Pages: [1]   Go Down

Author Topic: Using Yaesu FAS-1-4R as a transceiver switch (rather than an antenna switch)  (Read 126 times)

F4GFT

  • Member
  • Posts: 77


I am using an Yaesu FAS-1-4R as a remote antenna switch for many years, and am very happy with the unit. I have another one and wonder if I could use it to switch between two transceivers, with sufficient decoupling to not fry the receiver of the #1 transceiver while sending on #2. I cannot find specs for using this switch as a transceiver switch (rather than an antenna switch). Any experience? I do not run an amplifier, just the stock 100W. If the Yaesu FAS-1-4R is not suitable, what would you recommend for the task?

Andy F4GFT
Logged

WA3SKN

  • Member
  • Posts: 8126

ALL ports are shorted(grounded) until a relay operates... so only one radio could be used at a time.
Will that work with your plans?

-Mike.
Logged

W3PX

  • Posts: 190
    • HomeURL

If you had access to a Nano VNA or could purchase one, you could measure the port to port isolation and know for sure.
Logged
"So, we just went ahead and fixed the glitch" - Bob Slydell

"I’d say in any given week I probably only do about fifteen minutes of real, actual, work" - Peter Gibbons

F4GFT

  • Member
  • Posts: 77


>ALL ports are shorted(grounded) until a relay operates... so only one radio could be used at a time.
>Will that work with your plans?

Yes, I think so. I would like to be able to use the radio with the shorted port on its port#2 for 6m monitoring (the 6m antenna is some 35ft away from the HF antennas), but that's another story.

>If you had access to a Nano VNA or could purchase one, you could measure the port to port >isolation and know for sure.

I can get my hands on one; I did not know these things also measured isolation. Is it safe to assume that at least 60dB are required? One of the radios is a FT-950; I heard the FT-2000 had a somewhat fragile input stage. The other is a TS-930, no idea about the ruggedness of its receiver.

Andy F4GFT
Logged

W3PX

  • Posts: 190
    • HomeURL


I can get my hands on one; I did not know these things also measured isolation. Is it safe to assume that at least 60dB are required? One of the radios is a FT-950; I heard the FT-2000 had a somewhat fragile input stage. The other is a TS-930, no idea about the ruggedness of its receiver.

Andy F4GFT

To test the port-to-port isolation of your switch, you would use the Nano VNA to measure S21, transmission between the two test ports.

A 100W signal (+50 dBm) present at one port of the antenna switch, with a port to port isolation of 60 dB, would present a -10 dBm signal at the second port.

Check the receiver maximum input level spec for your radios to be sure.

73 Frank W3PX
Logged
"So, we just went ahead and fixed the glitch" - Bob Slydell

"I’d say in any given week I probably only do about fifteen minutes of real, actual, work" - Peter Gibbons
Pages: [1]   Go Up