[amsat-bb] Re: sequencer switching
domenico.i8cvs at tin.it
Thu Jan 17 08:54:43 PST 2008
----- Original Message -----
From: <w7lrd at comcast.net>
To: "NW VHF" <PNWVHFS at googlegroups.com>
Cc: "AMSAT-BB" <AMSAT-BB at amsat.org>
Sent: Thursday, January 17, 2008 4:50 PM
Subject: [amsat-bb] sequencer switching
> My 1.2Ghz system is progressing nicely. I am currently working on a
> sequencer for "switching around" my amp. I have several good quality coax
> relays. Are some preferred over others?
Hi Bob, W7LRD
Use coax relays with N connectors and the greater isolation in dB between
RX/TX ports and if you don't have this data also called "cross-talk" you can
measure it on spectrum analyser.
Also use relays with the shorter switching time and the higher power
Relays with high isolation between ports have all N connectors fitted in
line in a brass block and relays with very poor isolation have connectors
fitted in a configuration similar to a hammer.
> A couple I have require reversing polarity to switch them back. This is
> requiring more circuitry and complexity. Are these latching relays
They are not necessary for your application and in general they are not
suitable with standard sequencers and in addition they have higher
> I'm seeing several relays available on ebay.
> The time spent in transmit is miniscule compared to receive.
> 73 Bob W7LRD
> "if this were easy, everyone would be doing it"
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