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ubitx spurs?

 

I set up to do some SSB testing getting putting about 50Vpp in.
I don't know if I read the right peaks or not, but I looked for
the strongest signal that wasn't a harmonic.

Don't know how I skipped 17m, but that's life.  I'll do it next time.

I've replaced the relays and L5/L7.

Does this look about right or am I looking at the wrong thing?

It looks like no 12m or 10m based on spars or 80m due to harmonics for me at this point.

John
W1JDS


Curt
 

John

info appreciated.  I don't think you are likely using 50 volts audio -- maybe 50 mV ?  There may be more variation in the audio gain than RF perhaps.  I suggest you watch the output power as you adjust the audio, as producing an expected RF output tells us you are measuring spurs while simultaneously getting several watts of RF output. 

You didn't happen to say if this is v5 or a previous version?

I recognize that 12m spur being 5 MHz away -- mine has similar spurs almost equally below and above the carrier (one is a mixer spur, the other seems to be a signal passing through the mixer a second time (RF from PA leaking back into mixer input).  What you label as separation looks like you have subtracted the spur level from the main carrier?  By convention these are given as a negative value.  If you are outputting say 3 or more watts at 10m -- I really like your numbers -- they are 8 dB better than my v4.  Note your worst spurs are up there also, but yours are close to compliance - indeed if your rig is simultaneously outputting desired transmit power. 


The SSB spurs you are measuring tend to be a worse problem at the highest frequencies - I have non-compliant spurs on SSB only at 15, 12 and 10 meters. 

Also you need to seprately measure the worst harmonic.  Note these mostly impact bands at 20m and below, since the PA doesn't transmit as efficiently up above 10m where these spurs would land if they start at 18 MHz or higher. 

Be patient and you should get some good measurements. 

Curt

iz oos
 

Indeed, they seem almost good results, especially on the 15m band, which was the most critical for spurs. Which version of ubitx do you have? If you use an ordinary (high - pass) tuner, you should be fine on 10m and possibly on 12m too. Thumbs up!


Il 08/apr/2019 10:33, "John Sutter" <jds@...> ha scritto:
I set up to do some SSB testing getting putting about 50Vpp in.
I don't know if I read the right peaks or not, but I looked for
the strongest signal that wasn't a harmonic.

Don't know how I skipped 17m, but that's life.  I'll do it next time.

I've replaced the relays and L5/L7.

Does this look about right or am I looking at the wrong thing?

It looks like no 12m or 10m based on spars or 80m due to harmonics for me at this point.

John
W1JDS


Curt
 

Iz

with these numbers I would speak softer into the microphone and be just fine.  important to see if they correspond to 'full' output power, if so I think most of us would be thrilled with them.  (but do check the harmonics also!)

a typical v4 uBITX has SSB spurs on 15, 12 and 10 meters that are too high for a tuner to confidently address. 

I am very curious about this data as I am not getting useful results with a added 45 MHz xtal filter stage.  If I figure out who is selling those shielded inductors in NA, I would be interested in them given this data. 

Curt

 

I guess it could have been worse, I could have types 50MV :-)

This is a v3 that I finally got around to playing with a couple of months ago.
It had been in the project stack for quite a while.  For now it's just built into
the shipping container until I decide what it's going to be when it grows up.
I have a JackAl board about ready if it goes that way.

I've attached spectrum captures for 20m and 40m.  Didn't take them of other
bands.  The chart below does show the general trend higher frequency -> worse
spurs.  I tried to cherry pick numbers for 12m but still couldn't quite get there :-)



Thanks for the feedback.  As always, more learning to do.

John
W1JDS

Curt
 

John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt

iz oos
 

John, you made an excellent job with the relay replacement and the two inductors mod, for the higher bands you might also consider to add the LPF Farhan filter before the 45mhz filter. I have done it with two small (green-white) toroids (12turns to get exactly the required inductance) and a cap. It is rather easy to install (Manhattan style).


Il 08/apr/2019 22:00, "Curt via Groups.Io" <wb8yyy=yahoo.com@groups.io> ha scritto:
John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt

Ashhar Farhan
 

you should setup the RV1 properly. Set it to half-way mark.
- f

On Tue, Apr 9, 2019 at 8:50 AM iz oos <and2oosiz2@...> wrote:

John, you made an excellent job with the relay replacement and the two inductors mod, for the higher bands you might also consider to add the LPF Farhan filter before the 45mhz filter. I have done it with two small (green-white) toroids (12turns to get exactly the required inductance) and a cap. It is rather easy to install (Manhattan style).


Il 08/apr/2019 22:00, "Curt via Groups.Io" <wb8yyy=yahoo.com@groups.io> ha scritto:
John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt

iz oos
 

I meant before the 45mhz mixer. Being the LPF exactly the same and in the same position found in ver5 of the ubitx


Il 09/apr/2019 05:20, "iz oos via Groups.Io" <and2oosiz2=gmail.com@groups.io> ha scritto:

John, you made an excellent job with the relay replacement and the two inductors mod, for the higher bands you might also consider to add the LPF Farhan filter before the 45mhz filter. I have done it with two small (green-white) toroids (12turns to get exactly the required inductance) and a cap. It is rather easy to install (Manhattan style).


Il 08/apr/2019 22:00, "Curt via Groups.Io" <wb8yyy=yahoo.com@groups.io> ha scritto:
John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt

 

I did post some CW data a few weeks back as I swapped out the relays and inductors.
Some of the data is suspect given unexpectedly high power readings.  If you can read an
Excel file I can send the whole thing to you directly.  In general all was good after
the mods except for 80m where the first harmonic after the fundamental as off by 6 dB.
I've only checked 10,20,30,40,80m in CW.

I am using an Agilent 33220A function generator.  I'll see if I can drive it up to similar
power levels Friday night aka "My Time".  I'll try to cover all bands next time.




On 4/8/2019 12:59 PM, Curt via Groups.Io wrote:
John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt

 

Thanks, I'll look into that.

John
W1JDS

On 4/8/2019 8:20 PM, iz oos wrote:

John, you made an excellent job with the relay replacement and the two inductors mod, for the higher bands you might also consider to add the LPF Farhan filter before the 45mhz filter. I have done it with two small (green-white) toroids (12turns to get exactly the required inductance) and a cap. It is rather easy to install (Manhattan style).



 

I'm afraid it was already set to the half way mark.
Is there something particular I should be looking for?

At this point I'm having enough fun taking measurements and
improving things as I go along.

Thanks,

John
W1JDS


On 4/8/2019 8:46 PM, Ashhar Farhan wrote:
you should setup the RV1 properly. Set it to half-way mark.
- f

On Tue, Apr 9, 2019 at 8:50 AM iz oos <and2oosiz2@...> wrote:

John, you made an excellent job with the relay replacement and the two inductors mod, for the higher bands you might also consider to add the LPF Farhan filter before the 45mhz filter. I have done it with two small (green-white) toroids (12turns to get exactly the required inductance) and a cap. It is rather easy to install (Manhattan style).


Il 08/apr/2019 22:00, "Curt via Groups.Io" <wb8yyy=yahoo.com@groups.io> ha scritto:
John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt