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Version 5 board 10 meter SSB Spur Test #ubitx

 

Got a single/two tone audio generator in from Pacific Antenna yesterday.? Took about 1.5 hours to build it and check it out.? Made up a cable to go to the microphone input on the uBITX and set the spectrum analyzer up as close to what I was told when I asked Allison for the parameters.

the 16 MHz spur is there and still out of spec by a little.

I had a little less than 50 millivolts Peak to Peak audio at 1 KHz input to the mic jack, 2.6 watts output power (adjusted audio to jus below where output stopped increasing and backed it off until it dropped about 1 dB.

First picture is baseline trace with no signal being transmitted and the 2nd is the actual measurement.
Test frequency was 28.400 MHz.? 2 spurs, 1 at 16.64, 1 at 17.34 and a third spike not too far below the 28.4 carrier frequency that I ignored for this test as I don't know what it is caused by.

I'm primarily a CW operator so when it comes to SSB measurements, I'm a complete novice.? I did do the same check using CW on the same frequency and there were no spurs I could find.

If anyone wants further SSB testing, they will have to do it themselves as I need the spectrum analyzer for a completely other project and a totally different test setup.

Jim Sheldon, W0EB
TSW Project Coordinator
 

Thanks Jim, I really appreciate your independent tests. Previous versions, at least ver. 3 had a serious SSB spur issue especially on the 21mhz band, may you perform if possible a test, let's say at 21.3mhz SSB?


Il 02/mar/2019 12:43, "Jim Sheldon" <w0eb@...> ha scritto:
Got a single/two tone audio generator in from Pacific Antenna yesterday.? Took about 1.5 hours to build it and check it out.? Made up a cable to go to the microphone input on the uBITX and set the spectrum analyzer up as close to what I was told when I asked Allison for the parameters.

the 16 MHz spur is there and still out of spec by a little.

I had a little less than 50 millivolts Peak to Peak audio at 1 KHz input to the mic jack, 2.6 watts output power (adjusted audio to jus below where output stopped increasing and backed it off until it dropped about 1 dB.

First picture is baseline trace with no signal being transmitted and the 2nd is the actual measurement.
Test frequency was 28.400 MHz.? 2 spurs, 1 at 16.64, 1 at 17.34 and a third spike not too far below the 28.4 carrier frequency that I ignored for this test as I don't know what it is caused by.

I'm primarily a CW operator so when it comes to SSB measurements, I'm a complete novice.? I did do the same check using CW on the same frequency and there were no spurs I could find.

If anyone wants further SSB testing, they will have to do it themselves as I need the spectrum analyzer for a completely other project and a totally different test setup.

Jim Sheldon, W0EB
TSW Project Coordinator
 

Sorry Iz, I simply won't have time to run any more tests for now - maybe in several weeks when I finish the big project I'm working on now.? There are others out there that have the capability to do these tests too, maybe one of them could do it and post the results.? We need more independent, non biased tests from others anyway.

Jim
 

I fully understand, thanks for sharing your analysis so far.


Il 02/mar/2019 13:29, "Jim Sheldon" <w0eb@...> ha scritto:
Sorry Iz, I simply won't have time to run any more tests for now - maybe in several weeks when I finish the big project I'm working on now.? There are others out there that have the capability to do these tests too, maybe one of them could do it and post the results.? We need more independent, non biased tests from others anyway.

Jim

 

Jim,

Thank-you for running the tests and sharing your information.?

73
Evan
AC9TU
 

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Just got my v5 board on Saturday. Got it up and running today. I notice on all bands when keying up using just PTT in SSB a carrier is present and It’s noticeable on 75 meters when making QSO’s as reported(I don’t see it on a watt meter) going higher in frequency it’s gets worse. On 28mhz it’s almost 1/2 watt of carrier (no mic) just PTT. Any way to suppress the carrier? Any one else have this issue with the new v5 board??

Thank you Bill NG1P

This is my third ubitx build..


On Mar 2, 2019, at 9:10 AM, Evan Hand <elhandjr@...> wrote:

Jim,

Thank-you for running the tests and sharing your information.?

73
Evan
AC9TU

 

This suggests that you BFO is putting the audio too close to the SSB filter.? I ran a number of tests when checking out my SDRPlay as a signal analyzer and found the same thing.? I had to adjust the BFO lower in frequency to remove the carrier.? That of course raised the audio "tone" of the received signal.? It became a balance between sound quality and carrier reduction.

Not sure how to do this without a SA.? Maybe try a 500hz adjustment and check PTT output without any sound.? Repeat by changing by another +/-100 hz? until it is just barely measurable and back up the 100 hz.? I did that method using the SA to measure output.? Ultimately my BFO setting was 11.995500 for the v4 vs the stock 11.997000.? I was able to get the carrier below -30db from the two tone signal.

Above are my experiences, yours maybe different.

73
Evan
AC9TU
 

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Thanks I’ll give that a try and see how that goes.


On Mar 3, 2019, at 1:59 PM, Evan Hand <elhandjr@...> wrote:

This suggests that you BFO is putting the audio too close to the SSB filter.? I ran a number of tests when checking out my SDRPlay as a signal analyzer and found the same thing.? I had to adjust the BFO lower in frequency to remove the carrier.? That of course raised the audio "tone" of the received signal.? It became a balance between sound quality and carrier reduction.

Not sure how to do this without a SA.? Maybe try a 500hz adjustment and check PTT output without any sound.? Repeat by changing by another +/-100 hz? until it is just barely measurable and back up the 100 hz.? I did that method using the SA to measure output.? Ultimately my BFO setting was 11.995500 for the v4 vs the stock 11.997000.? I was able to get the carrier below -30db from the two tone signal.

Above are my experiences, yours maybe different.

73
Evan
AC9TU

Gordon Gibby
 

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Look at the receiver output of the background galactic white noise using the waterfall of ANY digital protocol. ?

It should fall off under 500 Hz. ??


On Mar 3, 2019, at 22:01, bill richardson <ng1p.bill@...> wrote:

Thanks I’ll give that a try and see how that goes.


On Mar 3, 2019, at 1:59 PM, Evan Hand <elhandjr@...> wrote:

This suggests that you BFO is putting the audio too close to the SSB filter.? I ran a number of tests when checking out my SDRPlay as a signal analyzer and found the same thing.? I had to adjust the BFO lower in frequency to remove the carrier.? That of course raised the audio "tone" of the received signal.? It became a balance between sound quality and carrier reduction.

Not sure how to do this without a SA.? Maybe try a 500hz adjustment and check PTT output without any sound.? Repeat by changing by another +/-100 hz? until it is just barely measurable and back up the 100 hz.? I did that method using the SA to measure output.? Ultimately my BFO setting was 11.995500 for the v4 vs the stock 11.997000.? I was able to get the carrier below -30db from the two tone signal.

Above are my experiences, yours maybe different.

73
Evan
AC9TU

 

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Adjusting the BFO did the trick. For my v5 the BFO is set at 11.055.3

Both v3 the BFO is at 11.996.1
One v4 is at 11.996.7

Thanks!


On Mar 3, 2019, at 6:47 PM, Gordon Gibby <ggibby@...> wrote:

Look at the receiver output of the background galactic white noise using the waterfall of ANY digital protocol. ?

It should fall off under 500 Hz. ??


On Mar 3, 2019, at 22:01, bill richardson <ng1p.bill@...> wrote:

Thanks I’ll give that a try and see how that goes.


On Mar 3, 2019, at 1:59 PM, Evan Hand <elhandjr@...> wrote:

This suggests that you BFO is putting the audio too close to the SSB filter.? I ran a number of tests when checking out my SDRPlay as a signal analyzer and found the same thing.? I had to adjust the BFO lower in frequency to remove the carrier.? That of course raised the audio "tone" of the received signal.? It became a balance between sound quality and carrier reduction.

Not sure how to do this without a SA.? Maybe try a 500hz adjustment and check PTT output without any sound.? Repeat by changing by another +/-100 hz? until it is just barely measurable and back up the 100 hz.? I did that method using the SA to measure output.? Ultimately my BFO setting was 11.995500 for the v4 vs the stock 11.997000.? I was able to get the carrier below -30db from the two tone signal.

Above are my experiences, yours maybe different.

73
Evan
AC9TU

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