[CQ-Contest] SO2R Hardware Question

[John Geiger]

Hi Rich,

Yes, that is what I am hoping to accomplish and I have found a couple of
different devices to allow this.  Interesting that the 7600 and FTDX5000
have RX in and out jacks since they both already have second receivers in
them.  Guess those jacks are more to use the preamps or something like that.

73 John AF5CC

On Sat, Dec 16, 2017 at 12:58 PM, Richard Ferch <ve3iay at gmail.com> wrote:

> What I believe John wants is quite simple, and relatively straightforward
> to implement, but as far as I can see it has little to do with SO2R.
>
> As I understood it, he wants to be able to listen to two receivers at the
> same time, both connected to the same antenna. Presumably he doesn't have a
> dual-receiver rig, but he wants to approximate the same capability using a
> second transceiver as a second receiver.
>
> One aspect of dual receive is audio routing. The easiest solution to this
> is to use stereo headphones with one receiver routed to each earpiece - a
> stereo to dual mono adapter will do that, or you can make things fancier
> with an audio switching setup where you can choose either or both receivers
> as audio sources.
>
> The more significant aspect is protecting the second receiver against the
> first transceiver's transmitted signal.
>
> Some transceivers (Elecraft K3, Icom 7600, Yaesu FTDX5000, etc.) provide a
> built-in capability to do this, namely RX Ant Out and In connectors. The RX
> Ant Out connector is actually a connection to the main transmit antenna
> through the transceiver's T/R switch. Connect a splitter (or coax tee)
> between the RX Ant Out and RX Ant In connectors and feed the second
> receiver from the other branch of the splitter. You can use an SDR as a
> panadapter/spectrum display this way.
>
> With transceivers that do not provide this capability you should be able to
> do something similar with an external relay, controlled from the first
> transceiver's PTT Out connection (the one used to control an amplifier),
> that will switch the second receiver's antenna connection out of line
> whenever the first transceiver is transmitting. This harks back to the days
> of separate receivers and transmitters. Depending on the degree of
> isolation required and achieved, you might need some additional front-end
> protection for the second receiver. The transmitter also has to have a
> sufficient transmit delay, i.e. PTT has to be asserted a sufficiently long
> time before output begins, to avoid hot switching.
>
> I believe there may be electronic receiver protector devices available that
> can perform a similar function.
>
> This, at least, is how I understood his original question.
>
> 73,
> Rich VE3KI
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