[Moon-Net] LNA Relay

Stephen Hanselman eme at kc4sw.com
Sat Sep 28 18:27:28 CEST 2019


Vlada,
Are you suggesting that an isolation relay is not needed on a septum feed?  That would make my 1296 system simpler, but I’m a bit worried about my LNA


73's
 
Stephen Hanselman, KC4SW


Sent from my iPad

> On Sep 27, 2019, at 02:12, vlada via Moon-net <moon-net at mailman.pe1itr.com> wrote:
> 
> Hi Voja,
> as regards LNA input protection, the transfer relay behave actually in the same way as a single port relay.
> So, the level of protection just depends on the isolation of the particular relay and proper function of the sequencer or similar function circuitry.
> Additional relay at LNA input is almost necessary in case of separate but close RX/TX feeds (like septum feed) with limited isolation in-between.
> Optionally, if the relay isolation is insufficient or you are looking for a secured protection, you could use an additional protection directly on LNA input either outside or inside (like a power limiter used e.g. in spectrum analyzers or an antiparalel vhf Schottky diodes etc.).
> However, al these units will obviously somehow (more or less) decrease the noise performance of LNA. 
> 73, Vlada
> OK1KIR 
>  
>  
> ______________________________________________________________
> > Od: "Vojislav Bandobranski via Moon-net" <moon-net at mailman.pe1itr.com>
> > Komu: "Moon-Net" <moon-net at mailman.pe1itr.com>
> > Datum: 26.09.2019 21:39
> > Předmět: [Moon-Net] LNA Relay
> >
> Hi,
> does anyone have experience with using a transfer rf switch (with 4 connectors) in LNA?
> Is it necessary to add another relay in front of LNA input for insulation?
> I mean simple rx/tx transition.
> 
> -- 
> 73 de Voja/YU7C
> 
> 
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