What is the maximum tolerable dBm/mW the 6700 can handle before damage?

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  • Updated 6 years ago
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I am contemplating a pixel tech loop antenna on RX A or RX B and wanted to know how much signal in dBm or mW the 6700 can handle safely. The loop comes with an TX isolator relay but I'd prefer not to use it because of the radio's awesome full duplex abilities. The main antenna is a Carolina Windom 40 with the tip of it pointed towards the loop about 8 feet away. The maximum power I'd ever send out the OCF is 500-600W from a KPA500, but most of the time I'm under 100W. I am struggling with HOA limitations and trying to maximize my RX abilities.
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K6OZY, Elmer

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Posted 6 years ago

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Watts - K4QJZ

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I have the same pixel loop and recommend it but it has a 30 db amp at the antenna which can really add to the signal level. I have mine 30 feet away with 100W and strongly recommend you use the function " relay " to disconnect the antenna. It does two things, it disconnects the power to the antenna amp ( helping to protect the amp) and disconnects the feed line to the radio. The radio may take the significantly amplified signal but based on my professional work experience in communication I would be concerned about the Amp as well as the radio.
Great antenna if local noise in the 160-40M band is an issue, big reduction in noise for me 8-15 db.
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K6OZY, Elmer

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Thank you for the recommendation. I will tread carefully. I just hate the thought of a clicking relay during QSK.
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Graham - KE9H, Employee

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Official Response
The receiver overload level for the Flex-6500 and 6700 receivers is about +8 dBm, which is about S9+80 dB (for Preamps off, or a gain of 0). Above that, data converter overload occurs, and the receiver function is disrupted. Damage should not occur below +20 dBm, at which time other protection, such as reverse power disconnect relays and voltage clamps kick in.

So, if you design your antenna system so that you never see more than +20 dBm, you should be safe. If you keep the levels below, say 0 dBm, you should be able to still receive.

If the input levels go above +20 dBm, the receiver should still self protect, but this is for accidents and incidents, and I would not want to see a system design that routinely triggered or depended on the emergency protection.

--- Graham / KE9H
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K6OZY, Elmer

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Thank you for the detailed explanation. The radio seems to have amazing dynamic range.
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Andrew Russell

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G'day Graham,
I can confirm that +24dBm at 475kHz blocks the Rx on my 6500.
This is 10V pk-pk into 50ohms on my 80m full wave loop.
The other antenna a 160M inverted L with loading for 630M, is very close with 50W input.
Andrew / VK5CV/VK5ZUC