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SSB Xmit repair

 

I was doing POTA yesterday with the V.5 shown in my avatar, when a caller asked me if I was [intentionally] running double sideband.? He was really cool about it and volunteered to send a short video capture of my signal. I've included a still from that.
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I haven't adjusted anything for at least 2 years and it's spot on frequency,? so I'm loathe to change anything too quickly.? I also have forgotten or am unaware that any if the VFO or tuning parameters alter the transmit side of things.? Again, it's been a while and I shall be re-reading the tuning methodology today.
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That said, i apparently misinterpreted or missed something before, unless it's a part failure. Would anyone whose good on the earlier models be able to suggest a good methodology for placing all of my RF energy into just one 3kc channel?? I'm doing about 20 watts on 40m, so getting the full benefit - and not occupying more space than I need - would be an improvement.
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Tnx,
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K3RTA
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?

IMG_3218.mov
IMG_3218.mov

 

Hi Ted,
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The short answer is that both the calibration (master and BFO) settings can cause the filter to be misaligned with the signal.? Also, it can be a failure in the modulator in that one-half of the BAT54FL diode could have failed or other problems with the modulator.? If the issue is recent, it is most likely a failure rather than a bad calibration.
?
I saw on your QRZ page that the v5 is running the KD8CEC software with a Nextion screen.? That makes it easy to do some checks and possible adjustments after saving the current configuration.? Can you pull up the software settings page and note the BO value?? It should be close to 11.056 kilohertz.? If not, I suggest using the Memory Manager software to save the current values and perform a complete recalibration.??
?
I have always struggled using WWV as the calibration source as the sidetones get in the way of determining beat frequency.? I have a 10MHz standard that I use through an attenuator for the calibration source.? I also use a signal generator calibrated using the standard to verify accuracy.? The higher the calibration frequency, the better the accuracy.? If in a pinch, you can tune down to the commercial AM band and use a known station as the standard.? I have found this easy to do (other than all the turns of the tuning dial to get down to the station) but less accurate.
?
If the calibration values seem correct, then the only test I know for the modulator is to pull the diode and replace it with a known-good one.? That does require SMD rework skills.? I suggest not using discrete diodes for this replacement, as they may not have the matched characteristics.
?
Before you start tearing apart your radio, I have a question: The video clip shows USB as the communication mode.? Were you running a USB on 40 meters?
?
73
Evan
AC9TU
 

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Just to add to Evans first para. If a diode has failed or mostly bad solder then the RX would have dropped sensitivity.

Good Luck with a fix!

Raj, vu2zap

On 07/03/2025 6:59 PM, Evan Hand via groups.io wrote:

Hi Ted,
?
The short answer is that both the calibration (master and BFO) settings can cause the filter to be misaligned with the signal.? Also, it can be a failure in the modulator in that one-half of the BAT54FL diode could have failed or other problems with the modulator.? If the issue is recent, it is most likely a failure rather than a bad calibration.
?
I saw on your QRZ page that the v5 is running the KD8CEC software with a Nextion screen.? That makes it easy to do some checks and possible adjustments after saving the current configuration.? Can you pull up the software settings page and note the BO value?? It should be close to 11.056 kilohertz.? If not, I suggest using the Memory Manager software to save the current values and perform a complete recalibration.??
?
I have always struggled using WWV as the calibration source as the sidetones get in the way of determining beat frequency.? I have a 10MHz standard that I use through an attenuator for the calibration source.? I also use a signal generator calibrated using the standard to verify accuracy.? The higher the calibration frequency, the better the accuracy.? If in a pinch, you can tune down to the commercial AM band and use a known station as the standard.? I have found this easy to do (other than all the turns of the tuning dial to get down to the station) but less accurate.
?
If the calibration values seem correct, then the only test I know for the modulator is to pull the diode and replace it with a known-good one.? That does require SMD rework skills.? I suggest not using discrete diodes for this replacement, as they may not have the matched characteristics.
?
Before you start tearing apart your radio, I have a question: The video clip shows USB as the communication mode.? Were you running a USB on 40 meters?
?
73
Evan
AC9TU
 

?
Hi, Evan, and all.
?
I appreciate the leads.? Here are some answers to your queries -
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On Fri, Mar 7, 2025 at 08:29 AM, Evan Hand wrote:
Can you pull up the software settings page and note the BO value?? It should be close to 11.056 kilohertz.?
?
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See attached;? SSB is set tp 11.056875. That would have been a really good call, though I'm not against trying all over again.??
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If you think this may help, I happen to have a small "TinySA" that I've played with, but the best I can do while learning what it can do is to compare an IC-706MK2g signal on the same frequency, and see how they differ.?
?
?
If the calibration values seem correct, then the only test I know for the modulator is to pull the diode and replace it with a known-good one.? That does require SMD rework skills.? I suggest not using discrete diodes for this replacement, as they may not have the matched characteristics.
I happen to have a previously-abused mainboard handy. Swapping out the dual diode would not be that much trouble here.

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Before you start tearing apart your radio, I have a question: The video clip shows USB as the communication mode.? Were you running a USB on 40 meters?
?
I'd been working a number of other folks before and after this follower came along, so either the video fails to show his entire screen and something's missing, or, maybe he swapped sidebands on his end before gathering evidence.? And now at home - using the redundant radio - I can indeed hear equally well on both side bands from 2 feet away at least.
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So,? unless the collective believes the BFO or other calibration is off, I'm willing to swap the diode pair and will stand by.....
?
?
72,
?
Ted
K3RTA
?
?
?
?
 

Hi Ted,
?
Since you have the Memory Manager software, I suggest you save the values to a file and do the BFO adjustment again.??
?
I thought about the symptoms again and do not believe the modulator failure is the most likely cause.? The carrier is significantly reduced in the video.? If the modulator failed, I would expect a much higher value for the carrier (BF0).? Also, the SSB crystal filter would limit the output to a 3KHz span.? It could be that the SSB filter is damaged somehow.
?
Hopefully, others can chime in here, as I cannot explain the data.
?
73
Evan
AC9TU
 

开云体育

He could offset the carrier a bit one way or the other, (maybe by 1500 Hz ?) and then plot the response of the filter by looking at the noise pattern on any waterfall display

It would be a great learning exercise also!!

Gordon kx4z?




On Mar 9, 2025, at 10:37, Evan Hand via groups.io <elhandjr@...> wrote:

?
Hi Ted,
?
Since you have the Memory Manager software, I suggest you save the values to a file and do the BFO adjustment again.??
?
I thought about the symptoms again and do not believe the modulator failure is the most likely cause.? The carrier is significantly reduced in the video.? If the modulator failed, I would expect a much higher value for the carrier (BF0).? Also, the SSB crystal filter would limit the output to a 3KHz span.? It could be that the SSB filter is damaged somehow.
?
Hopefully, others can chime in here, as I cannot explain the data.
?
73
Evan
AC9TU
 

Solution found.

It was chiefly the BFO - and for all I know, I might have set it wrong in the first place 2-3 years ago when I swapped out the board, and never knew.??

I took the advice on the KD8CEC site to use an audio spectrum analyzer program [for Android, i use "Spectroid"] to listen to the rig on a clear frequency. I? tuned the white noise for as even a blanket between 300hz and 3khz as I can judge.? I then hooked up Memory Manager and re-tuned to WWV by making changes to the master clock value rather than dealing with all of that other carrier cal trouble.??

At this point, I hollered into a dummy load and discovered I could hear only the desired sideband on a redundant radio, upper or lower, corresponding with the intended one.?

CW followed, moving the CW BFO around until I got the tightest curve I could manage between letting in as much 600hz as it can while rejecting as much treble as it can. There's a CW filter add-on here, but its nice to be able to trim it a little beforehand.?

I sure appreciate the encouragement.? Sometimes we just have to go back to the beginning and see if following the instructions on a new day (or new year) improves the outcome.


Tnx & 72

Ted
K3RTA?


On Sun, Mar 9, 2025 at 11:40, Gordon Gibby KX4Z via groups.io
<docvacuumtubes@...> wrote:
He could offset the carrier a bit one way or the other, (maybe by 1500 Hz ?) and then plot the response of the filter by looking at the noise pattern on any waterfall display

It would be a great learning exercise also!!

Gordon kx4z?




On Mar 9, 2025, at 10:37, Evan Hand via groups.io <elhandjr@...> wrote:

?
Hi Ted,
?
Since you have the Memory Manager software, I suggest you save the values to a file and do the BFO adjustment again.??
?
I thought about the symptoms again and do not believe the modulator failure is the most likely cause.? The carrier is significantly reduced in the video.? If the modulator failed, I would expect a much higher value for the carrier (BF0).? Also, the SSB crystal filter would limit the output to a 3KHz span.? It could be that the SSB filter is damaged somehow.
?
Hopefully, others can chime in here, as I cannot explain the data.
?
73
Evan
AC9TU
 

开云体育

Great !!



On Mar 9, 2025, at 21:55, Ted via groups.io <k3rta@...> wrote:

?Solution found.

It was chiefly the BFO - and for all I know, I might have set it wrong in the first place 2-3 years ago when I swapped out the board, and never knew.??

I took the advice on the KD8CEC site to use an audio spectrum analyzer program [for Android, i use "Spectroid"] to listen to the rig on a clear frequency. I? tuned the white noise for as even a blanket between 300hz and 3khz as I can judge.? I then hooked up Memory Manager and re-tuned to WWV by making changes to the master clock value rather than dealing with all of that other carrier cal trouble.??

At this point, I hollered into a dummy load and discovered I could hear only the desired sideband on a redundant radio, upper or lower, corresponding with the intended one.?

CW followed, moving the CW BFO around until I got the tightest curve I could manage between letting in as much 600hz as it can while rejecting as much treble as it can. There's a CW filter add-on here, but its nice to be able to trim it a little beforehand.?

I sure appreciate the encouragement.? Sometimes we just have to go back to the beginning and see if following the instructions on a new day (or new year) improves the outcome.


Tnx & 72

Ted
K3RTA?


On Sun, Mar 9, 2025 at 11:40, Gordon Gibby KX4Z via groups.io
<docvacuumtubes@...> wrote:
He could offset the carrier a bit one way or the other, (maybe by 1500 Hz ?) and then plot the response of the filter by looking at the noise pattern on any waterfall display

It would be a great learning exercise also!!

Gordon kx4z?




On Mar 9, 2025, at 10:37, Evan Hand via groups.io <elhandjr@...> wrote:

?
Hi Ted,
?
Since you have the Memory Manager software, I suggest you save the values to a file and do the BFO adjustment again.??
?
I thought about the symptoms again and do not believe the modulator failure is the most likely cause.? The carrier is significantly reduced in the video.? If the modulator failed, I would expect a much higher value for the carrier (BF0).? Also, the SSB crystal filter would limit the output to a 3KHz span.? It could be that the SSB filter is damaged somehow.
?
Hopefully, others can chime in here, as I cannot explain the data.
?
73
Evan
AC9TU

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