Dream Station, SO2R and Antenna Selection

John K3MA

I have pondered this issue for the last year and searched for a clear explanation but I have yet to find one or at least one I understand.

I have a 6600M, TGXL, PGXL SO2R, and Antenna Genius. It is set up and configured as per the Dream Station paper posted by Ken Wells.

I primarily want to use the SO2R and A antenna/B antenna paths to monitor DX on two different bands. Usually, to listen for them to start transmitting and beat the pile up.

Using a real example from this morning.

I have Slice A setup on 28074 using a Hexbeam. Slice A is set to TX and RX on Ant 1 and uses the TGXL to touch up the SWR. If I select TX for this slice all the switching of the station works as expected and a low SWR is seen.

Now I want to monitor a second band. I create Slice B and set it to 14195. I want to use a Doublet for this band and select Ant 2 for TX and RX. It also requires the help of the TGXL to tune the antenna SWR. If I then select TX for this slice the station selections change as expected and a low SWR is seen.

So it appears that each slice individually work fine with all the amplifier, tuner and antennas switching as expected.

Now here is the problem I hear. Depending upon which slice is selected for TX the other slices' receive noise and signal strength changes and in some cases drastically. It sounds like it is now receiving from a different antenna and the signal is attenuated. A check of the Slice antenna selection and the Antenna Genius antenna assignment still show the correct antenna for that slice. This is also easily seen in the waterfall with the noise floor changing.

So let's say I am working stations on Slice A with FT8 nicely and I hear something on the Slice B receiver that I want to work. If I change the TX to slice B all the signals on Slice A go down.

I guess my expectation with having this SO2R system is that selecting TX on one slice would not have had an effect on the receive conditions on the other slice. I would think that would be an issue for any contest operator using such a SO2R setup to look for a multiplier on another band while running stations on the first band. The signal on the hunting band would be attenuated compared to using only a signal band and the multiplier could be missed due to the attenuated signals. Maybe this condition is not seen in a real contest station as they would typically have multiple antenna that are resonant for any of the bands and hence not require the help of the TGXL to tune the antenna. Unfortunately, I live in a HOA and have to make do with antennas I can use on multiple bands.

Is this caused by the PGXL or TGXL not being able to provide the correct matching conditions on the Slice unless it is selected for TX?

Is what I am seeing a normal condition and how do others work around it?

DL4RCE

Hi John, I do not experience what you describe. At one time I had a faulty SO2R module in the TGXL which had to be fixed. Does it also occur when FDX is disabled? But I guess you should open up a Ticket with Flex to let it check.

John K3MA

https://community.flexradio.com/discussion/comment/20608655#Comment_20608655

Thanks Volker. FDX is off and the TGXL was just returned a few days ago after having the SO2R module replaced. I just wanted to check here before putting in a ticket to ensure I was not expecting something that the equipment is not capable of doing or if I had something not configured properly.

DL4RCE

When opening a ticket your system will be checked. Maybe it is just a little set-up error.

Good luck with it.

David Decoons, wo2x

Are you creating Slice B in a separate panadapter?

Dave wo2x

John K3MA

https://community.flexradio.com/discussion/comment/20608666#Comment_20608666

Yes. Dave if you want to join via Anydesk to a desktop view session sometime I would be happy to show you what is going on.

John K3MA

One other thing I just noticed. If I set up the Hexbeam to be bypassed in the tuner on a band. Then I go to operate with the Doublet (needing the tuner) on one band and the Hexbeam (bypassed through the tuner) on another band. The result is that the PGXL only seems to allow for both antenna to be operated through the tuner or both antennas bypassed through the tuner. I was expecting that when I set the Doublet to be the TX antenna the tuner would be in operate and if I then selected the Hexbeam to be the TX antenna then the PGXL would be in Bypass.

John K3MA

I have submitted a help desk ticket in hopes of having someone from Flex view the conditions I am observing and confirm that it is not the expected behavior.