Question about Cobra 148 GTL 120-Channels Base CB Radio

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Cobra 2000gtl no sound comeing out but will talk on am and ssb can you help

Everyone tells me that they can hear me good on am and ssb very good but i can;t get any sound comeing out of it or no incomeing sight on the meter the meter don;t not move any even if i key a other cb up sitting right next to it could you tell me what to look for or what to change to fix this i really do like my cobra 2000 and would like to see it playing on the air again thanks for any help

Posted by caveman2007 on

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Anonymous

Because you have transmit, more than likely your audio section is OK as much of it is shared with the receive side. A final test of the audio section is to check out the PA function. If it works most of the audio section has been tested.

The signals for the meter movement and receiver sound are developed in the audio detector circuit (diodes D21 and D22) just past the I.F. stages (Transistors TR16, TR17, and TR18). I have seen these diodes fail. They are frail little guys, but are inexpensive. I would recommend replacing them first. Pay particuliar attention to which way the band on the diode is positioned and limit your soldering time. If that does'nt rectify the problem, (no pun intended) you can look at the transitors.
By the way, MOVE that second test radio farther away or you could overload the front end of your Cobra creating even more problems. Good Luck, 302

Posted on Nov 29, 2007

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Yaesu 857D very poor audio out on SSB.


Dbl check your swr in am mode.. Ch your ssb power and mic gain default is 50 on both on hf .. If you use the mh-59 you will need to reduce the mic gain to 35 and it needs to be set for remote mic in the menu. Also the ssb needs to be set 2.5k wide with the ssb carrier zeroed both tx and rx

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Ihave a gargeled recive sound


Check the position of the mode selector switch. You may be receiving a SSB (single side band) transmission that is not on the exact same frequency as you or, your radio is in AM or FM mode. You will need to select either USB or LSB (upper or lower side band) and vary the clarifier knob until the sound becomes intelligible. If the sound does not become clear, try the other side band and repeat varying the clarifier knob.

Conversely, if you are in USB or LSB mode and there is a transmission on AM or FM, it will have the same garbled sound. Try changing the mode to AM and the FM. If it does not become clear, it is likely a SSB transmission and you are not on the exact same frequency of the transmission you are hearing. Vary the clarifier knob until it becomes clear - or change to the other side band if needed and try the clairfier again.

The short story is that you must be in the same mode and on the same exact frequency. When in AM or FM, this is less of a problem as these are much more wide banded signals than SSB signals.

The 2990 is really a 50 watt 10 meter amateur radio - but is geared to CBer's as it is easily modified to work in the CB frequency range and the so called "free band" between USA's CB (11 meters) and worldwide amateur 10 meter bands. Be careful transmitting this radio on CB frequencies as it violates FCC rules for power output there - and transmitting in the 28MHz - 29.7MHz requires a valid amateur radio license. Fifty watts on ham frequencies is tiny compared to the 1500 watts permitted. Why not get your ham license (here's how) and leave the "Chicken Band" (and all it entails) behind. You won't miss it!

I hope this helps and good luck!

Apr 12, 2012 | Cobra Radio Communications

1 Answer

Galaxy DX 959. SSB doesn't seem to work. The power meter needle moves in AM but not in SSB. I tried adjusting the bias between test points 7 & 9 to 50 mA via VR12, but can only get it down to 90...


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Jun 19, 2011 | Galaxy Radios DX-959 40-Channels Base CB...

1 Answer

Please explain a 10 meter am/fm radio


Okay.

You do set this up like a regular CB. The meters refers to how long the waves are. CB is 11 meters. So its very close. The antenna woud be tuneds slightly shorter. Use the SWR meter in the radio to calibrate just like you would a normal cb.

Now for the ABCDEF knob. each letter is 40 channels in the band. So A would be 1 - 40 channels, then B would be the next 1 - 40 channel frequencies. You use the frequency counter in the radio(providing that model has one) to tell what channel you are on.

Here is some info one the frequencies in the band.

Now for AM and FM. this is the type of modulation you are using for transmit and receive.

CB transmits on AM or SSB. Amplitude modulation or Single side band. Most CB radios only have AM. But some also have SSB. None will have FM.

FM is frequency modulation.

10 meter radios can have AM FM SSB and DSB depending on the model and options it comes with.

So your radio has 6 ranges for freqency. each is 40 or 50 channesl. Not sure what model you have. If it has 40 then you have 240 channel freqencies.

with AM and FM, you double that, because you can talk on AM or FM on all the channels. If you are on AM and some one transmits on FM unless they are really close, you will not hear them at all, but if you do with will just be garbbled noise.

Also Am and FM both work a little different with range etc.

Now, you may be able to talk on the CB channels as well. Cb starts at 26.965 MHz and ends at 27.405 MHz. The channels are all .010 MHz appart.

Hope this helps

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2 Answers

How to adjust frequency on transmit??? Galaxy


hELLO THERE
hERE IS SOME MODIFICATIONS FOR THIS RADIO
Galaxy Mods DX 2527 - VR 1....AM/FM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 7....SSB Carrier Balance, VR 8....RF Meter, VR11...Driver Bias, VR12...SSB ALC, VR13...Hi Power, VR14...AMC, VR15...AM Low Power, VR16...SSB Low Power, VC 1....10.240, VC 2....10.240. DX 2517- VR 1....AM/FM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 5....FM Deviation, VR 6....SSB Carrier Balance, VR 7....TX Offset, VR 8....CW Beep Level, VR 9....RF Meter, VR10...Final Bias, VR11...Final Bias, VR12...Driver Bias, VR13...SSB ALC, VR14...AM/FM High Power, VR15...AM Modulation Meter, VR16...AM Modulation, VR17...SSB Power, VR18...AM/FM Low Power, VR601..13.8 Volt Power Supply. DX 22B- VR 1....AM/FM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 7....SSB Carrier Balance, VR 8....RF Meter, VR11...Driver Bias, VR12...SSB ALC, VR13...High Power, VR14...AMC, VR15...AM Low Power, VR16...SSB Low Power, VR21...TX Offset, VC 1....10.240, VC 2....10.240. DX 11B- VR 1....AM/FM S-Meter, VR 2....SSB/CW S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 5.....FM Deviation, VR 7....SSB Carrier Balance, VR 8....RF Meter, VR10...Final Bias, VR11...Driver Bias, VR12...SSB ALC, VR13...AM/FM High Power, VR14...AM Modulation, VR16...CW Tone Level, VR20...Final Bias, VR21...TX Offset, VR601..13.8 Volt Power Supply, VR803..AM/FM Low Power. DX 77HML, DX 88HL, and DX 99V- VR 1....AM/FM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM/FM Squelch Range, VR 5.....FM Deviation, VR 7....SSB Carrier Balance, VR 8....RF Meter, VR10...Final Bias, VR11...Driver Bias, VR12...SSB ALC, VR13...AM/FM High Power, VR14...AM Modulation, VR16...AM/FM Low Power, VR20...Final Bias, VR21...TX Offset.
Unmarked VR in R189..AM/FM Medium Power for DX 77HML only. DX 33HML, DX 44V, DX 55V, DX 66V, and DX 73V- VR 1....AM/FM S-Meter, VR 4....AM/FM Squelch Range, VR 5.....FM Deviation, VR 8....RF Meter, VR12...Low Power AM Modulation, VR13...AM/FM High Power, VR14...High Power AM Modulation, VR16...AM/FM Low Power.
Unmarked VR in R188..AM/FM Medium Power (DX 33HML only)
Unmarked VR in C139..Med Power AM modulation (DX 33HML only) DX 949,DX 959- VR 1....AM S-Meter, VR 2....SSB S-Meter, VR 3....SSB Squelch Range, VR 4....AM Squelch Range, VR 6.....SSB Carrier Balance, VR 7....TX Offset, VR 9....RF Meter, VR10...Final Bias, VR12...Driver Bias, VR13...SSB ALC, VR14...AM High Power, VR15...AM Modulation Meter, VR16...AM Modulation, VR17...SSB Power, VR18...AM Low Power, VC1....10.240. DX 2517 and DX 2527-
Symptom:Buzzing or motorboating sound in either the transmit or receive.
Problem: TR602 is oscillating
Cure: Replace C602 with a .01uF cap {Cap is located in the power supply board}.
RG 66,99,DX2517 Replace Q54 2SB754 60watt 7A with a higher power 2SB817 100 Watt 12A. Derating of this component will cool operation, provide better voltage stability,decrease wobble, allow voltage increase to 14.5 volts comfortably. (replace 10 volt caps in this section of the radio to a minimum of 16 volts before increasing supply voltage to this level)and provide faster swing rise time, Replace Q37 2SA473 to a 2SA1012-0 or ECG153 this will improve the clarity and volume of the modulation and it will also run a lot cooler.

Nov 12, 2009 | Galaxy Radios DX-949 40-Channels Base CB...

1 Answer

I have a galaxy93ttwin turbine that has a modulation prob on ssb


well i hate to tell you this but some cb ******* shop hacked the **** out of you radio and you have been ripped off they probably ripped all the audio limiters out volted the final and put that stupid modulation kit in there. unbeliveable. i hate the cb hacks that give good techs like me a bad name. shame on the hackers. that is why it does not work on sideband.

Jul 07, 2009 | Galaxy Radios DX-93T Base CB Radio

1 Answer

I can't hear.


I am not completely sure i understand whats going on. it seems like it could be a few things because of different parts of the question.

With my CB everyone else can hear me and the signal transmits fine
Good!
I have tested to see that my CB is picking up the signal
how? A meter on your radio should either light up or a needle should swing if you are receiving.
their voices don't play through my mic of my PA
A Mic is a microphone, i think you mean speaker.
Ok this may be the cause of the problem....
Try a couple of these.
First, unplug the PA Speaker, this simple act should make you to be able to hear the incoming signal.
Make sure the CB is on AM or CB not PA
If you can not hear the speaker may be busted or an internal part may be blown. (needing the expertise of a required technician)
If you can here when you do this make sure the speaker is working by plugging it into a computer. (mp3 players will barely put out enough power to make a sound audible) if this works, make sure you plug it into EXT not PA on the back of the radio.

one more thing to check. i dont know what radio you have but try turning it untill you hear static. if its all the way the other way you may not hear anything, also turn up any RX or rec. knobs.

i have limited knowledge about whats going on, but i hope this will help fixya

Jan 05, 2009 | Midland 1001Z 40-Channels Base CB Radio

1 Answer

Magnum S9 10/11 mtr radio


If you're receiving OK on AM & SSB, the likely adjustment would be the FM discriminator coil L5. You can adjust it for maximum noise with no signal applied.

Mar 22, 2008 | Magnum DeltaForce CB Radio

1 Answer

Audio limiter


tintlady, here is the info you requested;
the AM limiter is R 276

These are the variable adjustments inside,and what they control.
VR-1 AM S-METER
VR-2 SSB S-METER
VR-3 SSB SQUELCH RANGE
VR-4 AM SQUELCH RANGE
VR-6 SSB CARRIER BALANCE
VR-7 TX OFFSET
VR-9 RF METER
VR-10 FINAL BIAS
VR-12 DRIVER BIAS
VR-13 SSB ALC
VR-14 AM HIGH POWER
VR-15 AM MODULATION METER
VR-16 AM MODULATION
VR-17 SSB POWER
VR-18 AM LOW POWER
VC1-10.240 MHz Frequency adjustment

Hope this helps you out, let me know,,Mechanic

Jan 20, 2008 | Radio Communications

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