Question about Garmin VHF-725 2-Way Radio

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VHF transmit power

I have a VHF marine radio with 25W of transmit power. When I connect an SWR meter and key the mic the meter reads 16 to 18W. Is this typical or does it indicate a problem with the radio? Thanks.

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Re: VHF transmit power

Thank you for the info...very helpful! I guess the real test is if I can be heard by my fishing buddies. Thanks again.

Posted on Oct 05, 2007

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Re: VHF transmit power

Hi, 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.

Posted on Oct 04, 2007

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It could be a self-protection circuit activating.

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Initially, pls check/clean your antenna, mount, coaxial cable, RF connector, power leads, grounding straps.

Based on your post description, a couple of ideas:
1. Since you receive OK, chances are the antenna/cable is good. You verify though with an SWR meter;
2. Since TX light comes on, looks like the mic, PTT and coiled cord are all OK;
3. All else works but no one can hear you, you have no power output. Use an RF wattmeter with dummy load to verify that you are pushing at least 25 watts. In the absence of a power meter, the SWR would also do or even an indication of a significant current flow to the radio ( use an inline ammeter) would indicate power.
As you will note, some specialized instruments are needed. Perhaps your best bet would be to seek the services of a qualified communications technician. TMore often it is the finals or power pack that fails resulting in no TX. In some cases, it is either the RF diode or the power regulator that causes no TX. It may also be worth your while to do a full check over of your antenna system.

Hope this be of some help. Pls post back how things turns up or should you need additional information.

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