[Moon-Net] LNA Relay
donhawbaker at outlook.com
Sun Sep 29 19:16:55 CEST 2019
That is interesting and something to consider. Not hard to implement for testing. But in addition to parasitic capacitance I think you would also have parasitic inductance, so even a short is not an RF short. It would look like a tapped inductor maybe.
On Sep 29, 2019 at 7:45 AM, <Vladimír Petržílka via Moon-net<mailto:moon-net at mailman.pe1itr.com>> wrote:
Just short note: If the LNA is not potentially unstable, consider as well as
this solution http://www.ok2kkw.com/xyz/isolation_relay.png Of course, two
ports on the septum feed is another issue and additional isolation
significantly helps on it. But remind please security of the LNA in case of
some dirt or water in a septum feed.
From: Don Hawbaker <donhawbaker at outlook.com>
To: James C <jabeco at gmail.com>
Cc: Stephen Hanselman <eme at kc4sw.com>, Moon-Net
<moon-net at mailman.pe1itr.com>
Subject: Re: [Moon-Net] LNA Relay
Just off the top of my head, I think you can get only 20 to 30 db isolation
out of a septum feed.
If you are transmitting plus 53 db or more, you LNA is going to get hit with
23 to 33 dbm. As I recall, they don?t like more than about zero dbm long
term, so you would need an isolation relay.
But like I said, these are numbers just off the top of my head. You can
Google and find the exact numbers.
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