As confirmation this a mobile hand held transmit/receiver radio with a 3"X 1-1/2" medal box for the antenna and power supply connections.
The unit does not transmit but receives fine. The SWR is okay.
Trouble shooting suggestions would be appreciated.
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Re: Maxon Model MCB10A
In order to test this unit you will need a power meter with a dummy load. connect the power meter and turn on the unit, key the microphone and look at the power meter it should have a reading of < 4 watts PEP unmodulated and = 4 watts PEP modulated.
If you do not have this reading the RF transmitter in the CB might be malfunctioning. You will need a RF generator, a power meter with dummy load, oscilloscope and a multimeter to troubleshoot this problem with. If you do not have or do not know what this equipment is or how it works, please take your unit to a CB repair shop.
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Maybe its not transmitting because a Final Transistor has blown. Check to see if it receives well, change antennas,microphone...get a meter to measure SWR/POWER out. If it don't transmit or receive it may be seriously damaged. A final only cost several dollars if you know how to solder one in place. Its always like 2SC2078(Radio Shack carries them) it has 3 prongs to be soldered on the board with a heatsink and screwed to back with a ceramic insulator and heat glue. Swr over 2.1 will cause transmitter damage. Bad antennas,lightning may cause these problems. Get an antenna factory tuned at near 1.5 for 27mhz.Wilson 1000's,K40,Antron A99(18 ft.base) are good antennas.Look at www.copperelectronics.com for radio supplies,antennas and new radios.
Try asking any onrt CB'ers if they can hear you at all.
Could be 2 things -
#1 - you are really too close.
#2 - you've blown the output stage of your rig by keying the mic without an aerial fitted.
- This is very common, and most repair centres are used to dealing with this.
If you are up to electronic repair, it's possible to DIY repair.
Could also be an antenna mismatch or fault.
I had the same (squealing) problem on transmit with the Midland 1001Z
when I used it indoors as a base unit. The problem was my power
supply: it broke into oscillation when drawing more than 150 mA at
13.8V. The 1001Z draws about 150 mA on Receive, and much more (but
only about 900 mA) on Transmit. If using the 1001Z as a base unit, I
suggest you power it with a fully-charged car battery indoors, or test
your power supply to check if it can't supply the required 1 Amp,
approx., on Transmit. It's a GREAT radio, just give it a good power
supply. My power supply was defective out of the box, but now I have a
good one and get great reports on signal strength and audio quality.
Remarkable, for the low price and 3 year warranty. Good luck!
I believe that that might be your voltage regulator heating up. This means that there is an internal short in the system. To tesat this properly you will need a 12V power supply, a multimeter, the specifications, and a dummy load antenna.
1) take the cover off of the CB.
2) turn the multimeter on DC current and connect it in series with the red power lead of the CB and connect the red to the + of the power supply. then connect the black lead to the - of the power supply
3) look at the specifications and record the current drain when the unit is receiving not transmitting (write this down), Then power up the CB and record the current drain. If it is high it denotes a short circuit, if it is low then there is an open.
3) look for smoke comming from the rear of the CB this will tell you what component is heating up, locate it on the schematic and see wheat the problem is.
4) replace the bad components
I hope this helps,
Make sure you run the CB directly to the battery. What you are hearing is the alternator whining. Even then sometimes a low pass filter may be necessary. Make sure the chassis of your CB is grounded with a copper braid strap too.
Several things can cause poor reception. I have a few questions for you.
1. Have you tried measuring your SWR (standing wave ratio)? This helps give you an idea how well your transmission line and antenna are working.
2. Is this radio being used as a base or mobile? Do you have proper grounding on the antenna?
3. Pressing the mic button and seeing the radio indicate "transmit" does not always mean you are transmitting at full rated power. Have you tried transmitting through a wattmetter into a dummy load?
4. If the transmission line is good and the antenna is good, then I would suspect that something may be wrond with the receiver's front-end (sensitivity).
Receiver sensitivity can be checked by using a RF signal generator. Unfortunately you'll have to take the unit to a repair shop to have that checked. Try the other things I mentioned above. Let me know what you find and we'll go from there.