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Diplexer Isolation

Oct 24th 2014, 22:01

wx1s

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
When using a diplexer, is 60 dB enough port to port isolation to prevent front end damage of a multi-band satellite transceiver? I plan to run 100 Watts VHF and 50 Watts UHF. Modes will be CW and SSB. The diplexer will be installed at the radio, and there will be one feed line going out to the antenna.
Oct 26th 2014, 20:13

AA6E

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
The calculation goes like this. You have 100W of RF. That's +50dBm. If you believe your 60 dB number, you should have 50-60 = -10 dBm at the input of your receiver. You'd have to check what is the maximum allowed input for your radio, but it's probably higher than -10 dBm. So *if you believe all this*, you're probably safe.

73 Martin AA6E
Oct 28th 2014, 20:31

wx1s

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Martin,

Thanks for your response. Unfortunately my manual doesn't state what the maximum signal allowed at the radio input can be, so I asked the manufacturer. Tech support didn't give me a number, but assured me that customers have been using duplexers without a problem for years.

Thanks again,

fred WX1S
Oct 29th 2014, 19:10

WB1GCM

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Our ARRL Laboratory limit for signal input is +10 dBm (10 mW). It is considered the highest "safe" signal input for test purposes.

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