6600 or 6700 SO2V-like operations with N1MM+

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  • Updated 5 months ago
I have a few questions for the "SO2R" N1MM+ operators that use radios with 2 SCUs. My questions stem from an issue I have with my 6600M. I would like to have it behave like SO2V on the same band (some "spot-jumping" AMQ short cuts in SO2R mode just to the first matching band, which is an issue for me), SO2R on different bands and be protected in case of same band operations and different antennas (by mistake). 

1. Assuming you use the N1MM+ SO2R option when on different bands, do you switch to SO2V when using the same band when running in one slice and S&P on the same band? Or do you stay in SO2R mode?

2. If you stay in SO2R mode, how do you protect front end in case of having slice A and B on teh same band and different antennas? I use FRStack, but wanted to know how others do it. 

3. When you are on the same band, how do you use the AMQ effectively without being QSYed from your CQ frequency? Maybe I am doing something wrong...

4. If there is a workflow issue for SO2R ops, I am open for N1MM+ improvement ideas...Send them my way or in this community and I will discuss with the team.  

73
Andy
KU7T
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Andy - KU7T

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Posted 5 months ago

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Al Dewey

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Andy;

Here is what I do based on a hint from K0PC. I am using a Flex 6600M and N1MM+

For contests like the current 10M contest where I wished to have Slice A on CW and Slice B on SSB, I simply stayed in SO2R mode.  I used the same physical Antenna (a 3 element Yagi) and connected it to the ANT 1 Jack.  Ant 2 not used.  I configured both slices to use ANT1 as both the Transmit and Receive Antenna.

N1MM+ would not allow me to put both slices on the same band.  However, if I over road that by changing the band using the radio, that worked.  The N1MM error message eventually went away. 

Granted , this did not allow me to listen on SSB while transmitting on CW but I was OK with that as that would be the situation with SO2V anyway - right?

Anyway, this solution worked for me.  I could not get things to work right when I set N1MM+ to SO2V.

73,

AL, K0AD
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Michael Walker, Employee

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Hi Andy

Let me try to answer this.

First, the all the Flex radios have amazing front end over load protection.  If you start to exceed their limits you will receive a warning message.  The RF level is pretty high (I think it is quoted in the hardware manual -- I'll need to go check, but the db value is quoted).

Also, keep in mind that when in TX, the RX antenna is still connected to the front end of the radio regardless of the band you are on with another slice.   This seems to be a misconception (with all HF radios) that as long as you aren't on the same band, then you don't need to worry about it.  You need to check with the manufacturer of each radio.  

Yes, N1MM restricts you from going on the same band on both VFO's in SO2R mode.  This has been discussed with them to allow this, but at this time, they have chosen not to allow it.   However, you can actually do it by not using N1MM to change frequencies but by using the radio.  Give it a try in SO2R mode.  There is a N1MM message that says you must use the radio to put both slices on the same band.

Short story is that I don't think it will work the way you expect in SO2V.  You have to be in SO2R.  OTRSP works as well.

Mike 
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Andy - KU7T

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Hi Michael,

The front end protection of the radio is still a mystery to me. 

I was under the impression that there is a lot more front end protection when the radio is not in WIDE mode. Meaning there is a band pass or some sort of enabled. So, in the normal case of being on different bands and not in WIDE mode, the protection would be there automatically kind of like having an external band pass filter in line. Is that not true?

When on the same band, obviously the WIDE or not WIDE does not matter, as the filters are "wide open". This is the worst case. I did not plan in really doing this without really calculating if it is OK. However, calculating this is hard, and really just a ball pack number. Are you saying that the radio should tell before it fails, so it "may be" OK to try it without calculating? One scenario that comes  my mind is this: Two towers, not beaming at each other are OK, but beaming at each other is not.  


Andy
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Michael Walker, Employee

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Hi Andy

The radio has a lot of Front End protection.   

I want to go talk to engineering about this, but first, I pulled this out of the SmartSDR manual.  I've sure you seen it.

At some time, I will try to get Steve or Gerald to comment on this for you, but it may take a bit.  Personally, I have turn 2 slices on 80 in the middle of a contest without issue.

I doubt this will answer all your questions, but I do know it is pretty tough.

Mike




39.5 FULL DUPLEX ANTENNA ISOLATION REQUIREMENTS

For successful FDX operation, it is essential to understand and plan for sufficient transmit to receive antenna isolation to prevent receiver overload and/or damage. The FLEX-6000 FDX Power Calculation Worksheet can aid in the calculation of antenna isolation and power levels that are suitable for a specific station.

The FLEX-6000 Signature Series transceivers are designed to disconnect the receiver from the antenna when signal levels are +18 dBm to +22 dBm depending on frequency. The front-end protection circuits will begin to engage at approximately +15 dBm. Front-end overload of the SCU will occur with a single tone in the range of +8 dBm with the preamp off. Increasing the preamp gain will lower the overload point by the amount of the added gain.

To provide suitable headroom to prevent SCU overload, we recommend that transmit to received signal strength be limited to a worst case of -20 dBm or lower at the antenna input. With 20 dB of preamp gain, this would provide a single tone input of 0 dBm to the A/D converter leaving about 8 dB of headroom. More isolation is better.

One of the best resources for information on achieving antenna isolation is:

"Managing Interstation Interference, Revised Second Edition" by George Cutsogeorge, W2VJN.