Change storage Image rejection for mode to Image rejection for frequency

[PA3CCE]

I like the new IQ balance adjustment, now I can turn the image completely into the noise !

In the menu, storing of the IQ balance settings is provided for the different modes LSB, USB etc.

In my case, I find no- or neglectable differences in settings between the modes, but quite some difference in the settings over the entire frequency range. If confirmed, I should like to have the IQ balance in the menu per mode, changed to settings per frequency (Low-, medium-, High Frequency, or even better per band).

Jos (PA3CCE)

[df8oe]

Hello Jos,

this is a very good idea. When I first adjusted IQ with the new functions I had to increase power because I could not measure unwanted signal! And so I stated that there is a dependency to power, too. If you adjust it @0.5W and signal is completely gone, you switch to 5W and adjust that signal again is completely gone, then switch back to 0.5W you will see there is a slight misadjustment.

But we are talking about things which before nobody was able to see :)

We will think about improved structure, freuency dependency included. It is not high priority because now its working for the first time, but "good things can be improved" of course :)

vy 73 Andreas

[PA3CCE]

Well, I don't find the present situation real "good", when set at mid frequency, the image rejction at low- and high-frequencies are rather "poor"

73 de Jos

[df8oe]

...but much better than all the years before :) So I call it 100% "good". Hundreds of users have lived without a working IQ-adjustment and nearly nobody has complained before. But now, if it works - it is not good ??

Sorry - I cannot understand.

vy 73 Andreas

[PA3CCE]

A change from not working at all to 100% working for just one frequency is huge. Working for the entire frequency range is much better. I think that many users just calibrate for one frequency and think " OK fine". They seem not to be aware what happens at other frequencies. Besides, I never heard you say before that the image rejection was not working at all, or did I miss that ?

Best 73 de Jos

Op 8-4-2016 om 11:06 schreef eeDF8OE:

...but /much/ better than all ther years before :) So I call it 100% "good". Hundreds of users have lived without a working IQ-adjustment and nearly nobody has complained before. But now, if it works - it is /not good/ ??

Sorry - I cannot understand.

vy 73 Andreas

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-207338470

[df8oe]

Hello Jos,

haven't you read many posts in the past in Yahoo-NG that IQ-phase adjust does not work?? These posts go back to the time before I joined the project in May 2015... So the best adjustment in the past was not so good as if you adjust it with actual firmware and go to the band with the worst rejection. Because of it was not working properly before many users never have had adjusted their iq settings.

Additional problem may (again) be we reach edge of mcHF. The problem results of unsymmetrical capacities / inductivities at i and q LO signal line. I have already tested and they depend on many things like voltage of power supply, actual output etc. so it is possible that it is impossible to get all these dependencies included.

vy 73 Andreas

[PA3CCE]

Op 8-4-2016 om 16:06 schreef DF8OE:

Hello Jos,

haven't you read many posts in the past in Yahoo-NG that IQ-phase adjust does not work?? These posts go back to the time before I joined the project in May 2015... So the best adjustment in the past was not so good as if you adjust it with actual firmware and go to the band with the worst rejection. Because of it was not working properly before many users never have had adjusted their iq settings.

I agree, I also complained in the past. With me I could adjust the amplitude, but the phase adjustment did not react at all. However, this is'nt "not working at all". To my opinion this is not to be used as a reference to declare the present situation as "good".

Additional problem may (again) be we reach edge of mcHF. The problem results of unsymmetrical capacities / inductivities at i and q LO signal line. I have already tested and they depend on many things like voltage of power supply, actual output etc. so it is possible that it is impossible to get all these dependencies included.

Sure it will never be perfect, but what I proposed might be an acceptable approach. Do not underestimate the importance of the best image rejection in Tx- as well in Rx-mode.

73 de Jos

vy 73

Andreas

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-207445148

[DD4WH]

Hi Jos, hi Andreas, my impression is, we have all fully acknowledged that we need a smart solution for the dependencies of the phase adjustment in order to get the very best out of our hardware. But we should also be smart in using a slim solution, if it is feasible and appropriate. I am not sure whether a phase adjustment for every band would achieve this (and would be necessary), but we would probably need more data on that in order to be able to decide.

Could you two state the amount of sideband suppression that is lost when you adjust phase & amplitude perfectly for one band and then change to the band with the worst suppression? Is it in the range of 2-5dB or in the range of 10-20dB? And please also state whether your measurement is for TX or RX.

Theoretically, (for TX) if we can adjust sideband suppression to an optimum of 55dB for one band and this gets worse for another band in an order of 6dB, well, then don´t let us talk about that again . . ., that´s still 49dB of suppression (10W -49dB equals 126µW, which is acceptable in my view).

For RX, with listening to DX signals and a local 100W station at 12kHz of your frequency (if you use the 12k IF), it could be nice to have 6dB more suppresion . . . however, the best hardware phasing receivers hardly ever achieve more than 45dB of sideband suppression (in the best band!).

Let us look into the HARDWARE signal I&Q chain, this is different for TX and RX: RX: C68/C69 (22nF)--> they should be matched! I did that when I built the mcHF and I do not have such a big improvement with the new phase adjustment as others, maybe because of the matching, dont know!?
C71/C73 --> must be 0R ! C26/C31 (470nF) --> maybe matching helps? Have not tried yet C18/C19 (1µF) --> maybe matching helps? Have not tried yet --> For RX, it should be easy to match the three pairs and have very good sideband suppression with the hardware alone

TX: C7a/C8a (470nF) C7/C8 (470nF) C109-C112 (10µF) C114-C120 (100µF) C84-C87 (22nF) --> at least these must be matched! --> There are not so many capacitors and no inductor in the I&Q signal chain. So, I do not see that it would not be possible to improve a lot on the hardware side by matching the capacitors in the I&Q TX line.

Question 1: Maybe this also helps to decrease the frequency dependence of the phase adjustment?

Question 2: Is it necessary to distinguish between phase adjustment for LSB & USB, AM & FM? --> At least theoretically, I do not see any reason for this: All the demodulation steps occur in software. So, if we adjust I& Q phase and amplitude before demodulation (as is the case in the moment), this adjustment should be the same and should hold for ALL demodulation modes. (It would be good, however, if that could be supported by your observations!)

This could free up EEPROM and menu space for frequency dependent adjustments!? --> Just a thought . . .

added later: As comparisons of the mcHF and the KX3 seem fashionable at the moment (;-)), it is worth noting that the KX3 also has separate IQ phase adjustments entries for EACH band.

73 de Frank DD4WH

[PA3CCE]

Hi Frank,

First of all I must tell you that at this moment I cannot perform any test, since today my mchf stopt working. Something is wrong in my LO. At times the frequency display is in red color and the spetrum display is interrupted in abt 1 sec rate. When I change frequency, the spectrum display stops inmediately. Could not find the cause so far.

I also can tell you that I have made all modifications as they are in the circuits of IZ6MAF, so all unnecessary capacitors are shorted etc. I did the tests in Rx mode only. Further more I had matched the appropriate components in the demod circuit.

I can give you the adjustment figures below :

Freq LSB USB ampl/phase ampl/phase

3MHz 5/2 5/1 5MHz 11/5 11/4 7MHz 17/8 18/7 10MHz 19/14 20/13 14MHz 30/22 28/22 21MHz 50/38 54/37 24MHz 58/52 58/50 28MHz 63/65 63/65

These are the settings I found in the menu (all positive). You see that the difference between the demod modes are neglectable, this was the reason I did not test the other modes. You also can see large differences per frequency, in phase as well in amplitude. I did not write down the differences in image rejection but, since you know the change per step, you can have an idea.

As soon as I have mcHF working again I can profide you more info. I hope this helps.

best 73 de Jos

Op 8-4-2016 om 19:43 schreef DD4WH:

Hi Jos, hi Andreas, my impression is, we have all fully acknowledged that we need a smart solution for the dependencies of the phase adjustment in order to get the very best out of our hardware. But we should also be smart in using a slim solution, if it is feasible and appropriate. I am not sure whether a phase adjustment for every band would achieve this (and would be necessary), but we would probably need more data on that in order to be able to decide.

Could you two state the amount of sideband suppression that is lost when you adjust phase & amplitude perfectly for one band and then change to the band with the worst suppression? Is it in the range of 2-5dB or in the range of 10-20dB? And please also state whether your measurement is for TX or RX.

Theoretically, (for TX) if we can adjust sideband suppression to an optimum of 55dB for one band and this gets worse for another band in an order of 6dB, well, then don´t let us talk about that again . . ., that´s still 49dB of suppression (10W -49dB equals 126µW, which is acceptable in my view).

For RX, with listening to DX signals and a local 100W station at 12kHz of your frequency (if you use the 12k IF), it could be nice to have 6dB more suppresion . . . however, the best hardware phasing receivers hardly ever achieve more than 45dB of sideband suppression (in the best band!).

Let us look into the HARDWARE signal I&Q chain, this is different for TX and RX: RX: C68/C69 (22nF)--> they should be matched! I did that when I built the mcHF and I do not have such a big improvement with the new phase adjustment as others, maybe because of the matching, dont know!?

C71/C73 --> must be 0R ! C26/C31 (470nF) --> maybe matching helps? Have not tried yet C18/C19 (1µF) --> maybe matching helps? Have not tried yet --> For RX, it should be easy to match the three pairs and have very good sideband suppression with the hardware alone

TX: C7a/C8a (470nF) C7/C8 (470nF) C109-C112 (10µF) C114-C120 (100µF) C84-C87 (22nF) --> at least these must be matched! --> There are not so many capacitors and no inductor in the I&Q signal chain. So, I do not see that it would not be possible to improve a lot on the hardware side by matching the capacitors in the I&Q TX line.

Question 1: Maybe this also helps to decrease the frequency dependence of the phase adjustment?

Question 2: Is it necessary to distinguish between phase adjustment for LSB & USB, AM & FM? --> At least theoretically, I do not see any reason for this: All the demodulation steps occur in software. So, if we adjust I& Q phase and amplitude before demodulation (as is the case in the moment), this adjustment should be the same and should hold for ALL demodulation modes. (It would be good, however, if that could be supported by your observations!)

This could free up EEPROM and menu space for frequency dependent adjustments!? --> Just a thought . . .

73 de Frank DD4WH

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-207533110

[DD4WH]

Hi Jos,

thanks a lot for your data. That helps, also it would be very good to also have settings translated into dB of suppression ;-) I altered the setting of the finetuning a few versions of firmware ago, so a difference of 5 to 63 is not so big anymore as it was in former times ;-)

I had the same problem with red digits and it returns from time to time. Check soldering of the Si570 and around that, very likely that the problem is there, but Andreas probably knows more. From your data, I would conclude, we can stop distinguishing between modes in the phase and amplitude adjustment! Also, if you have matched capacitors in the Rx chain, it would have to be concluded that this does not help against the frequency dependance of the adjustments! Very interesting and valuable results. I will think about that and wait for more info from other users.

Thanks a lot for your info and good luck in fixing your rig! If it is ok, I would appreciate very much more info, eg. from TX mode and other measurements!

73 de Frank

[df8oe]

Hello Jos,

that is very interesting! My settings differ only +/- 2 (both phase and gain) between optimum and worst band.

Why does yours differ so much? Now I understnad your opinion - but I think, you do have a hardware problem. All of my 4 mcHFs differ only +/- 2...

y 73 Andreas

[PA3CCE]

Hello Andreas

+/- 2 difference over the entire frequency range, are you sure ? That is almost ideal, I can hardly believe that. I hope my mcHF will be operable soon, I ordered a new RF board, the old one is, due to many experiments, worn out.

best 73 de Jos

8-4-2016 om 23:58 schreef DF8OE:

Hello Jos,

that is very interesting! My settings differ only +/- 2 (both phase and gain) between optimum and worst band.

Why does yours differ so much? Now I understnad your opinion - but I think, you do have a hardware problem. All of my 4 mcHFs differ only +/- 2...

y 73 Andreas

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-207623279

[df8oe]

Yes. I have one mcHF built as RX-only and three mcHFs built as transceivers.

but I have made a modification on all of these which is not documented yet - maybe that is the reason??!!

I kicked off drivers U12 and U13 on rf-board and swapped R22...R25 with 0R. Drivers are producing more phase shifting at higher frequencies and in my eyes are not neccessary (and maybe they do disturb more than they are useful). But I have not made intensive measuring. Of course this can be the reason for the great differences between your mcHF and mine!

Must be investigated... But I am only one person and have to make business, too , so I do not have much time for all of this. McHF takes already big part of my time :)

vy 73 Andreas

[DD4WH]

Very impressive differences! Hmmm . . .

Andreas, is that in RX or TX or both? Are the differences between modes also so small?

Would love to try your mod, did you solder out the SN74LVC2G17s or did you just solder two wires on top of them to bridge the buffers?

73 de Frank

P.S.: Unfortunately, I am not able to measure myself, because I have no stable RF generator with such a high drive . . .

[df8oe]

You must desolder little drivers and connect in/out (2x at each driver) with wire. My settings are in a small range at RX and TX.

vy 73 Andreas

[PA3CCE]

@ Andreas, Frank,

OK Andreas that is most interesting information, thank you. As a matter of fact, the new RF board I ordered is of version 0.5. In this version these drivers are rejected indeed and the traces of the LO are matched for impedance, as described by Chris. As soon I have the results, I will let you both know.

Have a nice weekend, Jos

Op 9-4-2016 om 14:18 schreef DF8OE:

Yes. I have one mcHF built as RX-only and three mcHFs built as transceivers.

but I have made a modification on all of these which is not documented yet - maybe that is the reason??!!

I kicked off drivers U12 and U13 on rf-board and swapped R22...R25 with 0R. Drivers are producing more phase shifting at higher frequencies and in my eyes are not neccessary (and maybe they do disturb more than they are useful). But I have not made intensive measuring. Of course this can be the reason for the great differences between your mcHF and mine!

Must be investigated... But I am only one person and have to make business, too , so I do not have much time for all of this. McHF takes already big part of my time :)

vy 73 Andreas

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-207782390

[df8oe]

Hello Jos,

thank you for this information. That will be an explanation... Additional I have used 7474 manufactured by "Potatoe Chips" which has anupper working frequency of 1GHz. This will become eccessary when you will add the rf-mod-pcb so that 6m and 4m are available, too. Maybe timing at higher frequencies is more precise like on normal logic IC...

Your feedback after getting new pcbs is welcome!

Have a nice weekend, too Andreas

[PA3CCE]

Hi Andreas

Thanks again, I must have some "Potatoe Chips" circuits somewhere too, so I will see. I hope and expect theat I can keep using the UI version 0.4, for I just ordered the RF board.

Cheers Jos

Op 9-4-2016 om 16:11 schreef DF8OE:

Hello Jos,

thank you for this information. That will be an explanation... Additional I have used 7474 manufactured by "Potatoe Chips" which has anupper working frequency of 1GHz. This will become eccessary when you will add the rf-mod-pcb so that 6m and 4m are available, too. Maybe timing at higher frequencies is more precise like on normal logic IC...

Your feedback after getting new pcbs is welcome!

Have a nice weekend, too Andreas

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-207794299

[DD4WH]

Very interesting, these 7474 chips! Did you also use the faster potatoe version of the 3253 as substitutes for the 3253 Muxer? The potatoe version seems to have much larger on resistance (17-22ohms vs 3-6ohms), could potentially be a problem!

73 de Frank

[DD4WH]

I could now reactivate my Dipmeter and an RF amp and an attenuator, so I had an RF source at hand which produced a huge RF signal with -17dBm. Here are my settings for optimum IQ amplitude and phase adjustment setting for specific frequencies: (frequency, (ampl., phase for LSB), (ampl., phase for USB))

2.5MHz -14/-20 LSB -14/-20 USB 4MHz -13/-19 LSB -12/-19 USB 8MHz -13/-20 LSB -13/-20 USB 12MHz -20/-34 LSB -23/-23 USB 16MHz -16/-30 LSB -16/-27 USB 21MHz -24/-31 LSB -25/-29 USB 24MHz -34/-49 LSB -35/-44 USB 28MHz -37/-55 LSB -38/-46 USB

side observation: at 24MHz and 28MHz the nulling was dependent on where I put my fingers on the mcHF (which has no shielding or metal case in my mcHF)!!! That could also be one of the reasons for your varying results, Jos!?

My conclusions: 1.) we do not need to distinguish between LSB, USB, AM, SAM, FM in the amplitude & phase adjustments --> software can be simplified 2.) the adjustment is more or less frequency dependent (depends on your build/your measurement situation) --> whether we need a band-specific possibility to adjust, is not clear yet, because in my case (see above), it would really be overkill . . . but in others (Jos!) it could be nice to have. 3.) The frequency dependance is probably 100% the result of the buffer ICs U9, U12, and U13 (if you compare Andreas´ results with Jos´ and my results). The buffer ICs U9, U12, U13 and corresponding Rs R19, R22-R25 should be eliminated as a suggested modification.

Comments and more measurement data very welcome!

73 de Frank

[df8oe]

I do not have swapped mixers (due to quite different Ron what will be a problem). But I have tested nd they are usable up to 100MHz - they will work with 6m and 4m od, too.

vy73 Andreas

[PA3CCE]

Thanks, see below. Jos

Op 10-4-2016 om 13:09 schreef DD4WH:

I could now reactivate my Dipmeter and an RF amp and an attenuator, so I had an RF source at hand which produced a huge RF signal with -17dBm. Here are my settings for optimum IQ amplitude and phase adjustment setting for specific frequencies: (frequency, (ampl., phase for LSB), (ampl., phase for USB))

2.5MHz -14/-20 LSB -14/-20 USB 4MHz -13/-19 LSB -12/-19 USB 8MHz -13/-20 LSB -13/-20 USB 12MHz -20/-34 LSB -23/-23 USB 16MHz -16/-30 LSB -16/-27 USB 21MHz -24/-31 LSB -25/-29 USB 24MHz -34/-49 LSB -35/-44 USB 28MHz -37/-55 LSB -38/-46 USB

side observation: at 24MHz and 28MHz the nulling was dependent on where I put my fingers on the mcHF (which has no shielding or metal case in my mcHF)!!! That could also be one of the reasons for your varying results, Jos!?

Jos : I had a shield between RF board and UI board, but no metal case. Observed NO sensitivity to fingers placed on the mcHF, measurements were stable did not look for instabilities. My measurements were executed at approx. -40 dBm at antenna in. Had a RF preamp with PGA103+.

My conclusions: 1.) we do not need to distinguish between LSB, USB, AM, SAM, FM in the amplitude & phase adjustments --> software can be simplified

Jos: Agreed

2.) the adjustment is more or less frequency dependent (depends on your build/your measurement situation) --> whether we need a band-specific possibility to adjust, is not clear yet, because in my case (see above), it would really be overkill . . . but in others (Jos!) it could be nice to have.

Jos: Overkill ? , I don't know, what was your difference in image rejection between lowest/highest band when adjusted at mid band? Sorry I did not note down , as said I could adjust deep into the noise, so rejection was >>-60 dB. I prefer to have highest rejection as possible to avoid all kind of interference.

3.) The frequency dependance is probably 100% the result of the buffer ICs U9, U12, and U13 (if you compare Andreas´ results with Jos´ and my results). The buffer ICs U9, U12, U13 and corresponding Rs R19, R22-R25 should be eliminated as a suggested modification.

Jos: U12 and U13 were still in, corresponding Rs were out. I'm anxious to see the results of version 0.5 RF board. However, results may be dependent of many variables.

Comments and more measurement data very welcome!

Jos: Will do so when new version 0.5 RF board has arrived and built. When the LO modification solves this problem (more or less), there still must be a solution for version 0.4 users.

73 de Frank

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-207961383

[DD4WH]

I just soldered out U12 and U13 and put in 0R for R22-R25. So these buffers are now out of the I&Q path: Did the same measurements again for RX:

2.5MHz -10/-22 LSB -7/-22 USB 4MHz -11/-24 LSB -4/-23 USB 8MHz -3/-29 LSB 2/-28 USB 12MHz 2/-33 LSB 5/-33 USB 16MHz 11/-31 LSB 14/-31 USB 21MHz 4/-44 LSB 7/-43 USB 24MHz 5/-72 LSB 7/-72 USB 28MHz 33/-56 LSB 35/-56 USB

So, what would you conclude from this? Comments welcome! ;-) 73 de Frank

[DD4WH]

I would conclude that my measurements at 24/28MHz probably are not reliable, because the (very strong) signal of -17dBm seems to enter the mcHF over additional paths . . . However the other measurements seem to indicate the following:

@2.) we need a frequency dependent I&Q amplitude and phase adjustment. I fully agree with you, Jos, now with those measurements. A difference in adjustment of +-3 can result in a difference in mirror rejection of >20dB (not measured, but a sophisticated guess by me). Sometimes +2 steps turns absolute silence to a rather loud annoying heterodyne.

@3.) my hypothesis must be rejected: the buffers are not the problem! New hypothesis: the 74LCX74M (U11) is the problem, that chip seems to have a huge frequency dependence in handling amplitudes and phase. I will order the "wonder chip" (7474) by Potatoe chips in order to validate that. Andreas, could you confirm, it is this one, please: http://www.ebay.com/itm/7474-G-Series-GHz-TTL-CMOS-logic-IC-14pin-SOIC-QTY-1-/330551715157

73 de Frank

[df8oe]

YES - that is the one I am using.

vy 73 Andreas

[PA3CCE]

Op 10-4-2016 om 14:39 schreef DD4WH:

I would conclude that my measurements at 24/28MHz probably are not reliable, because the (very strong) signal of -17dBm seems to enter the mcHF over additional paths . . .

Might be, but see my findings also. Can't you make a simple attenuator of say 20dB or more ? OK, you are using a dipmeter, may radiate a lot :( 1 turn loop on a long cable ?

However the other measurements seem to indicate the following:

@2 https://github.com/2.) we need a frequency dependent I&Q amplitude and phase adjustment. I fully agree with you, Jos, now with those measurements. A difference in adjustment of +-3 can result in a difference in mirror rejection of >20dB (not measured, but a sophisticated guess by me). Sometimes +2 steps turns absolute silence to a rather loud annoying heterodyne.

This matches my findings, 1 step makes a difference of no tone to a noticeable tone. I also could make use of the S-meter, no signal was approx. S3 of noise. Signal input was S9 + 30 dB or so. I could calculate the approx. rejection 1 S-unit = 6dB

@3 https://github.com/3.) my hypothesis must be rejected: the buffers are not the problem!

Looks worse than better, but as said there are probable more variables, it's tricky.

New hypothesis: the 74LCX74M (U11) is the problem, that chip seems to have a huge frequency dependence in handling amplitudes and phase. I will order the "wonder chip" (7474) by Potatoe chips in order to validate that.

Andreas, could you confirm, it is this one, please: http://www.ebay.com/itm/7474-G-Series-GHz-TTL-CMOS-logic-IC-14pin-SOIC-QTY-1-/330551715157

73 de Frank

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-207979264

[DD4WH]

After some time for thinking, I have some new findings:

1.) With the buffers in my mcHF, there were no differences between LSB/USB. After taking out the buffer ICs, measuring, and after that additionally resoldering my solder bridges and measuring everything again, there are still significant differences between USB & LSB, but only in the amplitude adjustments, not in the phase adjustment! Thus, the buffers U12/U13 seem to be useful for eliminating frequency effects on the IQ amplitude differences. So, we do need software diiferentiation between LSB/USB adjustment, because RF board 0.5 has no more buffers.

2.) & 3.) Even IF the potatoe chip 7474 eliminates frequency dependancy, probably not every user will order it and build it in. So do we want a software adjustment? If yes, I would suggest: 12 different adjustments with the following low corner frequencies which I have chosen for ham radio use AND SWL in mind: 100kHz - 2200m 450kHz - 630m 1.75MHz - 160m 3MHz - 80m 5.5MHz - 40m 8MHz - 30m 11MHz - 20m 14.5MHz - BC 19m 16MHz - 17m 19MHz - 15m 22MHz - 12m 25MHz - 10m

12 adjustments for amplitude & phase for USB/LSB separately means 48 adjustments (and also 48 EEPROM memory places)!

73 de Frank

[df8oe]

After we got a working IQ-adjustment -and first at this point - we consider that there is huge hardware problem sleeping in design of PCB. Because of IQ-lines are not designed @50 ohms there are frequency dependencies which never were recognized before. Capacities of mixer inputs and output impedance of drivers (or of 7474) are involved, too.

I think before we start a huge storing orgy we first have to accumulate informations. Maybe it is possible to find a formula how better scalings can be calculated. But therefore we need much more samples of actually best IQ adjustments...

vy 73 Andreas

[DD4WH]

Yes, you are right, the new software now makes the hardest hardware tests possible for the first time!

And the few results are still not leading into one direction and hardware effects are complex.

So let us do more tests and gather more data under the diverse configurations.

I am really curious whether the 7474 chip from Potatoe chips will solve all that . . .

73 de Frank

[PA3CCE]

@Andreas, Frank

Just my penny :

1) I do NOT see the necessity of making difference in adjustment in
demodulation modes. dependency of other factors are many many times bigger. Besides, I have never seen this in other projects either.

2) I do NOT believe in one satisfactory adjustment for all frequencies (and on all existing mcHF variants) , there are too many dependencies involved ( trace impedances, stray capacitances, stray inductances, component variations, etc. etc.) .

Best compromise : Be realistic and make the best (simplest) solution for everyone, provide for an adjustment for each frequency band (maybe more for the highest frequencies), NOT regarding modulation mode.

Best 73 Jos

Op 10-4-2016 om 16:55 schreef DF8OE:

After we got a working IQ-adjustment -and first at this point - we consider that there is huge hardware problem sleeping in design of PCB. Because of IQ-lines are not designed @50 https://github.com/50 ohms there are frequency dependencies which never were recognized before. Capacities of mixer inputs and output impedance of drivers (or of 7474) are involved, too.

I think before we start a huge storing orgy we first have to accumulate informations. Maybe it is possible to find a formula how better scalings can be calculated. But therefore we need much more samples of actually best IQ adjustments...

vy 73 Andreas

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-207996178

[df8oe]

It is not trivial to implement so much storing (especially for users who don't have fitted serial EEPROM because in actual virtual EEPROM there is a cut at 383 words).

So let us "be patient" and find a solution.

Again: all these problems came up a few days ago when IQ adjustment works as fine as is is now....

I don't think it is a problem in waiting some more days (or weeks) for finding best compromise - problem exists from the birth of mcHF on!!!!

We are pointed on this and working on it to get best solution.

vy 73 Andreas

[PA3CCE]

It's your choise. How many stores do you have now, for all modulation modes ! When you find a better solution you can change any time.

Jos

Op 10-4-2016 om 18:49 schreef DF8OE:

It is not trivial to implement so much storing (especially for users who don't have fitted serial EEPROM because in actual virtual EEPROM there is a cut at 383 words).

So let us "be patient" and find a solution.

Again: all these problems came up a few days ago when IQ adjustment works as fine as is is now....

I don't think it is a problem in waiting some more days (or weeks) for finding best compromise - problem exists from the birth of mcHF on!!!!

We are pointed on this and working on it to get best solution.

vy 73 Andreas

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-208014339

[df8oe]

We don't have enough at the moment for users without serial EEPROM.

At the moment we do have 10 storage places. If we orientate in frequency only for HAM usage we need 12 and when we add some for SWLs we need 16.

vy 73 Andreas

[PA3CCE]

how do they cope now with all these modulation mode stores ? No argument, sorry.

Op 10-4-2016 om 19:00 schreef DF8OE:

We don't have enough at the moment for users without serial EEPROM.

vy 73 Andreas

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-208015514

[DD4WH]

Keep calm, guys ;-) Rome has not been built in a single day . . .

We have all understood the problem and the arguments now and now it is time to stop talking, to measure again, to think hard again for the best optimization (because we are talking about an already superb mirror rejection here --> in the early days of the SDR cube 25dB was called "very usable" and we have >60dB when propery adjusted!!!), and then to start programming with an economic view on the EEPROM storage room :-)

Have fun!

73 de Frank

[PA3CCE]

OK Frank,

No problems here, I just like real arguments ;) Will wait and see patiently what happens. Will let you guys know when I have more info.

Jos

Op 10-4-2016 om 19:23 schreef DD4WH:

Keep calm, guys ;-) Rome has not been built in a single day . . .

We have all understood the problem and the arguments now and now it is time to stop talking, to measure again, to think hard again for the best optimization (because we are talking about an already superb mirror rejection here --> in the early days of the SDR cube 25dB was called "very usable" and we have >60dB when propery adjusted!!!), and then to start programming with an economic view on the EEPROM storage room :-)

Have fun!

73 de Frank

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-208020447

[DG9BFC]

what about storing some set points and the mcu calculates the points in between??

say you have a point of phase /gain at 1 megs of 20/30 and another at 6 megs with 25/35 ...

and you find out that the gain and phase is almost linear over that range (means at 2 megs you need 21/31 and at 3 megs 22/32) ... then you just store a few rough set points ... and rest is done in a calculation step inside the mcu

if at lower or higher bands the phase and gain correction is not that linear ... then just spread in another set point .... guessing that with a few points an almost ideal curve can be stored ... without the need of a too high number of set points

[df8oe]

That's the idea we have had, too! But there exist many possible modifications (e.g. swap 7474 with "potatoe chip", leave uffers like in rev. 0.5 is, different mixers...) All of these will change frequency dependency of IQ lines. So we will start investigations next weeks and hope as many users as possible will participate. We will offer a spreadsheet where every users fills in his personal IQ settings for many frequencies and modes, added his hardware he uses. Then we hope we can see if a function exist and how to detect if there are different possibilities.

y 73 Andreas

[HB9LFU]

Hello Frank / Andreas and others,

thanks a lot Frank for sending me the link to the message about signal quality and using the tune button. With a real signal the spectrum is compeletely different and does not show these spurs.

However, there was one left close to the desired signal. But I could reduce it drastically with the IQ menu settings. On 80m -50 was ideal. On 10m -50 was fully indadequate, I had to crank the value up to almost +99. The value for 60m was also ok on 80 and 40m. Also 30 and 20m were fairly close, the same holds true for 17 and 15, as well as 12 and 10m.

vy73s Roger

[DD4WH]

Hello Roger,

nice to hear that the problem is solved now! The TUNE function is very nice, but it is not good for checking signal quality ;-)

And also the phase adjustment does solve many "problems". However, we will collect more data on that and Andreas is preparing a spreadsheet for structured data collection and it would be very nice if you (and many others!) could participate. It will be prepared in the next weeks and announced in the Sulingen forum.

Have fun with the mcHF!

73 de Frank DD4WH

2016-04-14 20:43 GMT+02:00 HB9LFU notifications@github.com:

Hello Frank / Andreas and others,

thanks a lot Frank for sending me the link to the message about signal quality and using the tune button. With a real signal the spectrum is compeletely different and does not show these spurs.

However, there was one left close the desired signal. But I could reduce it drastically with the IQ menu settings. On 80m -50 was ideal. On 10m -50 was fully indadequate, I had to crank the value up to almost +99. The value for 60m was also ok on 80 and 40m. Also 30 and 20m were fairly close, the same holds true for 17 and 15, as well as 12 and 10m.

vy73s Roger

— You are receiving this because you commented. Reply to this email directly or view it on GitHub https://github.com/df8oe/mchf-github/issues/233#issuecomment-210094072

---

Frank - DD4WH QTH - Dresden, Germany Rx/Ant remote - Perseus SDR & K9AY lowband antenna Rx/Ant local - Teensy SDR standalone homebrew ugly style Rx

& AAA-1 Bulgarian active Antenna with double loop

[HB9LFU]

Hello Andreas,

this eeprom is so cheap and it does not take an hour to open the case and solder an eeprom to the ui-board that this part should become a mandatory thing.

vy73s Roger

[PA3CCE]

Hello Andreas Please find below the I/Q balance settings I found for my new RF board version 0.5 :

Rx I/Q adjustment : (mirror inaudible)

Conditions : Vi = -50dBm @ 50E Rx Preamp = 5dB pad + BGA103+ LO divide by 4 (U11) = Potatochips PO74G74A mcHF UI board version 0.4 mcHF RF board version 0.5 All IZ6MAF modifications implemented. Firmware 1.1.0 / BL 1.0 (May 20.. 21:06:47 EST)

3.65MHz Amplitude :. ...USB..10.....LSB 10 Phase : ..........USB -15....LSB -14

5.250MHz Amplitude :.....USB..20.....LSB...18 Phase :..........USB.-14.....LSB .-10

7.10MHz Amplitude :......USB..22.....LSB..18 Phase : ...........USB.-11.....LSB...-8

10.10MHz Amplitude :.......USB..22....LSB..22 Phase :.............USB..-5.....LSB..-5

14.1 MHz Amplitude :......USB..35.....LSB.. 32 Phase :............USB...1......LSB....1

18.69MHz Amplitude :.....USB..42.....LSB..38 Phase :...........USB..15.....LSB..17

21.2 MHz Amplitude :.....USB..54.....LSB..53 Phase : ..........USB..16.....LSB..17

24.89 MHz Amplitude :.....USB..63.....LSB..61 Phase : ..........USB..22.....LSB..22

28.500 MHz Amplitude : .....USB..69.....LSB..69 Phase ;............USB..52.....LSB..52

Best 73 Jos

[db4ple]

Hi,

your measurements are great. It seems to me that there is almost no difference between USB and LSB settings. For those where there is a difference, can you live with the average between both settings? Would allow us to use just one set of settings.

What I can see is there might be some formula to calculate the variation across the frequency from the low frequency and high frequency value. Catch is, we would need more data to do validate that.

That would limit the number of calibration steps in order to get to a better working mcHF. And we could reuse the existing EEPROM Layout.

73 Danilo

[PA3CCE]

Hi Danilo, Sure I can live with the average between the settings for USB and LSB, these diferences are marginal. It would be nice if you are able to implement a formula for the variations by frequency, it would be a big improvement in mcHF's performance. Of course we need more information from other users to verify.

vy 73 Jos

[HB9LFU]

Hello Danilo,

is there not enough storage space to have a per band adjustment of these settings?

vy73s Roger

[df8oe]

There is. But we want to keep adjustment menu and procedure as easy as possible and would prefer not to dig through a huge number of settings.

vy 73 Andreas

[HB9LFU]

Hello Andreas,

then why not adjust 80-60-40, 30-20,17-15 and 12-10 together. This would simplify the process considerably. I do not believe it is a good idea to calculate some sort of curve for the whole range and for all the different sets of mcHFs with varying modification levels.

vy73s Roger

[PA3CCE]

Hi all

When a formula alone does not work, a combination of both band grouping and a formula might come close to the ideal.

73 de Jos

[df8oe]

We are thinking about all this possibilities. There are BC bands, too and we must find the best solution for all users. We must collect more data (TX, too) for 0.4 and 0.5 PCB and different modification stages so we can find final solution.

vy 73 Andreas

[PA3CCE]

I/Q adjustment for the HAM bands is a way of band grouping for the BC bands !

73 de Jos

[db4ple]

Maybe to clarify: Even a formula approach will need some device specific calibration values, in order to to calculate the intermediate values for the various frequencies.