Mini Magnum Radio not transmitting after Final Replaced
My buddy had a loose coax on his wife's little wil antenna and blew the final in the radio. I found another final and replaced it and the power input diode that was shot. The radio powers up and the final doesn't heat up like it was doing when he brought to me, however the radio only keys aout a 1/10 of a watt. I checked the pre final and it is fine. What could be causing the non existent transmit power? Bias resistors or is it like a electrolitic is bad??? Also, I cannot find a schematice for this radio to even identify what is what.
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Re: Mini Magnum Radio not transmitting after Final...
Not knowing what kind of equipment you have, its hard to say, but .10 watt? Sounds like the buffer or driver also got involved. Usually you get 1/4-1/2 watt to the driver on a stock radio. I would also check the bias resistors like you suggested. Also check for burnt foil around the final you replaced. Good just be a slightly damaged circuit. Let me know if this helps. Tom
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Radios that transmit require a matched antenna for the frequency of operation. A bad coax line from the radio to the antenna or a faulty antenna that would otherwise destroy the radio may trigger a protection circuit inside the radio to prevent damage. Check the coax, and have someone test your antenna with an SWR meter or directional coupler. Good luck
Possibly an antenna problem. Check your antenna set up. Be certain all connections are tight, and there is no damage or smashed places in your coax. Also check to see you are using the correct antenna for your frequency bandsplit. Depending on the type of antenna your antenna may need to be trimmed to a specific length. Look at the coil at the base of the antenna (black dixie cup shaped device). Check it for corrosion. Shake it, if it rattles, replace it.
Swap your radio with another vehicle's radio and see if the problem stays with the radio. If so, your radio needs service.
There are a variety of reasons for your Spectra to fail to transmit. A few items to check would be: 1) Power to the radio. If enough power is not present, transmit is the first thing to usually fail. 2) Check your hand mic. This is a common failure part on a mobile radio. 3) Check your antenna and connections. Coax ages over time, and is not forgiving of creases or bends. Also, if your antenna stinger has become loose over time, it will effect your transmit.
Beyond the above mentioned items, most anything further would require repair of the component board of the radio.
you have a antenna problem or coax problem the light coming on means your swr reading is too high. find you a cb shop they will adjustyour antenna for around 10.00 bucks... if yourepeatedly talk on it it will burn up your radio...
You may have a bad antenna. What happens is a lot of guys carry their radios around by the antenna, inside the connection to the antenna is weak and can crack at the solder joint, thus opening up the antenna circuit and prevent you from transmitting any power out. Our Motorola hand helds have this problem, they are weak at the antenna connector and guys swing them around by the antenna end up breaking them. Your next problem is that if the radios have been used often enough with a faulty antenna circuit, your final amplifiers are probably toast from transmitting into an open antenna circuit, causing all the power to be reflected back into the radio and burning out the final amplifiers
Check your antenna connections and coax for loose connections or damage. Also check your hand mic. See if the problem disappears if you turn on the radio without the mic attached. The two most common problems with a mobile radio are antenna and mic problems.
If you feel these are in order, it would be wise to have a tech look at the radio.
It is not typical but neither is there a problem with the radio.
Transmit Power output is loosely dependent on the:
1. Frequency or channel you are transmitting. Normally, Marine Band VHF are calibrated for max (25 in your radio) at Ch16 or 156.800Mhz;
2. If the SWR of the antenna is not a flat 1.0, power tends to go down;
3. After some time, the TX side of the radio needs to be re-calibrated;
4. Power Supply - some radios will push max output only when powered with 13.8 and tends to go down when used with 12 volts.
Hope this be of some help/idea. Post back should you need additional information.
Good luck and kind regards.