[Moon-Net] LNA Relay

James C jabeco at gmail.com
Sat Sep 28 19:26:51 CEST 2019


FWIW,  Besides the additional protection an iso relay provides, it also
ensures your LNA is always looking at a 50ohm impedance to deter self
oscillation. Something to think about anyway,. GL, 73 .-James K7KQA

On Sat, Sep 28, 2019 at 9:32 AM Stephen Hanselman via Moon-net <
moon-net at mailman.pe1itr.com> wrote:

> 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
>
>
> ----------
>
> _______________________________________________
> Moon-Net posting and subscription instructions are at
> http://www.nlsa.com/nets/moon-net-help.html
>
> _______________________________________________
> Moon-Net posting and subscription instructions are at
> http://www.nlsa.com/nets/moon-net-help.html
>
> _______________________________________________
> Moon-Net posting and subscription instructions are at
> http://www.nlsa.com/nets/moon-net-help.html
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.pe1itr.com/pipermail/moon-net/attachments/20190928/7a311dd1/attachment-0001.html>


More information about the Moon-net mailing list