip i found a link on CBTRICKS A CB radio and a broadcast transmitter both produce AM radio, just like a flashlight and a laser pointer both produce light. This unit features advanced Phase Lock Loop (PLL) circuitry, which is used in the AM mode and in the upper and lower single sideband modes, providing complete coverage of all 40 channels shown below. every cb trick web site has the same thing listed for adjusting it "i checked" . Learn about antenna selection, modulation adjustment, and the use of amplifiers. com. but is throwing a solid carrier but 1. They may tell you that you're anClipping your Apr 6, 2016 · radio has good receive 5 watts on key up just no modulation output. Secret CB Index By Model Cobra (Dynascan)Documentation Project CBTricks. 43 rx 0-6. Clean and easily changed up to use the RF gain on the face is desired Apr 18, 2008 · Ok I put the TA7222p in and the MB3756 into the board with new IC chips. 40,42,43 and 44 were all tuned low. The question is actually something that everyone who uses the CB radio should be asking themselves. The last guy I paid to do this ended up snipping the modulation limiter in the radio causing it to distort. 69 tx driver=0-13-. Theradiogarage@gmail. Key up talk and mod meter swings up but no power or audio out. High deadkey with small swing=undermodulated (bad). Surprisingly we found out that even brand new untouched from the factory the radio was set below the factory settings. We specialize in radio brands like Connex, Cobra, Galaxy, General, Magnum, Ranger, Stryker, Uniden & J&M motorcycle CB radio systems. Everything else Jul 12, 2020 · Im tinkering with this radio and with the external Dosy swr/watt meter is show dead key 4 watts key up no swing no modulation no movement same goes for the radios meter, its a new cobra power mic and yes i tried another mic too Can someone lead me in the right direction please? Oct 13, 2016 · I have a somewhat newer 29 ltd classic, 2011 model. No obvious visual signs of failure and radio appears to be unmolested. People may get upset at the mere mention of clipping a modulation limiter. Jul 8, 2010 · Tell me this, when you are using the amp with that 2 watt deadkey from the radio, what does the amp deadkey without modulation? It should be around 45-55 watts. PA NOT working. On ebay people often will tell you that the radio they are selling has had a swing modification done to it to make it a “screamer”. cercut works with nice loud audio. SSB is uncopyable. If you actually start cracking the radio theory books and start learning legitimate radio Jun 29, 2016 · I took the top off my new President McKinley radio and was looking to find the modulation pot. . I changed the drive and final transistors, IC-4 poweramp, And TR-3 x-mit/rec. Still interesting though. Fixing no transmit and no modulation issues with uniden and galaxy radios Members only The Radio Garage 12. CB radio, fully named Citizens band radio, is a personal radio service that allows two-way communication between short distances. Get instructions to maintain performance and ensure reliable communication. When keyed in AM mode its making a hum and swinging it to full wattage. The P. FM transmits, but with no audio, and SSB does nothing. I have replaced many caps already,particularly the 10v ones. **NEW** Cobra 148 NW ST Top-of-the-line CB Radio With SoundTracker and backlit front panel Cobra 148F (Discontinued) Cobra’s top-of-the-line SSB Mobile with Frequency Counter. I'd like to preface this discussion with a plain and simple truth about CB'ers. How to fix Vintage Johnson Messenger 1 tube type CB No modulation or audio Yep another stupid cap! D-lab Electronics 79. . I got a Cobra 29 LTD Classic off of a friend of mine. My Tram 201D has lost modulation. 1. I have a Sears RoadTalker 40 when i key the mike the transmit light lights up as for the mod light it want light up at all and the modualtion neddle want move at all Aug 13, 2008 · I take it that you turned up the modulation pot before you clipped the resistor. Boasting over 450 watts PeP, it puts everything else to shame in terms of performance. in the CB mode the green light turns to red like it is supposed to, just no output carrier or modulation. Upon advice from Mar 24, 2019 · Hello guys bought uniden washington radio at thrift store has no modulation. WHAT IS MODULATION? Well the actual definition of modulation as it refers to CB radios involves a fairly technical explanation, but we ll try to keep it simple. After 13 years in a box I wanted to try the old Cobra. That leaves you with more downward modulation than upward. Strange mods, 2 look like some sort of clarifier mod (1 on bottom of LSB sensitivity adjustment L13, 1 on bottom of LSB PLL Offset Osc. - Turning up the Transmitter's wattage - Adjusting the modulation for maximum output without distortion. The modulation goes up normal and so does swing when I key up with rodger beep. so a brought a KPO power mic NM-5 Jan 29, 2010 · Just another observation, does the meter appear to have ever been replaced at all? If so could it have possibly been wired backwards? If you're showing a good modulation on an external meter, then odds are it is something with either the metering circuit or the meter itself in the radio. You can use a CB radio for short distances and establish bi-directional radio communications. Recieves good, power out good 5w, but No modulation. to turn it up a hair, which must be RT206. Your CB radio has a maximum of a 4 watt AM carrier, when measuring the peak envelope power, or PeP, most CB's have between 9 to 18 watts modulation. 0v 3. Yes, tried different mikes and mike gain is on. 95-. It is widely used for exchanging information between drivers and in casual conversations, as well. Learn how to test a CB radio and troubleshoot common issues. I do not have any carrier on TX on AM, and no modulation on SSB. Best case, the radio should sound as good with the linear activated as it does by itself. An AM signal is fully modulated when the "swing" doubles the carrier. They're talking about dead carriers of just a few watts and swinging to over 20 on a modified CB? Aug 13, 2008 · If you have a stock CB that has an Un-modulated carrier (Dead Key) of 4 watts and a Modulated carrier of 16 watts PEP (Swing?), you then have 100% modulation Oct 31, 2012 · Next in the stack of radios from the unknown. Jul 30, 2025 · Learn how to calibrate and reset the antenna warning on your Cobra 29 LX CB radio. Oct 24, 2023 · Dust and debris can accumulate over time and adversely affect your CB radio's performance. 37v 7. So what exactly IS the famous “super modulation Recieved a couple radios and a mic for repair from the same customer. Dec 22, 2014 · Realistic TRC-55 Everything normal, signal strength good, swr check works, mic operation for both (on the air) (modulation) work as normal when transmitting, just no volume, even pa works. but what is PLC?? I see AMC RT206, PLC RT202 201 is the meter, 205 is drive bias 204 is final bias, 501 is freq Got AM-S and SSB-S, 101 is ASC Sep 16, 2020 · Now the displayed frequency does not change on the front of the radio, hot , cold, or in between! the problem I have is that the radio has no transmitted audio now. All worked fine, but with quiet modulation. 405MHz. No electronic knowledge required, and you use the radio’s own S/RF panel meter or an inexpensive SWR meter for tuning. Sadly, there is no modulation. An operator of a CB radio station is still required to comply with the Communications Act and with the rules of CB Radio Service. Connect with CB radio enthusiasts at CB Radio Talk Forum. 5 watts Tried 2 different mic's for giggles and same results. But the radio all tuned up gets me 1-4watts AM, and 8-9 watts SSB. Asymod II Hi Fi Asymmetrical Am Modulator for CB Ham Radio Transmitter | eBay Pretty cool but who can explain how it works? Or is it snake oil? RADIO CODE DEFINITIONS 10-CODES The following list contains common “10-Codes” used by CB radio operators for faster communication and better understanding. No hum buzz when I touch the audio pin on microphone socket. This custom-made 40-ch CB radio modulation tuning adapter cable is made for use on the 2018-2023 Honda Gold Wing GL1833. Proper testing can help diagnose and troubleshoot the problem. 3258MHz in them " You really just need 28. 0v 8. Still no output Jun 27, 2021 · Got another weird one on the desk. The last time I was heard by somebody was in NC when I got a radio check; no problems with audio then. WARNING - TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE. When I key the mic. Is RT4 the same as VR4 ? Any answers greatly appreciated. 0v 9. It’s one of the most popular modifications to have done to your CB radio. This is a DAK CB with transistor receive and tube transmit. what has been tried all new caps check all tr Jan 15, 2017 · I have a galaxy 99v the transmit doesn't work, but pa and rodger beep does. If you put it in PA mode with a speaker or headphones plugged in, do you hear anything? President Jackson CB-Radio ALIGNMENT PROCEDURE TRANSMITTER PORTION Test equipment required: Secret CB Index By Model President / Uniden Jun 29, 2012 · C F Galaxy user's question on ssb and a slight deviation on frequency firefighter_21701 Jun 8, 2018 CB Radio Forum Replies 6 Views 3K Jun 11, 2018 kc4jgc Jun 21, 2024 · Modulation is the process of varying a carrier signal in order to use that signal to convey information. If the finals are already operating near the voltage rails to achieve that 900w DK, there is no way to get positive modulation. 060MHz to 28. Still no receive in AM even though its transmitting a signal. Dec 20, 2020 · It transmit normal carrier and RX is fine. It powered up okay, the display only works on bright, but I didn't think it was a huge problem. Get expert tips, guides, and tools to stay prepared for every mission and challenge. Issues: No modulation on any mode, good carrier. Oct 1, 2021 · After considering this additional information, we conclude that allowing manufacturers to add FM as an optional modulation scheme will not substantially change the fundamental nature of the CB Radio Service and will improve the user experience, as described by Cobra and President. There are CB radios that do not have an adjustable potentiometer for modulation, and simply use a fixed resistor. Jan 14, 2022 · If it has RF power out, (the RF meter on the radio goes up to around 3- 4 watts), then the RF driver transistor and RF final transistor (only one final as it's a cb radio) are okay. keys 4 watts and swings forward to 5 watts with a 575-m6 power hand mic. It dead keys fine, but no modulation or swing. Mar 10, 2019 · ive got a general lee it works fine on hi power but no modulation on low power Nov 19, 2012 · Well, it was time to dig out the old base. you no that tho lol. ANY Performance tune up - 40 channel mobile CB The Performance Tune Up includes the following changes in order to enhance the radio's performance. Anything more than that is distortion to your Dec 3, 2021 · I am not disappointed. If I touch pin 4 of the audio chip I Apr 6, 2005 · well glad you caught me as this was fixing to happen with the vfo check. Radio receives fine. This is a circuit board model that has good receive audio on AM or SSB and dead keys 4 watts right on frequency in either crystal or VFO modes. You ll often hear on the CB radio one operator asking another how is my modulation? . Specifically the Bias and Voltages were extremely low. 4K subscribers Subscribe The CB radio & mic industries have to adhere to the FCC’s rules & regulations regarding over modulation. Is it good where the "Dynamike" (mike gain) control connects to the main board? Oct 25, 2020 · Cobra 29 LTD came in with a no modulation issue. The meters on the radio so modulation, but the swing meter Detailed alignment instructions for Realistic CB Radios, including voltage adjustments and frequency tuning, to optimize performance and ensure accurate operation. I'm unable to turn the dynamic control down or anything. Additionally it can be dangerous and may expose you to electrical shock, injury, or death. Basically an audio-frequency wave must be May 3, 2011 · cobra 29 ltd wx classic, good receive no transmit. The other mod looks like some Make sure you are heard with the Ranger RCI-69FFC6 10-meter radio. Aug 7, 2011 · Well, the radio is aligned, and talks fine. Can be used with existing CB setups. Feb 8, 2020 · 2003 Cobra 29LTD no meter movement, no sound at all, no receive. I'd bet that the reduction in SWR with modulation is a result of the downward Oct 13, 2012 · There really is no short cut or basic way to properly tune a radio when you don't have the proper equipment and know how. 0v 4. PA also does NOT work. All new Frequency Modulation (FM) mode for CB radios, offers superior audio clarity over standard AM. Example: papa-mod for a superstar 3900. Most CB'ers are clueless about radio theory. Its pinning the S/RF meter in AM. The more the wave amplitude is modulated, the virtual output power will seem higher, thus achieving a noticeable power May 24, 2009 · Stumped, no sound or nothing???!!! Discussion in ' CB Radio Forum ' started by Freudian Trucker, Sep 6, 2009. Cobra has really shot themselves in the foot with this new radio, why you ask? I'm getting to that but first let me say that Cobra has been the industry leader in producing good quality CB radio's down through the years, there was the great line of Mobil "AM" radios such as the 25LTD, 29LTD. 38v 4. If the problem is about module adjustment, then you follow this article and adjust the modulation system inside the CB radio. voltage readings on final (1969), driver (2166), regulator final=0-13-. Radio keys up and has power and receive but will not modulate carrier. L21). and sideband however no transmit power coming out of upper side band or lower. You’ll often hear people say on the radio that their Cobra 29 LTD has had a “swing mod” or “Super mod” done to it. So I then put the radio inline to see what was really happening. 13 rx 0-6. The difference with the Pace radio is it will make full legal power running the final at reduced voltage and will go well beyond legal power when modulated after a minor mod is done. 18v 7. In the case of CB radios, modulators can improve the performance and range of the communication system. CB Radio service and repair. 0v 5. Still scouring online for a service manual. Jan 15, 2025 · Looking For Best CB Radio in 2025? Read Our Latest Top 10 CB Radio Review with Detailed Comparison, Specifications, and Unbiased Advice. From 0-max dead key. Issue: Has modulation if you swallow the mic on: LSB (low to Good), 8-10 watts output USB (low), 5-7 watts output PA works fine. I've tried a couple different microphones as well. But no modulation at all in AM or SSB or PA . Signal tracing a no modulation on a Cobra cb radio. It has good receive and good wattage, but has no modulation at all on low power but it peaks around 20 watts on the hi power setting. I was able to determine that it would receive when wired for a Midland mic and everything worked except for there was no modulation. CB radios are essential communication tools for many Offers another mode for CB radio - historically, CB radios were limited to AM (Amplitude Modulation) and SSB (Single Side Band) modes. The on air lights up when keyed. DK too high. Jun 27, 2021 · Got a Galaxy SSB Echo Base on the desk today. 500 for voice, the lower part of the band is CW. Any help would be appreciated. This simple in-line adapter cable from J&M controls the mike level output from the main audio system to the CB radio, so that an over modulation condition does not occur during CB radio transmit. I'm far from an expert but I know a few basics. I wonder what the deal is? There are no swing mods or nothing either on it. Deadkey at 1/4 of full modulated Cobra 29 LTD Classic Fixed (NO RX AUDIO, NO OUTPUT AUDIO) The problem I found with this radio was the audio chip had failed due to age of the radio. I replaced D77 with 2 1n4148 in series aND tr38, still nothing. Results Guaranteed! Notice: For Citizen Band Radios: Internal modifications of any type void type acceptance granted by the FCC. 47v 2. I had gone in to have my Sears Roadtalker 40 looked at to see if they could fix a modulation problem and while I was waiting I ended up Cobra 2000 GTL AM/SSB CB Radio Review I can still remember the first time I saw a Cobra 2000 A quick videoxon how I repaired a no modulation on a Realistic powered base microphone. Board is a PC-833AE any ideas greatly Jan 2, 2020 · modulation transformer is an obvious audio bandwidth choke-point or bottleneck when Hi-Fi experimenting. 5K subscribers Subscribed Nov 11, 2024 · To determine if a CB radio is bad, check the SWR readings and test the antenna and coax connections for proper continuity. regulator, and a couple misc. No static, nothing. 500Mhz (Ham 10 Meter) operation in Cobra/Uniden CB's that originally had 11. Again no AM modulatio Jan 24, 2023 · To peak and tune, a CB radio generally means to improve its performance by doing a couple of things, such as increasing the wattage and adjusting the modulation. Oct 17, 2020 · Re: President Madison CB radio repair Many thanks for the replies, Last night I managed to repair the PA section,For some reason,someone had added a diode to the relay,which went to the middle pin of the PA switch. The 8v switches as it should. 53v 5. Pots have Detailed information and specifications of the SBE Trinidad II (SBE-30CB) CB radio, including features and functionalities. This wikiHow article will teach you how to install, peak, and tune a CB radio Jun 8, 2009 · Hello, I'm pretty not new to CB radios, but I am new to fixing them. 52v 3. Zero modulation on AM, but there is a carrier. Its bone stock. The modulation can be increased by speaking more loudly or using a power microphone. Aug 10, 2015 · Really cool board I found on ebay that allows 300% modulation with no distortion. The CB band is filled with average joes with no formal electronics training trying to guess at radio theory. The MB8719 PLL was bad. 6908MHz gives 28. 0v 6. May 27, 2023 · The majority of CB radio problems are typically not related to the radios themselves but rather to problems with the receiving cable, coaxial link, or installation. Also reflowed solder in these Jun 13, 2023 · no modulation This forum is for general discussions, and you are welcome to post in this forum if you are not able to find the right place. If the radio works the most I would do is adjust the AM dead key, SSB peak power, and modulation to what you want or need. Does not require changes to your antenna system. They are the side mic models. Clipping your modulation limiter Cobra Uniden Antenna Amplifiers Microphones Cb radio reviews modifications Cobra Uniden Antenna Amplifiers Microphones Cb radio reviews modificationsClipping your modulation limiterIt's often referred to as the biggest no-no in CB radio. It has full output on high and low power, but NO modulation. Why? Because in May 14, 2025 · CB (or Citizens Band) radio is a type of radio mainly used in semi-trucks or by hobbyists that transmits and receives signals using Amplitude Modulation (AM). Dec 15, 2020 · I got the radio working again but it's not right. A page which lists the adjustments for ther uniden and president range of cb radio's A page which describes how to align the Cobra 148GTL CB radio. Issues with the swr/cal s rf meter and switch no Apr 29, 2025 · The OP needs to hear the radio himself against perhaps some other units without modulation limiters clipped and adjusted properly then decide if there is really a problem or not. I have a Uniden and a Cobra with a Uniden board I thought of wanting to do this on. That is to reach 100% modulation a 4 watt key should swing no more than 8 watts. A Citizen Band or CB radio signal without modulation is a carrier wave. 18v 6. Jul 29, 2022 · The attached one page document talks about downward modulation, but written for tubes. MikesRadioRepair 34. Receives good, power out good 5w, but No modulation. It's a module that was "supposed" to increase your modulation and let your radio 'swing'. How to Peak & Tune CB Radios? [6 Steps] A CB radio is basically a radio system that enables you to communicate with other CB radio holders by transmitting signals via the Amplitude Modulation (AM) mechanism. This technique offers many advantages, such as an excellent square wave response from DC to over 250 KHz. 53v 2. In a standard legal CB set with a 4 watt carrier, you need 12 watts peak power in the modulation amplifiers to get 100% modulation. Join a vibrant community of like-minded individuals and explore the exciting realm of CB radios. Ensure proper power connections, antenna setup, and check for blown fuses or sound problems. The receive works fine. On SSB is there modulation? You should see the meter swinging as you talk. Thanks for watchingLike, subscribe, comment and click on the bell so y Mar 13, 2014 · Now we get to CB. Checked voltage at TR51 and the audio chip, both tested good. 9K subscribers Apr 9, 2017 · Works on all cobra 29 radios, ltd and up. Voltages are as follows for MB3756, front of radio to back on pins 1. Galaxy Radios DX2517 Service Manual Nov 20, 2017 · 2017 DX3 TS: Cobra 29 LTD My CB radio turns on and lights up. 53v 8. com Dec 18, 2008 · Picked up an old Connex 3300HP for cheap. Squelch working as normal. The radio receives and it has a 5 watt carrier but no mod. So transmit is dead. You cannot raise the power output of a CB transmitter, use external amplifiers, or modify the unit internally to increase power. If it isn't, adjust the radio deadkey up or down until you get it somewhere in that range. I have a Cobra 2000 GTL which is working perfectly EXCEPT there is no receive whatsoever. it only had a 390k ohm resistor in it!! Jul 23, 2022 · I had previously posted about other issues with this radio but decided not to resurrect that old thread. Aug 9, 2013 · We started going through the radio making sure everything was tuned up to spec. Just put a new 2003 audio chip in it and the fact that it is modulating means that it's Apr 29, 2025 · The Federal Communications Commission (FCC) mandates specific power limits for CB (Citizens Band) radio transmitters. 6. When you speak into the microphone the AM carrier wave is increased or modulated relative to the level of your voice. A general guide for trouble shooting common CB Radio problems. transmit around 4 1/2w Dead key very good receive on a. Some of these modification technically are nonsensical at least from my perspective that these modulation super tunes and swing mods are claiming from a few parts. Every post I've read about the modulation adjustment tells you to turn vr4 all the way up counter clockwise, problem is my radio has no VR4. I went thru with my FC and have the frequency from the mic pins to the so 239 but no mod with good known mic's. Dec 18, 2008 · BUT no modulation on the meter. After a complete tune up/upgraded final/mosfet/etc, See the attached PDF. Tried with a known working mic too. ANY Thoughts? May 22, 2023 · Most CBs do all the heavy switching inside the radio and the PTT switch is just for signaling. Basically now working Jan 29, 2012 · I can see the towers for both of them. If these two radio stations can produce a loud, clean signal without trashing every electronic device around them then why can't a 4 watt CB radio? Remember, there are much more effective ways to achieve good results from a CB radio without butchering it and creating a splatter box. Dec 15, 2020 · General Lee Radio Problems No Modulation On Low Power & Other Problems Discussion in ' CB Radio Forum ' started by steve53, Dec 15, 2020. I have check most of the transistors PNP and some NPN with no luck finding the problem. capasitors. 8. Faint burnt smell in the radio. But, they're different enough that by the time you've "converted" from one to the other, you've probably replaced more parts than you've re-used. May 4, 2021 · I picked up this cb used with no mic. Thanks for any help Thanks to Ray Byrne of Ireland and Tim Trent of Arizona for helping with the troubleshoot of this radio. As far as my knowledge goes, it's around average. If you don't have a spare that does raise the degree of difficulty a touch. It would receive and transmit a carrier (confirmed with a local 7 miles away) but there was no modulation. The mod needle shudders slightly and just sits there. Low deadkey with huge swing is overmodulated (also bad). Guess that means the finals are ok. Galaxy DX-2547 (no mods other than frequency expansion). Nothing more. Have you ever noticed that if you use the rig in PA, the ALC’s are disconnected? In PA the ALC is defeated. Learn how to get maximum receiver sensitivity, RF transmitter power output, modulation and range from your AM or SSB rig by simple adjustments. Their Sideband radios such as the 146, 148 gtl and 2000 were superb, they were stable and a radio you Aug 10, 2015 · The circuit limits the final voltage to maybe 6 or 8v with no modulation then raises it to the radio supply voltage with modulation. Can some help me with this please? I have looked it over like 100 times looking for something burnt or not connected but everything looks good. The resistor can be replaced with a jumper made of wire or solder, or a resistor of a lower value. rbor nnxjoi bafy quy lalj ccppxn binton gtqltatq phr dnkzbcos