6600 setup for SO2R with N1MM+ Mutes RX slice when TX slice Transmits

Lawrence Libsch

Carefully followed the How To Guide for "Setup for SO2R Mode with a Flex -6700 and N1MM+" by KE5DTO and K9CT. Set the Flex for RTTY instead of the SSB that results from the Guide. Had a first try with SO2R for CQ WW WPX RTTY this weekend.

Initiating transmit in one slice caused receive to be muted in the other slice. So what I got was actually less than SO2V because the RX slice stayed muted after the TX slice finished transmission. Yes I set Full Duplex mode on the Flex and yes I configured N1MM+ for SO2R.

I was using 1 kW with a vertical for 40M and a dipole for 20M about 60 ft apart.

Can you explain why the RX was muted and how to achieve true SO2R?

K4KGG, Larry

KD0RC

Hi Larry, the second receiver needs to be on a different antenna. Since you have the 6600, you can use the other SCU or one of the RX connectors. The second slice on the same SCU won't work.

Lawrence Libsch

Hi Len,

Thanks for your reply. I'll have to look up how to get the antennas using different SCUs for the different slices. I'll be relying on the 6600 band pass filters to protect the 6600. Will they be able to do this? The receive path to the radio passes thru my KPA1500. Do I need band pass filters for it? Really appreciate your help.

Larry, K4KGG

KD0RC

Hi Larry, I am not sure where I saw it, but there is a published set of specs for using a separate antenna in Full Duplex. There are guidelines based on transmit power and antenna orientation and proximity. The 6600 has 7th order filters on the contest bands, so they have pretty good out of band attenuation. You would want to be sure that your second RX is on a different (contest) band to be sure that the filter is in play. I will post a link if I find the document with this info in it.

Lawrence Libsch

Hi Len,

I found some great info on SCUs, antennas, and slices using the Community search. It's clear that as you wrote if the antennas were using different antenna jacks, they would be using different SCUs. I could do that running barefoot. Perhaps that's what to try next.

But my wire antennas need more power. For that I'd need the PGXL, or some kind of frequency sensing switch to allow my existing amp to connect to the proper Ant jack for the transmitting radio. Or I'd need two amps. I know the PGXL is made for this but it's an expensive solution for a station with modest antennas.

If you have some thoughts about a switch, I'd like them. Else, It's time for some experiments barefoot and perhaps with a second smaller amp on the shelf that's looking for something to do.

Thanks again for sharing your time and knowledge with me.

K4KGG, Larry

Lawrence Libsch

Hi Len,

I think we crossed replies. I would love to see that article if you find it. I don't want to damage my 6600 or my amps.

K4KGG, Larry

KD0RC

Fount it! Search Documentation for FDX:

FLEX-6000 Full Duplex Power Calculation Worksheet – FlexRadio

KD0RC

You are very welcome! Hopefully, you will be able to find a set up that allows you to use your amp while in full duplex. The worksheet gives some interesting clues as to the capabilities of the 6600. That 50 dB isolation number for the contest bands is really something!

Lawrence Libsch

Hi Steve,

Thanks for your reply. In my original question I wrote:

"Carefully followed the How To Guide for "Setup for SO2R Mode with a Flex -6700 and N1MM+" by KE5DTO and K9CT. Set the Flex for RTTY instead of the SSB that results from the Guide. Had a first try with SO2R for CQ WW WPX RTTY this weekend.

Initiating transmit in one slice caused receive to be muted in the other slice. So what I got was actually less than SO2V because the RX slice stayed muted after the TX slice finished transmission. Yes I set Full Duplex mode on the Flex and yes I configured N1MM+ for SO2R.

I was using 1 kW with a vertical for 40M and a dipole for 20M about 60 ft apart.

Can you explain why the RX was muted and how to achieve true SO2R?"

I believe the article I followed to setup SO2R was the one you reference. It's excellent, but it's for CW and sideband. I altered it to setup for RTTY. I added the digital interface window in N1MM+. The setup worked fine except when I TXed on slice A, headphone audio on slice B was muted. When I switched TX to slice B, headphone audio on slice B was unmuted, but slice A was muted. MMTTY continued to receive audio and decode RTTY signals on the slice where the headphone audio was muted. The absence of headphone audio on the muted slice is the problem I was trying to solve. The solution was sent to me by LZ2BE on the Flex Community and was part of the dialog on this topic though it has disappeared. Invoking the "back quote" key solves the problem. The back quote key on an American keyboard is just to the left of the number 1 key. Shifted it is the tilde key. Unshifted it is the back quote key, the one that fixes the problem.

Again thanks Len, Tim and Steve for your replies. I hope this post will remain on the community. This represents the best solution to the question I posed.

K4KGG, Larry

Lawrence Libsch

Len,

Thanks for your follow thru after I extended the question. Great support.

K4KGG, Larry

Steve...

There is a very good tutorial in the Flex librarian on setting up the 6000 series for SO2R. I just used it and it worked right away. K9CT was an author.

Kilo Three Scotch Whisky...

Steve...

There is a very good tutorial in the Flex librarian on setting up the 6000 series for SO2R. I just used it and it worked right away. K9CT was an author.

Kilo Three Scotch Whisky...