G'morning 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? A couple I have require reversing polarity to switch them back. This is requiring more circuitry and complexity. Are these latching relays necessary? I'm seeing several relays available on ebay. The time spent in transmit is miniscule compared to receive.
73 Bob W7LRD Seattle "if this were easy, everyone would be doing it"
----- Original Message ----- From: w7lrd@comcast.net To: "NW VHF" PNWVHFS@googlegroups.com Cc: "AMSAT-BB" AMSAT-BB@amsat.org Sent: Thursday, January 17, 2008 4:50 PM Subject: [amsat-bb] sequencer switching
G'morning 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 handling capability. 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 necessary?
They are not necessary for your application and in general they are not suitable with standard sequencers and in addition they have higher switching time.
I'm seeing several relays available on ebay. The time spent in transmit is miniscule compared to receive.
73 Bob W7LRD Seattle "if this were easy, everyone would be doing it"
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