Cross SCU transmit / receive on 6700

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In reading the manual it states that the RXA is physically connected with SCU-1 and RXB is physically attached to SCU-2.

The SSDR Software manual further states the following:

Each SCU on the FLEX-6700 has the option of a dedicated receive only antenna designated RX A and RX B respectively. These inputs are hard wired to their respective SCU and may not be switched between SCUs. Note that this does not preclude using RX A with ANT2 or RX B with ANT1.

What are the practical implications of cross connecting ANT and RX antennas across SCUs? If I have slice A configured to transmit on SCU 1 (ANT 1?) and receive on RX B; and if I also have slice B configured to transmit on SCU 2 (ANT 2) and receive on RX A; won't there be a problem when I transmit on one slice blocking the other slice or am I am misunderstanding something (likely)?


- Bob, W1RE
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Posted 5 years ago

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Photo of Steve - N5AC

Steve - N5AC, VP Engineering / CTO

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Official Response

I'll try to answer your question. There are two SCUs in the FLEX-6700 which only have to do with receive. There is a single exciter and a single PA. The exciter may be sent directly out the XVTR port and the PA power must exit the radio at either ANT1 or ANT2. If ANT1 is on the first SCU, ANT2 is available for the other SCU and vice-versa. You do not transmit on an SCU -- the SCUs are receive devices. In the v1.0 software, you should be able to listen anywhere and transmit anywhere that it is allowed (can't transmit on RXA or RXB). If you want to transmit on an antenna that is being used for another receiver, the radio will "steal" the antenna during the transmit cycle and the receiver won't be useful for receive while you are transmitting.

If you are a CW operator, it is important to take note of when QSK works and when it doesn't. If you are in a situation where the radio is forced to flip relays to transmit, QSK is not going to work. We have gone to great lengths to optimize the antenna system and attempt to figure out a way to make your particular selections work best. We created a number of rules that work to favor the best operational conditions and the hardware is capable of a lot. There are around 1,000 scenarios the radio checks to determine the best setup for you before making a decision. I think that you will find that the radio lets you do a lot of things that other radios will not allow. In short, if you look at the diagram that has been sent out with the antenna connections and there is a way to connect the system in a way you want, the radio will figure out how to do it. We invested literally hundreds of hours designing a custom algorithm to optimize the antenna connections and we feel this is a key benefit of SmartSDR.

We have added even more scenarios into the system in the last week that increase QSK capabilities of the radio and to make switching antennas more predictable. We will be making this available in the future, probably in a month to six weeks after it has been adequately tested.

Does this help?