Receiver feedback during Tx (Not RF into the speakers)

WA6FXT Mike · September 2013

Last night, while on 20mtrs SSB, my 6700 got into a weird mode. When I keyed the Tx, I got a really bad feedback condition. Almost as if the receiver audio was still on. Didn't try other bands. Closing SSDR (v0.15.13.41) and re-opening cleared the problem. Single occurrence, so far.

WA6FXT Mike · September 2013

Update - I forgot to mention, I reduced power with no effect.

Ken - NM9P · September 2013

I had that glitch Friday on 40 ssb. It was delayed about 1/16 of a second and was disruptive to my conversation. It wasn't as loud as when MON is on, disappeared when the master mute was activated, and returned when unmuted. Restarting SSDR fixed it.

WA6FXT Mike · September 2013

Ken - Yeah! I forgot to mention the delay and that it also went away, while muted, if you muted the slice. Thanks, for reminding me.

K9DUR · September 2013

I have run into this a couple of times since installing v0.15.13. Both times it was in a situation where I couldn't stop & restart the client -- during the Indiana Traffic Net (75m LSB) & working a DX station (12m USB), I always run with a headset & the deleted echo is VERY disruptive. Have not found a way to make it happen on demand. 73, Ray, K9DUR

Jim Bryce W5HFS · September 2013

I made a report on this about an hour ago 0010 Z 15 Sept prior to seeing this chain. Same problem just bugged me during a QSO with a VE that is very interested in the 6000 series. Of course I didn't mention the problem as I'm sure Flex can run it down quickly, I hope. As I say in my earlier entry, I too cannot find a way to reproduce it on demand -- it just starts happening.

ai6re · September 2013

I had this problem while checking into the Flex Net today. It happens anytime I use receive B to transmit while Receiver A is running on the same band. Monitor is not on and the feedback is much louder and delaied and does not change with the volumn control. I believe this also affects my transmitted audio as net control said I was over modulating but hen OK on TX with RX-A. If I **** RX-B and use RX-A to TX then all is OK and working fine.

Ken - NM9P · September 2013

Now we are getting it narrowed down. It happened to me again on 80 meters last night. As I recall, I had had two pans open and had closed the top one with slice A and then was transmitting on the remaining one with B. I had also expanded my TX bandwidth to work some ESSB with some guys and noticed that the response didn't seem to be fully as wide as the filter settings I had set. (4K just for fun) Hope this info helps.

Ken - NM9P · September 2013

I have investigated it further. It happens WHENEVER I try to transmit on slice B on my 6500 if slice B is in a different pan. It also happens when slice B is in the same pan IF Slice A is on left side of the display and slice B is on the right and the frequency difference is far enough apare that the info flags have switched the other way. The example I have used is on 80 LSB. When A is to the left and B is to the right and the Flags are facing opposite directions, then TX on B is OK. If I move B further to the right to the point that the flag on B changes directions, then the "Echo feedback effect" is present. If I move back to the left so that the flag switches, then the TX on B is clear. I have repeated this several times. The effect seems to turn on when the slice information flag changes sides. The "Echo feedback effect" is a half-volume audio monitor signal coming out of the speakers (I assume phones, too) that does change volume according to the master volume. It is delayed about 1/16 to 1/8 second. If I activate the MON button, the volume is full monitor volume and not delayed. Definitely strange behavior. I verified this after a full power-down reset and computer reboot, too. I have never had it happen in Slice A. I don't know why I didn't put this together earlier. I have not tried it on other bands....but will do more testing.

Ken - NM9P · September 2013

ADDITIONAL UPDATE: On 80 LSB the behavior is like this... If the B Slice is less than 7.250 KHz ABOVE the A slice, the TX is clean. the next click of the knob to move the B Slice 7.30 Khz above the A slice and the effect begins. (It has nothing to do with the flag. The Zoom I had been using in the previous test just happened to coincide with this.) If I move B Slice back under the ABOVE frequency limit, then TX is clean again. ALSO... If B Slice is less than 4.350 KHz BELOW the A Slice, then TX on B is clean. If I move B Slice one more click below the A slice, then TX has the effect. Move it back up within the window of 4.350 below to 7.250 above and the B Slice TX is clean. outside those parameters and it is clean. I reproduced this with A Slice on 3.800 Mhz and on 3.900 Mhz. It was the same frequency difference on 160 Meters, BUT on 20 and 10 meters on Upper Sideband, the frequency limits were different, but once I found a limit, it was constant for that test. So far... ANYTIME I try to transmit on slice B in a different pan window from Slice A it has been affected.

Jim Bryce W5HFS · September 2013

Ken, NM9P, Thank you for persistent and exacting tests. I'm sure your efforts will be of great help to Flex in solving this serious problem. It was such a surprise for it to appear after essentially flawless performance in "routine" operations over the last couple of months. Sometimes striving for final perfection creates unexpected setbacks. You've laid the foundation to eliminate this one. --Jim, W5HFS

Brad - N6SPM · September 2013

Just wanted to chime in with another instance of the delayed echo on SSB while operating split. I have not put in the time to consistently replicate it, but it looks like Ken has it defined pretty well. I only had one slice open, with the Tx up and on the right side of the receive. The delay is just enough to be really mentally disruptive! I was able to replicate it on the same Dx station, same band on a couple of occasions. Brad - N6SPM

Tom · September 2013

Ditto on 40M, "A" slice. Went away when I killed SSDR and restarted.

Jim Bryce W5HFS · September 2013

This reply was created from a merged topic originally titled Feedback on Sideband. Feedback on sideband: Running 0.15.13 on 6700. I've only been receiving on both sideband and digital since new version came out until today. I responded to a CQ on 17 and immediately heard audio feedback. I switched to dummy load, same. I disconnected ACC cable to SignaLink USB, same. I disconnected speakers and phones, same. I changed from Heil 781 to original handheld Flex supplied mike in front jack, same. I changed computers, same. At that time I had one receiver on 20 and was transmitting on 17. I changed to transmit on 20 and have open receiver on 17, gone. I reversed, transmit again on 17 and receive on 20, gone. No problem now. I'm preparing article for the "Journal of Irreproducible Results."

Greg - K5GJ · September 2013

First, I want to thank everyone for the extremely detailed feedback (pun intended!). It will be very helpful during our upcoming testing. While we hadn't seen this in the lab or field testing, we believe it's a real issue. We also believe that changes we have made in related software will resolve this issue with the next release. We will be sure and test the scenarios above to make sure it's taken care of. Be sure and let us know if you see it with the next release. Thanks again all! 73, Greg - K5GJ

Joe WD5Y · September 2013

I have had this on 80 meters; I started looking into an RFI issue. It is very low and the amplitude does not increase with more power out (amplifier in line) which is why I was confused whether it was RFI or not. I will check again after a restart. Glad this came up as hopefully I will not chase the wrong problem. 73's Joe WD5Y

Tim - W4TME · September 2013

This defect has been fixed in SmartSDR v0.16.x and greater

Receiver feedback during Tx (Not RF into the speakers)

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