MOX locks in TX mode on CW after sending a few characters

K7JV

FLEX 6400 to a dipole, unmatched SWR < 1.5:1.  Connected to the WAN/LAN via Ethernet.
Maestro connected via wifi to the FLEX 6400.  Both running the most current software/firmware.
The combination is only slightly over a month old, and both were new, not reconditioned.

Problem:  When I send CW (Bencher paddles, Maestro internal keyer) at between 15 and 20 WPM, after three or four characters the MOX light no longer winks red, but latches red and the radio stays in the TX mode.

When this happens, I have to press the MOX key twice before the radio will go back to RX.

Anything even close to QSK is not possible.

It is the short elements (dits) that cause it to latch.

I have noted that if I tap a single dit, the MOX light actually flickers twice.  Longer elements (dah's) do not cause the MOX light to flicker.  If it flickers, it is going to latch the MOX.  If it does not flicker, but just comes red like it is supposed to, the MOX works like it should and does not latch.

I have tried it with Breakin ENABLED and DISABLED.  With it DISABLED, the latching problem goes away, but the CW transmitted by the radio is unreadable, broken bits of signal, according on on-air reports.  With it ENABLED, the on-air reports are good, but the MOX stays latched.

I did learn that "Breakin" does NOT refer to QSK.  Its function really is that of a CW VOX in that I was told that with it disabled, the radio should not transmit.

I have tried it with varying durations of DELAY with no joy.

I tried downgrading to the next lower lower software version on the radio, but that didn't make any difference.

I have tried numerious re-boots of the Maestro, the FLEX 6400, and both the Maestro and the FLEX with no joy.

I am at my wits end.  I had the problem about a week and a half ago, and it seemed to "heal" on its own.  Then yesterday it came back.  Today it has not healed on its own.

Thoughts?

K7JV - Jim (Idaho)

Mike-VA3MW

Duane_AC5AA

K7JV

Hi, Michael.  I just connected the Maestro directly to the radio and the problem did not go away.  FYI, yesterday I checked the antenna impedance and SWR at the coax fitting at the radio with an MFJ antenna analyzer, and the values were SWR 1.3:1, resistance 63 ohms real and 8 ohms reactive, so that is a pretty good match.  I would not expect alot in the way of feedline radiation RFI issues.  The antenna is a B&W folded dipole in the attic, fed by RG-8 coax and their 2 kW balun unit at the terminals of the antenna.  The cable from the Bencher to the Maestro is coiled, and only about 14" long.  On 3.572 MHz, that would not likely be much of a portal for RFI, either, I don't think.  Also, I just tried it on 40M and 20M, and the problem does not appear to be frequency related.

Thank you for your thoughts, and I'm interested in where to try to go from here.  Ken has been working with me in the past on this, and we thought we were good.  However the problem came back.

Also, are you the Michael that we met at the Yuma hamfest, in mid February, this year?  That was a great show!

K7JV

Thank you, Duane.  I don't currently have any ferrite chokes, but take a peek at what I just sent to Michael.  I have some chokes in our RV, as well as another Bencher paddle that has a more "user-friendly" phono cable on it that I want to swap with the one here, in the shack.  I will bring some home with me and if we haven't worked it out by then, I'll stick them on the line.

KD0RC

Neil D Friedman N3DF

Michael says he doesn't think you have an RFI problem, and that's good enough for me.  However, you might note that 100 watts into an attic antenna can result in RFI issues, even though the SWR match is perfect.  

K7JV

K7JV

I will agree, Neil.  I forgot to mention that the problem doesn't go away, even when I turn the TX power level clear to zero.  That does totally take RFI from the feedline or antenna out of the equation.  It is true that even with the CW output power at zero, the problem still exists.

Mike-VA3MW

One more test. Turn your RF power to zero and test. That will eliminate RF as a possible contributor. If Yuma that wasn’t me M

K7JV

Mike-VA3MW

K7JV

KD0RC

Excellent!  Glad to hear you are making progress.  Good to hear you have a way to stay on CW until this is resolved. 

Len

Mike-VA3MW

Hi

I'm the only Mike, and I wasn't there.     I wonder who it was.  It might have been Matt, but I am not sure he went.  Maybe it was Dave.

I'll convert this to a Support ticket for you.

73

KD0RC

Mike, I just love this kind of support. The fact that you and other Flex employees stay engaged on this forum is a real testament to Flex customer commitment. 73, Len, KD0RC

K7JV

Thank you Mike. We may have two, but hopefully they’ll see that and delete one. I did a pretty thorough submission last night. Note I’ll keep my fingers crossed. And “times two” on what Len said.

K7JV