Question about Cobra 19 DX III 40-Channels Base CB Radio

1 Answer

President mckinly ssb/am model with mb8719 pll chip.

Fault finding need help..transmitt carier on am normal 4 watts no modulation on am and no modulation on ssb usb/lsb.receive is alright.checked mic insert -inside mic etc and other end mic plug all ok their.

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  • ric adam Aug 03, 2007

    fuyt back .found predriver 2sc1906 was blown replaced with 2sc1966.final ok.noticed now that the final and driver had 13 volts readings on the base .when switching mode switch am should read 5.50 volts when switch mode switch usb/lsb should read 13.75 volts.checking tr41 dc reg transister also tr42dc reg transister end of press i will be back ......

  • ric adam Aug 03, 2007

    fuyt back tonight 11.20pm been in the garage working on the cb radio put back ic6 found that i could hear my modulation my voice on all modes lsb/usb/am connected another cb radio besides the president radio .mod was low not even moving the needle but i could hear myself looked inside cb again from the mic gain control 2 wires going into the amp stage tr 29 was a bc 458 this did not look right and while touching the legs with my fingers my modulation increased and the watt meter started too peek up.took out tr29 and replaced with a bc945 and wow modulation now on all mode lsb/usb/am.same probem with another cb cobra 148 my friend wanted fixed.my other email is grantmb8719@yahoo.com.au.under cobra cb radios .

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It looks like you had some loose connections in that CB. you may want to also check for other cold solder joints throughout the units and touch them up with some solder. Might I suggest you use a desoldering tool and then just add new solder to the connection.

Posted on Sep 05, 2007

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My hr2600 shows error 3 when it is keyed up and does not transmit


0 = Transmitter Timeout timer has timed-out
1 = Transmit Frequency is lower than TX Lockout Lower Limit
2 = Transmit Frequency is greater than TX Lockout Higher Limit
3 = Phase-locked-loop (PLL) won't lock at this transmit frequency
4 = PLL is intermittently coming out of lock during transmit
*If your radio displays error 3 or 4, don't keep trying to transmit on this frequency. The cause of the problem could be low power supply voltage to the radio or the radio's VCO loop needs adjustment. Refer to a qualified technician for service. Contact the installer of the chip first. If, however, you installed the chip yourself, contact a qualified technician for service.

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How do i adjust the sideband


Instructions

Connect one end of your coaxial cable to the output port on your SSB Transmitter. Connect the other end of the cable to the coaxial input port on your RF demodulator.

Connect one end of your 1/4 inch audio cable to the audio output port on your RF modulator. Connect the other end of the audio cable to the audio input jack on your amplifier.

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President what? Madison, Lincoln etc.

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Just want to know if i should use my ll203 amp in am or ssb mode when running with a cobra CB radio?


What radio?? Does it have single side band(SSB)? If not, then don't use SSB.

AM - amplitude modulation
SSB - single side band.

If you have SSB, there would be a switch on it to transmit in SSB. If not, it is AM only.

Second, Has this radio been worked on to be able to run on an amp? If not, you will blow the amp.

A CB radio transmits dead keys with 4 watts of power, and transmits with 4 watts of audio.

a 4 watt dead key is too much for a linear amp. You will smoke the transistors. Also, 4 watts of audio is not enough to drive it properly. You won't get full power.

The dead key needs to be around 2 to 2 -1/2 watts,or what ever makes the linear dead key half its peak wattage., and the modulation (audio) turned up all the way.

It doesn't sound like you know too much about CB radio's. Not a big deal, you can learn. For right now you may want to take it to a cb shop and tell them you want a peak and tune, and set up to run a linear.

You can find CB shops usually at truck stops. Some area's they are other places. Check the internet for local shops.

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Cobrba 148 gtl TX


Thanks sharcnet i just going through the steps in my head trying to figure out what I would do if it was on my bench ..Between the two of us we'll figure it out!!!..... Dean

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