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ICOM Help

Old 05-20-2008, 06:15 AM
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Default ICOM Help

What is the best way to troule shoot A Icom VHF?
My lower Icom Works Fine the upper doesn't seem to transmit or receive. It does pick up the WX channel fine The both have Digital antennas about 2 years old
Thanks
Tim
Old 05-20-2008, 07:25 AM
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Default RE: ICOM Help

the edge - 5/20/2008 9:15 AM

What is the best way to troule shoot A Icom VHF?
My lower Icom Works Fine the upper doesn't seem to transmit or receive. It does pick up the WX channel fine The both have Digital antennas about 2 years old
Thanks
Tim
If it's "picking up the WX channel fine", it is receiving.

Since you have two VHF radios, the easiest first troubleshooting step is to switch them. This will tell you if the problem is in the radio or somewhere else (power and ground wiring or antenna). If the problem is in the radio, the choice is to have it repaired or replace it. If not, check your wiring or antenna.
Old 05-20-2008, 12:09 PM
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Default RE: ICOM Help

Swap the radios and try to X-mit on both 5w and 25 watt.

I'd also monitor the 12volts at the upper station while X-mitting. (DVM,digital volt meter across the +12v and ground buss bar)

VHF's draw a LOT more current during X-mitt versus receiving.

If the upper voltage drops below 11.8 or so, the raido could shut down for protection.

Old 05-20-2008, 05:43 PM
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Default RE: ICOM Help

Considering the Wx is loud and clear does this eliminate a problem with the antenna
Old 05-20-2008, 05:57 PM
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Default RE: ICOM Help

the edge - 5/20/2008 8:43 PM

Considering the Wx is loud and clear does this eliminate a problem with the antenna
No, a radio will receive fairly well with just any old piece of wire as an antenna. Not transmit worth a darn though.

Swap the radios like I suggested above.
Old 05-20-2008, 08:08 PM
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Default Re: ICOM Help

You need to get a decent power / SWR meter. This is the only way to check a radio.

The power meter will show you forward and reflected power. If the radio puts out less than 25 watts at high power, there is a problem. And when I say "less than 25 watts" I mean A LOT less. It will be instantly obvious.

Reflected power is the power that is not radiated out of the antenna. You will always have some reflected power - but you want this to be as low as possible.

If you are showing 25 watts forward and 10 reflected, you are going to kill your radio. The antenna system is bad.

SWR is a ratio of forward to reflected power. You want SWR to be as low was possible, but as long as it is under 1.7 you are OK. Under 1.5 is better. If you are over 1,7 but under 2.0 then you are in the yellow zone. Something is not right, but you can use the radio. Over 2.0 and you will damage the radio by transmitting.

Otherwise, you are just guessing. Just because you have a good signal on the weather channels does not mean your antenna is transmitting properly. If you can not see RF energy then you really do not know if your system is working.

Ham radio supply places have good meters. That thing sold at marine stores (Shakespeare thing) is a waste of money. I got one that looked like it and it was garbage.
Old 05-21-2008, 02:42 AM
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Default RE: ICOM Help

Thanks Guys
Old 05-21-2008, 06:35 AM
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Default Re: ICOM Help

Lazy_Iguana--

Very good troubleshooting help. Nicely done!

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