SCU still active when I transmit??

Mike Steventon

Hi.

Ordinarily I select Ant1 to receive and Ant1 to transmit, and am happy and re-assured that my tx mode breaks the receive signal to the SCU.

I have noticed that if I choose to select Rx A (or Rx B), when I go into transmit, my display continues to show the transmitted signal, which is obviously being picked up by my other antenna (inputted at Rx A). It is quite alarming as you can imagine. There shows a massive signal on the panafall display. Is there any way to have the RX A antenna signal to be killed off, as per using Ant1, when I transmit? Or have I missed something in the user manual?

Using 6600M and SmartSDR for Mac.

Your thoughts, please.

Mike. G4GWH

Mike-VA3MW

@Mike Steventon

This is normal and while it looks bad, the radio can handle it.

You can make sure the FDX is turned off so that you don't see it and that will make you feel better.

You may be surprised to know that most HF Radios (if not all) do not ground their antennas while in TX. They are designed to handle the RF voltages they receive by bleeding them to the ground once they get to a certain voltage.

The SCU front end in all our radios is pretty well protected.

73

KD0RC

To add to Mike's response, here is a link to the Full Duplex Power Calculation Worksheet.

https://www.flexradio.com/documentation/flex-6000-fdx-power-calculation-worksheet/

This is only important if you are running Full Duplex (FDX) or multiple transmitters with antennas in close proximity. This is most applicable to contest stations, but filling out the worksheet may allay your fears of damaging your radio when you enter the parameters of your station.

I think you will be pleasantly surprised at how much these radios will tolerate (especially the 6600 with its 7th order bandpass filters on the contest bands).

Mike Steventon

Thank you very much for your replies. Well, you learn something new every day! I will be happy with the display from now on, knowing that the SCU is so tolerant. I am not quite into Full Duplex just yet, but thanks for the calculator info. I think I will be just fine with my layout.

Cheers both.

Mike.