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Antenna power limits

Sep 26th 2012, 01:34

gravero69

Joined: Dec 30th 2011, 05:35
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Total Posts: 0
What is the best way to determine how much power a homebrew antenna or one of unknown specifications can handle ?
Sep 26th 2012, 17:30

WB1GCM

Joined: Apr 4th 1998, 00:00
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Total Posts: 0
Increase power slowly and watch for a slow but gradual increase of SWR is one way. The other involves heat, which may not be east to measure, but can be felt just after RF power s removed from the antenna.

Perhaps another member has a better answer....
Sep 26th 2012, 22:42

gravero69

Joined: Dec 30th 2011, 05:35
Total Topics: 0
Total Posts: 0
The reason I am wondering is I am building a go kit with a Yeasu ft1500m. I want to use a telescoping antenna I bought but it doesn't have a power rating. So if I turn up the power and read it with a IR thermometer, when it starts to heat up that is the limit? Thanks
Sep 27th 2012, 18:24

AA6E

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
It's hard to give good advice here without seeing a picture. Some antennas are designed for reception only. They would use rather small parts, and they may or may not be resonant at your frequency. So don't use a "receive" antenna. A transmit antenna will often (not always) be resonant on the band you want, and parts (wire size, insulation, capacitors, etc.) will be sized according to your power level. Commercial TX antennas will generally handle 100W and often they will claim up to 1.5 or 2 kW. If you operate off resonance (e.g., with an antenna tuner), the peak voltages and currents are likely to rise significantly, so you need heavier duty components that when operating at resonance.

Good luck, 73
Martin AA6E
Sep 28th 2012, 01:25

gravero69

Joined: Dec 30th 2011, 05:35
Total Topics: 0
Total Posts: 0
The antenna I want to use is a base loaded HT antenna I am sure it will handle 5w but I need to send data at a higher wattage. So duty cycle is also something I need to consider. Maybe I should just use my mobile antenna. Thanks everyone KB9YNC Bob

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