Re: IC-705 antenna switch from band


If your goal is to simply switch between a single multi-band HF antenna and a dual band VHF/UHF antenna, the losses of a single duplexer could be easily overcome by using higher-gain antennas or lower-loss feed line. A single duplexer has very minimal losses, for example, this Diamond duplexer has about 0.2 dB signal loss maximum:

If you decide to employ a CI-V interface, a band switch and antenna relays, you will incur a significant expense ($200?) and still have signal loss (no switch I'm aware of has NO loss). For example, this popular Ameritron RCS-4 antenna switch has 0.1 dB loss at 3.0 MHz:

Don't like MFJ/Ameritron? How about this SSB Engineering part, which is better suited for applications that include both HF and UHF band signals? It has a specified 0.15 dB loss/attenuation:

I like the low cost ($75?), simple, duplexer option for remote operation, it requires zero interaction by the operator, and can be placed anywhere along the feed line, potentially saving on feed line expenses.

My advice, take another look at the losses involved - you may find the popular concern about loss to not be nearly as bad as others suggest.

Final note - even a simple, mechanical coax switch - which would be impractical for a remote setup -has about a 0.12 dB insertion loss:

Daiwa CS-201A 2 Position Coax Switch

It looks like the only way to avoid signal loss is to manually switch coax connectors as you switch bands.

Ken, N2VIP

On Jan 18, 2022, at 08:16, Mark Kyle <kylecom@...> wrote:

Hi Richard.
I have been looking at the CT-17 BT6 interface but not sure if it will do what I want..maybe you have another idea or even better something already done . I am setting up my 705 as a remote station. It will be done with the new Mac software that DL2YMR has made that uses the wifi in the 705 as the network link

I want to be able to change antennas via a remote switch at the remote site. so when on the HF bands I can be on a HF antenna and when on VHF to be on a VHF antenna and the same for UHF. Each will also have a linear amp on them for the correct band.
Others have said to use a combination of duplexers but that introduces too many losses. It would be better to use a relay based system. The relays of course only need to be small RF ones due to the 705 power

Mark  VK4KZK also VK4OI

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