Date   
Re: Harmonics and Relay Replacement

Gary Anderson
 

It would be cool if someone with a S.A. could prove / disprove the coupling theory, by testing the 400mA, 200mA, 150mA versions of the AXICOM P2 Relay Series :)
They are all the same maximum coupling spec.  There is no reason to use more power if there is no benefit (shock/vibration argument aside), especially if it is to be chosen in the factory BOM.

Very happy to see there is merit in relay choice at HF frequencies. https://groups.io/g/BITX20/message/55897

Rgds,
Gary
AG5TX

Re: Harmonics and Relay Replacement

MVS Sarma
 

Farhan jee, I suppose it is "Axicom" and not axion.
regards
sarma vu3zmv


On Wednesday, October 10, 2018, Ashhar Farhan <farhanbox@...> wrote:
Guys,
If someone else too can confirm this fix. We will start ordering axion relays from now on. - f

On Wed, 10 Oct 2018, 23:15 Jim Sheldon, <w0eb@...> wrote:
Yup, and after opening up one of the original relays that I removed from a V4 board in prep for putting new ones on (they should be here within the hour) it was extremely obvious that those relays were not designed with RF in mind.  There is no shielding of the relay coil at all and all the contacts are on movable arms that run parallel to each other and the full length of the relay as well as close to the relay coil itself.  The armature is mostly made of plastic so doesn't provide much (if any) shielding between the coil and the movable contact arms.  The movable arms are each made up of 2 parallel, approximately 2mm wide strips of metal that are separated in the middle of the top of the relay by about 1 mm.  (Pictures not possible as the relays were pretty much destroyed in the dissection.)  I believe the parallel arm construction was for current carrying capability (not needed in small signal RF relays) as the contacts are rated to 125V @ 60 watts (their designation) in the data sheet.  The width & placement of these contact arms would allow a whole lot of coupling between both sets of contacts and I really believe it's one of the culprits though not necessarily the entire problem.  

Changing the relays to an RF rated set with proper isolation certainly can't hurt and may just wind up being the simplest fix for the problem.

The Postman just delivered the new relays from Digi-Key so off to install them and run some tests to see if I can prove or disprove Mike Doty's data.  

I do believe my results will corroborate his after chopping up one of the old relays to see what was in it.

Jim Sheldon


------ Original Message ------
From: "Arv Evans" <arvid.evans@...>
Sent: 10/10/2018 12:20:51 PM
Subject: Re: [BITX20] Harmonics and Relay Replacement

Jim

Sorry for the "blindly changing relays" comment.  That was not intended to be derogatorily in
any way.  Thinking when I said that was about those who follow what we say, assuming that
we have performed all the necessary testing and evaluation.  Some have measured the
capacitance between relay armatures and between relay contacts, but I have seen little
said about capacitance between RF carrying parts of these relays and the windings.  My
point was about the possibility of relay windings acting as RF chokes, thus allowing the DC
traces between relays to be coupling agents with respect to RF. 

Arv
_._


On Wed, Oct 10, 2018 at 11:02 AM Jim Sheldon <w0eb@...> wrote:
Arv and others,
#1 I really believe it's capacitive coupling within the relay itself and between the contacts, as well as from contacts to coil.  The original relays in the uBITX are inexpensive (read CHEAP) Chinese power relays that are not (I have their spec sheet) rated for RF and there are no RF parameters in their data sheet such as capacitance between contacts, from coil to armature and coil to contacts at all.  I had already bypassed the coil terminals to ground with .1uF SMD capacitors and didn't notice an appreciable difference.

#2, After this came to light, I don't consider myself "blindly" changing relays.  I'm investigating the cause and effect of changing these relays.  My two version 4 uBITX boards DO barely meet spec with the strongest harmonic(s) being -49 dB below the carrier level on MY (calibrated last year) spectrum analyzer.  Others' results will surely vary depending on the precision and how well and when calibrated their spectrum analyzers are.  I do not have the test equipment to measure inter contact/coil, etc. capacitance so I have no choice but change the relays as part of my experimentation.  It's an expense I am willing to undertake to attempt to improve MY uBITX rigs and if it helps others, so be it.  If others chose to ignore the results (good or bad) then the consequences are on them, not me as I am only sharing the information out there with the caveat "For What It's Worth!"  

Looking at the construction of the original relays after dissecting one, I can certainly see the wire to the far end of the coil runs parallel to the contacts along that same side of the relay and not very far away either.  Even though it's smaller than 30 gauge wire, the internal capacitance between the coil and at least one set of contacts is going to be a factor in these relays not to mention there is no shielding of the coil so inductance and capacitance could also be playing a part in the "blow-by".  

The new ones are too expensive to disect one as far as I'm concerned, but at least TE Products (Axicom) saw fit to publish the RF parameters (isolation by frequency) and inter contact/coil capacitance.  

Jim Sheldon, W0EB 





------ Original Message ------
From: "Arv Evans" <arvid.evans@...>
Sent: 10/10/2018 11:16:53 AM
Subject: Re: [BITX20] Harmonics and Relay Replacement

Kees, and others....

Blindly changing relays may fix the problem, but are we missing something here?
What is the real problem with the original relays?  Is it capacitive coupling between
RF carrying parts and the activation conductors, or is it that the relay coils might
be acting as RF chokes and allowing RF to be coupled between relays via the
RF-isolated traces of DC relay control leads?  Has anyone measured how much
is being carried by the DC control leads?  Has anyone tried bypassing the relay
control leads for RF?

Arv
_._


On Wed, Oct 10, 2018 at 8:56 AM Kees T <windy10605@...> wrote:
Thanks for dissecting an AXICOM relay and the pictures. The coil mounted over the contacts is a definite difference to the ones I dissected.

The other thing which may effect results is that most of the larger (16 pin) relays offer up to 4 different "coil sensitivity" options .....which will effect coil resistance and inductance. The resistance for a given 12V relay coil varies between about 960 ohms and about 320 ohms. That may well effect the coupling also.

I don't have enough different relays to compare but I do have some series inductors to evaluate. The thing to watch out for there is the inductor self resonance effect.

73 Kees K5BCQ

Re: Harmonics and Relay Replacement

Ashhar Farhan
 

Guys,
If someone else too can confirm this fix. We will start ordering axion relays from now on. - f

On Wed, 10 Oct 2018, 23:15 Jim Sheldon, <w0eb@...> wrote:
Yup, and after opening up one of the original relays that I removed from a V4 board in prep for putting new ones on (they should be here within the hour) it was extremely obvious that those relays were not designed with RF in mind.  There is no shielding of the relay coil at all and all the contacts are on movable arms that run parallel to each other and the full length of the relay as well as close to the relay coil itself.  The armature is mostly made of plastic so doesn't provide much (if any) shielding between the coil and the movable contact arms.  The movable arms are each made up of 2 parallel, approximately 2mm wide strips of metal that are separated in the middle of the top of the relay by about 1 mm.  (Pictures not possible as the relays were pretty much destroyed in the dissection.)  I believe the parallel arm construction was for current carrying capability (not needed in small signal RF relays) as the contacts are rated to 125V @ 60 watts (their designation) in the data sheet.  The width & placement of these contact arms would allow a whole lot of coupling between both sets of contacts and I really believe it's one of the culprits though not necessarily the entire problem.  

Changing the relays to an RF rated set with proper isolation certainly can't hurt and may just wind up being the simplest fix for the problem.

The Postman just delivered the new relays from Digi-Key so off to install them and run some tests to see if I can prove or disprove Mike Doty's data.  

I do believe my results will corroborate his after chopping up one of the old relays to see what was in it.

Jim Sheldon


------ Original Message ------
From: "Arv Evans" <arvid.evans@...>
Sent: 10/10/2018 12:20:51 PM
Subject: Re: [BITX20] Harmonics and Relay Replacement

Jim

Sorry for the "blindly changing relays" comment.  That was not intended to be derogatorily in
any way.  Thinking when I said that was about those who follow what we say, assuming that
we have performed all the necessary testing and evaluation.  Some have measured the
capacitance between relay armatures and between relay contacts, but I have seen little
said about capacitance between RF carrying parts of these relays and the windings.  My
point was about the possibility of relay windings acting as RF chokes, thus allowing the DC
traces between relays to be coupling agents with respect to RF. 

Arv
_._


On Wed, Oct 10, 2018 at 11:02 AM Jim Sheldon <w0eb@...> wrote:
Arv and others,
#1 I really believe it's capacitive coupling within the relay itself and between the contacts, as well as from contacts to coil.  The original relays in the uBITX are inexpensive (read CHEAP) Chinese power relays that are not (I have their spec sheet) rated for RF and there are no RF parameters in their data sheet such as capacitance between contacts, from coil to armature and coil to contacts at all.  I had already bypassed the coil terminals to ground with .1uF SMD capacitors and didn't notice an appreciable difference.

#2, After this came to light, I don't consider myself "blindly" changing relays.  I'm investigating the cause and effect of changing these relays.  My two version 4 uBITX boards DO barely meet spec with the strongest harmonic(s) being -49 dB below the carrier level on MY (calibrated last year) spectrum analyzer.  Others' results will surely vary depending on the precision and how well and when calibrated their spectrum analyzers are.  I do not have the test equipment to measure inter contact/coil, etc. capacitance so I have no choice but change the relays as part of my experimentation.  It's an expense I am willing to undertake to attempt to improve MY uBITX rigs and if it helps others, so be it.  If others chose to ignore the results (good or bad) then the consequences are on them, not me as I am only sharing the information out there with the caveat "For What It's Worth!"  

Looking at the construction of the original relays after dissecting one, I can certainly see the wire to the far end of the coil runs parallel to the contacts along that same side of the relay and not very far away either.  Even though it's smaller than 30 gauge wire, the internal capacitance between the coil and at least one set of contacts is going to be a factor in these relays not to mention there is no shielding of the coil so inductance and capacitance could also be playing a part in the "blow-by".  

The new ones are too expensive to disect one as far as I'm concerned, but at least TE Products (Axicom) saw fit to publish the RF parameters (isolation by frequency) and inter contact/coil capacitance.  

Jim Sheldon, W0EB 





------ Original Message ------
From: "Arv Evans" <arvid.evans@...>
Sent: 10/10/2018 11:16:53 AM
Subject: Re: [BITX20] Harmonics and Relay Replacement

Kees, and others....

Blindly changing relays may fix the problem, but are we missing something here?
What is the real problem with the original relays?  Is it capacitive coupling between
RF carrying parts and the activation conductors, or is it that the relay coils might
be acting as RF chokes and allowing RF to be coupled between relays via the
RF-isolated traces of DC relay control leads?  Has anyone measured how much
is being carried by the DC control leads?  Has anyone tried bypassing the relay
control leads for RF?

Arv
_._


On Wed, Oct 10, 2018 at 8:56 AM Kees T <windy10605@...> wrote:
Thanks for dissecting an AXICOM relay and the pictures. The coil mounted over the contacts is a definite difference to the ones I dissected.

The other thing which may effect results is that most of the larger (16 pin) relays offer up to 4 different "coil sensitivity" options .....which will effect coil resistance and inductance. The resistance for a given 12V relay coil varies between about 960 ohms and about 320 ohms. That may well effect the coupling also.

I don't have enough different relays to compare but I do have some series inductors to evaluate. The thing to watch out for there is the inductor self resonance effect.

73 Kees K5BCQ

Re: Harmonics and Relay Replacement

Jim Sheldon
 

Yup, and after opening up one of the original relays that I removed from a V4 board in prep for putting new ones on (they should be here within the hour) it was extremely obvious that those relays were not designed with RF in mind.  There is no shielding of the relay coil at all and all the contacts are on movable arms that run parallel to each other and the full length of the relay as well as close to the relay coil itself.  The armature is mostly made of plastic so doesn't provide much (if any) shielding between the coil and the movable contact arms.  The movable arms are each made up of 2 parallel, approximately 2mm wide strips of metal that are separated in the middle of the top of the relay by about 1 mm.  (Pictures not possible as the relays were pretty much destroyed in the dissection.)  I believe the parallel arm construction was for current carrying capability (not needed in small signal RF relays) as the contacts are rated to 125V @ 60 watts (their designation) in the data sheet.  The width & placement of these contact arms would allow a whole lot of coupling between both sets of contacts and I really believe it's one of the culprits though not necessarily the entire problem.  

Changing the relays to an RF rated set with proper isolation certainly can't hurt and may just wind up being the simplest fix for the problem.

The Postman just delivered the new relays from Digi-Key so off to install them and run some tests to see if I can prove or disprove Mike Doty's data.  

I do believe my results will corroborate his after chopping up one of the old relays to see what was in it.

Jim Sheldon


------ Original Message ------
From: "Arv Evans" <arvid.evans@...>
Sent: 10/10/2018 12:20:51 PM
Subject: Re: [BITX20] Harmonics and Relay Replacement

Jim

Sorry for the "blindly changing relays" comment.  That was not intended to be derogatorily in
any way.  Thinking when I said that was about those who follow what we say, assuming that
we have performed all the necessary testing and evaluation.  Some have measured the
capacitance between relay armatures and between relay contacts, but I have seen little
said about capacitance between RF carrying parts of these relays and the windings.  My
point was about the possibility of relay windings acting as RF chokes, thus allowing the DC
traces between relays to be coupling agents with respect to RF. 

Arv
_._


On Wed, Oct 10, 2018 at 11:02 AM Jim Sheldon <w0eb@...> wrote:
Arv and others,
#1 I really believe it's capacitive coupling within the relay itself and between the contacts, as well as from contacts to coil.  The original relays in the uBITX are inexpensive (read CHEAP) Chinese power relays that are not (I have their spec sheet) rated for RF and there are no RF parameters in their data sheet such as capacitance between contacts, from coil to armature and coil to contacts at all.  I had already bypassed the coil terminals to ground with .1uF SMD capacitors and didn't notice an appreciable difference.

#2, After this came to light, I don't consider myself "blindly" changing relays.  I'm investigating the cause and effect of changing these relays.  My two version 4 uBITX boards DO barely meet spec with the strongest harmonic(s) being -49 dB below the carrier level on MY (calibrated last year) spectrum analyzer.  Others' results will surely vary depending on the precision and how well and when calibrated their spectrum analyzers are.  I do not have the test equipment to measure inter contact/coil, etc. capacitance so I have no choice but change the relays as part of my experimentation.  It's an expense I am willing to undertake to attempt to improve MY uBITX rigs and if it helps others, so be it.  If others chose to ignore the results (good or bad) then the consequences are on them, not me as I am only sharing the information out there with the caveat "For What It's Worth!"  

Looking at the construction of the original relays after dissecting one, I can certainly see the wire to the far end of the coil runs parallel to the contacts along that same side of the relay and not very far away either.  Even though it's smaller than 30 gauge wire, the internal capacitance between the coil and at least one set of contacts is going to be a factor in these relays not to mention there is no shielding of the coil so inductance and capacitance could also be playing a part in the "blow-by".  

The new ones are too expensive to disect one as far as I'm concerned, but at least TE Products (Axicom) saw fit to publish the RF parameters (isolation by frequency) and inter contact/coil capacitance.  

Jim Sheldon, W0EB 





------ Original Message ------
From: "Arv Evans" <arvid.evans@...>
Sent: 10/10/2018 11:16:53 AM
Subject: Re: [BITX20] Harmonics and Relay Replacement

Kees, and others....

Blindly changing relays may fix the problem, but are we missing something here?
What is the real problem with the original relays?  Is it capacitive coupling between
RF carrying parts and the activation conductors, or is it that the relay coils might
be acting as RF chokes and allowing RF to be coupled between relays via the
RF-isolated traces of DC relay control leads?  Has anyone measured how much
is being carried by the DC control leads?  Has anyone tried bypassing the relay
control leads for RF?

Arv
_._


On Wed, Oct 10, 2018 at 8:56 AM Kees T <windy10605@...> wrote:
Thanks for dissecting an AXICOM relay and the pictures. The coil mounted over the contacts is a definite difference to the ones I dissected.

The other thing which may effect results is that most of the larger (16 pin) relays offer up to 4 different "coil sensitivity" options .....which will effect coil resistance and inductance. The resistance for a given 12V relay coil varies between about 960 ohms and about 320 ohms. That may well effect the coupling also.

I don't have enough different relays to compare but I do have some series inductors to evaluate. The thing to watch out for there is the inductor self resonance effect.

73 Kees K5BCQ

Re: Received modulation is good only if IFS is 1400-1810

Jerry Gaffke
 

See post   https://groups.io/g/BITX20/message/44278
for code to correctly compensate for an variation in the center of the 12mhz and 45mhz filters.

Also post  https://groups.io/g/BITX20/message/44515
for background on what's going on here.

While you are at it, perhaps 32628,32630 and 35235
for techniques to measure filter passband, and to properly calibrate the si5351.

There are a bunch of different firmware releases for the uBitx out there.
I have no idea if any of these techniques found there way into released code.
I do have my own body of code here, the above stuff does work.
Though I have not gotten around to plotting filter passbands yet.

Jerry, KE7ER




On Wed, Oct 10, 2018 at 10:02 AM, <andrea@...> wrote:
The current oscillator (CEC version) code looks as shown below. This code does not figure out compensation for crystal filters that have a shifted pass-band. I am suggesting to add a correction factor in the code that will allow the user to set an IF_FILTER_DEVIATION value (stored in the EEPROM) that will correct for IF Filter pass-band center, deviation from the norm.
 

Re: Harmonics and Relay Replacement

Arv Evans
 

Jim

Sorry for the "blindly changing relays" comment.  That was not intended to be derogatorily in
any way.  Thinking when I said that was about those who follow what we say, assuming that
we have performed all the necessary testing and evaluation.  Some have measured the
capacitance between relay armatures and between relay contacts, but I have seen little
said about capacitance between RF carrying parts of these relays and the windings.  My
point was about the possibility of relay windings acting as RF chokes, thus allowing the DC
traces between relays to be coupling agents with respect to RF. 

Arv
_._


On Wed, Oct 10, 2018 at 11:02 AM Jim Sheldon <w0eb@...> wrote:
Arv and others,
#1 I really believe it's capacitive coupling within the relay itself and between the contacts, as well as from contacts to coil.  The original relays in the uBITX are inexpensive (read CHEAP) Chinese power relays that are not (I have their spec sheet) rated for RF and there are no RF parameters in their data sheet such as capacitance between contacts, from coil to armature and coil to contacts at all.  I had already bypassed the coil terminals to ground with .1uF SMD capacitors and didn't notice an appreciable difference.

#2, After this came to light, I don't consider myself "blindly" changing relays.  I'm investigating the cause and effect of changing these relays.  My two version 4 uBITX boards DO barely meet spec with the strongest harmonic(s) being -49 dB below the carrier level on MY (calibrated last year) spectrum analyzer.  Others' results will surely vary depending on the precision and how well and when calibrated their spectrum analyzers are.  I do not have the test equipment to measure inter contact/coil, etc. capacitance so I have no choice but change the relays as part of my experimentation.  It's an expense I am willing to undertake to attempt to improve MY uBITX rigs and if it helps others, so be it.  If others chose to ignore the results (good or bad) then the consequences are on them, not me as I am only sharing the information out there with the caveat "For What It's Worth!"  

Looking at the construction of the original relays after dissecting one, I can certainly see the wire to the far end of the coil runs parallel to the contacts along that same side of the relay and not very far away either.  Even though it's smaller than 30 gauge wire, the internal capacitance between the coil and at least one set of contacts is going to be a factor in these relays not to mention there is no shielding of the coil so inductance and capacitance could also be playing a part in the "blow-by".  

The new ones are too expensive to disect one as far as I'm concerned, but at least TE Products (Axicom) saw fit to publish the RF parameters (isolation by frequency) and inter contact/coil capacitance.  

Jim Sheldon, W0EB 





------ Original Message ------
From: "Arv Evans" <arvid.evans@...>
Sent: 10/10/2018 11:16:53 AM
Subject: Re: [BITX20] Harmonics and Relay Replacement

Kees, and others....

Blindly changing relays may fix the problem, but are we missing something here?
What is the real problem with the original relays?  Is it capacitive coupling between
RF carrying parts and the activation conductors, or is it that the relay coils might
be acting as RF chokes and allowing RF to be coupled between relays via the
RF-isolated traces of DC relay control leads?  Has anyone measured how much
is being carried by the DC control leads?  Has anyone tried bypassing the relay
control leads for RF?

Arv
_._


On Wed, Oct 10, 2018 at 8:56 AM Kees T <windy10605@...> wrote:
Thanks for dissecting an AXICOM relay and the pictures. The coil mounted over the contacts is a definite difference to the ones I dissected.

The other thing which may effect results is that most of the larger (16 pin) relays offer up to 4 different "coil sensitivity" options .....which will effect coil resistance and inductance. The resistance for a given 12V relay coil varies between about 960 ohms and about 320 ohms. That may well effect the coupling also.

I don't have enough different relays to compare but I do have some series inductors to evaluate. The thing to watch out for there is the inductor self resonance effect.

73 Kees K5BCQ

Re: Harmonics and Relay Replacement

Jim Sheldon
 

Arv and others,
#1 I really believe it's capacitive coupling within the relay itself and between the contacts, as well as from contacts to coil.  The original relays in the uBITX are inexpensive (read CHEAP) Chinese power relays that are not (I have their spec sheet) rated for RF and there are no RF parameters in their data sheet such as capacitance between contacts, from coil to armature and coil to contacts at all.  I had already bypassed the coil terminals to ground with .1uF SMD capacitors and didn't notice an appreciable difference.

#2, After this came to light, I don't consider myself "blindly" changing relays.  I'm investigating the cause and effect of changing these relays.  My two version 4 uBITX boards DO barely meet spec with the strongest harmonic(s) being -49 dB below the carrier level on MY (calibrated last year) spectrum analyzer.  Others' results will surely vary depending on the precision and how well and when calibrated their spectrum analyzers are.  I do not have the test equipment to measure inter contact/coil, etc. capacitance so I have no choice but change the relays as part of my experimentation.  It's an expense I am willing to undertake to attempt to improve MY uBITX rigs and if it helps others, so be it.  If others chose to ignore the results (good or bad) then the consequences are on them, not me as I am only sharing the information out there with the caveat "For What It's Worth!"  

Looking at the construction of the original relays after dissecting one, I can certainly see the wire to the far end of the coil runs parallel to the contacts along that same side of the relay and not very far away either.  Even though it's smaller than 30 gauge wire, the internal capacitance between the coil and at least one set of contacts is going to be a factor in these relays not to mention there is no shielding of the coil so inductance and capacitance could also be playing a part in the "blow-by".  

The new ones are too expensive to disect one as far as I'm concerned, but at least TE Products (Axicom) saw fit to publish the RF parameters (isolation by frequency) and inter contact/coil capacitance.  

Jim Sheldon, W0EB 





------ Original Message ------
From: "Arv Evans" <arvid.evans@...>
Sent: 10/10/2018 11:16:53 AM
Subject: Re: [BITX20] Harmonics and Relay Replacement

Kees, and others....

Blindly changing relays may fix the problem, but are we missing something here?
What is the real problem with the original relays?  Is it capacitive coupling between
RF carrying parts and the activation conductors, or is it that the relay coils might
be acting as RF chokes and allowing RF to be coupled between relays via the
RF-isolated traces of DC relay control leads?  Has anyone measured how much
is being carried by the DC control leads?  Has anyone tried bypassing the relay
control leads for RF?

Arv
_._


On Wed, Oct 10, 2018 at 8:56 AM Kees T <windy10605@...> wrote:
Thanks for dissecting an AXICOM relay and the pictures. The coil mounted over the contacts is a definite difference to the ones I dissected.

The other thing which may effect results is that most of the larger (16 pin) relays offer up to 4 different "coil sensitivity" options .....which will effect coil resistance and inductance. The resistance for a given 12V relay coil varies between about 960 ohms and about 320 ohms. That may well effect the coupling also.

I don't have enough different relays to compare but I do have some series inductors to evaluate. The thing to watch out for there is the inductor self resonance effect.

73 Kees K5BCQ

Re: Received modulation is good only if IFS is 1400-1810

andrea@...
 

On Mon, Oct 8, 2018 at 07:34 PM, Dr. Flywheel wrote:
Individual component behavior can vary circuit response curve. This is a known fact and a proper design typically includes measures to compensate for statistical deviation from the norm. In the case of the V4 audio, I am getting very good audio output, once I took care of VFO and BFO calibration and then set the IF SHIFT to 2500 Hz. My audio circuits are not modified from the original design for the V4 audio (which does not use the TDA IC). In the long run I intend to change the software (very slightly) by an IF_CALIBRATION value (in my case 2500) to the code statement that set the oscillator. This would set my oscillator frequency to fall in the middle of the crystal filter pass-band, rather than on the sideline. When the oscillator frequency falls on the crystal filter side line, part of the audio spectrum is cut off very sharply (in my case the low frequencies on LSB) and in addition, the received signals are also severely attenuated.
 
Note that the symptoms that I a describing are not the same as the problem that Raj is suggesting to fix. The audio amplifier clipping problem can still exist for some of you and I suggest to fix them per Raj's suggestions, after you verified your VFO, BFO and IF SHIFT setting is close to optimal.
 
The current oscillator (CEC version) code looks as shown below. This code does not figure out compensation for crystal filters that have a shifted pass-band. I am suggesting to add a correction factor in the code that will allow the user to set an IF_FILTER_DEVIATION value (stored in the EEPROM) that will correct for IF Filter pass-band center, deviation from the norm.
 
void SetCarrierFreq()
{
  unsigned long appliedCarrier = ((cwMode == 0 ? usbCarrier : cwmCarrier) + (isIFShift && (inTx == 0) ? ifShiftValue : 0));
  //si5351bx_setfreq(0, (sdrModeOn ? 0 : appliedCarrier));
  si5351bx_setfreq(0, ((sdrModeOn && (inTx == 0)) ? 0 : appliedCarrier)); //found bug by KG4GEK
  
    /*
  if (cwMode == 0)
    si5351bx_setfreq(0, usbCarrier + (isIFShift ? ifShiftValue : 0));
  else
    si5351bx_setfreq(0, cwmCarrier + (isIFShift ? ifShiftValue : 0));
    */
}
 
--Ron    N7FTZ 

On Mon, Oct 8, 2018 at 4:34 AM Raj vu2zap <rajendrakumargg@...> wrote:
Please do the audio quiescent current mod that I have suggested in this group.
The low volume distortion makes the background hiss to sound like crackling.

Raj

P.S the relevant bits are left trailing.. (someone asked about what it relevant bits)

At 08-10-18, you wrote:

On mine uBitx there is a constant noise, somewhat crackling like a meat frying on a pan, that on the spectrum looks like a bump with peak around 2.5 or maybe 3 kHz. I can shift it with IF shift, but never loose it. I tried decoding FT8 and it goes quite well even if under this bump. SSB is hard to understand though, and only putting IF at 1600 makes it somewhat clearer. I can read very strong signals, but weaker are no-go.

Oh and my current stored IF shift is 0, if I read the dump correctly.

It seems a good idea.

 

Re: Harmonics and Relay Replacement

Arv Evans
 

Kees, and others....

Blindly changing relays may fix the problem, but are we missing something here?
What is the real problem with the original relays?  Is it capacitive coupling between
RF carrying parts and the activation conductors, or is it that the relay coils might
be acting as RF chokes and allowing RF to be coupled between relays via the
RF-isolated traces of DC relay control leads?  Has anyone measured how much
is being carried by the DC control leads?  Has anyone tried bypassing the relay
control leads for RF?

Arv
_._


On Wed, Oct 10, 2018 at 8:56 AM Kees T <windy10605@...> wrote:
Thanks for dissecting an AXICOM relay and the pictures. The coil mounted over the contacts is a definite difference to the ones I dissected.

The other thing which may effect results is that most of the larger (16 pin) relays offer up to 4 different "coil sensitivity" options .....which will effect coil resistance and inductance. The resistance for a given 12V relay coil varies between about 960 ohms and about 320 ohms. That may well effect the coupling also.

I don't have enough different relays to compare but I do have some series inductors to evaluate. The thing to watch out for there is the inductor self resonance effect.

73 Kees K5BCQ

Re: Simpler spur fix

ohwenzelph
 

I like this, but...

looks like you left C215 in but took C211 out of the circuit, does it matter? Maybe not..
are you sure they are Murata? Are they shielded? Probably not exactly 1206, maybe 1210.
does shielding matter, does the self resonant frequency matter? If it works, I just want to be able to duplicate it!
thanks so much

Re: Harmonics and Relay Replacement

Vince Vielhaber
 

When did Arrow start the free shipping? Last time I ordered from them, a couple of molex connectors - male and female, they charged me a couple of bucks each for the connectors, plus $18 shipping. But wait! There's more! The male connectors came from one warehouse and the female ones came from another - another $18 shipping!! I hadn't looked at them since for anything. And the shipping wasn't even overnite.

Vince.

On 10/10/2018 10:07 AM, Michael Maiorana wrote:
For those in the USA, you can order these from Arrow electronics
(arrow.com <http://arrow.com>). They are a little cheaper, plus you get
free overnight shipping.
I ordered some and will try to replicate Mike's results.
Mike M.
KU4QO

On Mon, Oct 8, 2018 at 3:54 PM Mike Doty via Groups.Io
<mikedoty=reagan.com@groups.io <mailto:reagan.com@groups.io>> wrote:

I thought I would pass this along, for whatever it is worth. I have
two Ver 3 and one Ver 4 uBiTX rigs. I have replaced K3, KT1, KT2,
and KT3 relays with Axicom relays which has knocked down the 3rd,
5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs
without any board modifications to the LPF circuits. This may be
anecdotal but with 3 rigs showing the same results it may be
something to consider. I purchased the relays from Mouser - part #
655-V23105A5403A201. Cost was $2.89 per relay plus shipping. I've
attached photos (sorry for the blurriness) showing the before and
after results on my Ver 4 rig.
--73-- Mike -- W0MNE

Re: Simpler spur fix

 

Mike, this works fine without bending too much to fit. I put them where I thought the issue would be fixed.
The 0.1uFs are redundant as there is no DC around that area.

Raj

At 10-10-18, you wrote:
Nice work Raj. Looking at the photo it appears that you have the L7 smt coil connected between T4 and Y1, eliminating C211. Is this correct or should the replacement coil connect between T4 and C211?
--73-- Mike

Re: Simpler spur fix

Jerry Gaffke
 

Good job, Raj!
That's looking like a very easy spur fix.

The 680nH inductors in your photo are larger than the adjacent 1206 parts in your photo.
But I'd bet 1206 inductors will do just fine.

Your photo shows that the SMD inductor replacing L7 is going around C211.
I doubt there's an issue with this, since the mixer should not have any DC there,
Anyone see a reason not to do this?.
Avoiding the C211 traces is a good thing.

Note that C210 and C216 are not stuffed in a stock uBitx (schematic says 0pF). 
Raj has left them unstuffed.

Jerry, KE7ER


On Wed, Oct 10, 2018 at 04:47 AM, Raj vu2zap showed a photo of his mods

On Wed, Oct 10, 2018 at 12:06 AM, Raj vu2zap wrote:
I found good reduction of spurs with the following mods:
1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid
2. Replace L7 as above.
The 45MHz filter is not required and you get almost the same power out as stock boards.
If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.
I used what I remember buying Murata inductors 1206 size.


Re: Simpler spur fix

Mike Doty
 

Nice work Raj.  Looking at the photo it appears that you have the L7 smt coil connected between T4 and Y1, eliminating C211.  Is this correct or should the replacement coil connect between T4 and C211?
--73-- Mike

Re: Harmonics and Relay Replacement

Kees T
 

Thanks for dissecting an AXICOM relay and the pictures. The coil mounted over the contacts is a definite difference to the ones I dissected.

The other thing which may effect results is that most of the larger (16 pin) relays offer up to 4 different "coil sensitivity" options .....which will effect coil resistance and inductance. The resistance for a given 12V relay coil varies between about 960 ohms and about 320 ohms. That may well effect the coupling also.

I don't have enough different relays to compare but I do have some series inductors to evaluate. The thing to watch out for there is the inductor self resonance effect.

73 Kees K5BCQ

Re: Harmonics and Relay Replacement

Jim Sheldon
 

Thanks Mike,
Ordered 10 of them from Arrow - even cheaper than Digi-Key by a couple of bucks and certainly much cheaper on the shipping with Arrow's free overnight shipping.

My Digi-Key order will be here in about an hour and I'll mod the two V4 boards I have.  After the Arrow order arrives tomorrow, I'll mod the 2 V3 boards and run the Spectrum tests on them.

Jim Sheldon, W0EB

------ Original Message ------
From: "Michael Maiorana" <zfreak@...>
Sent: 10/10/2018 9:07:12 AM
Subject: Re: [BITX20] Harmonics and Relay Replacement

For those in the USA, you can order these from Arrow electronics (arrow.com). They are a little cheaper, plus you get free overnight shipping.
I ordered some and will try to replicate Mike's results.
Mike M.
KU4QO

On Mon, Oct 8, 2018 at 3:54 PM Mike Doty via Groups.Io <mikedoty=reagan.com@groups.io> wrote:
I thought I would pass this along, for whatever it is worth.  I have two Ver 3 and one Ver 4 uBiTX rigs.  I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.  This may be anecdotal but with 3 rigs showing the same results it may be something to consider.  I purchased the relays from Mouser - part # 655-V23105A5403A201.  Cost was $2.89 per relay plus shipping.  I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.
--73--  Mike  --  W0MNE

Re: Harmonics and Relay Replacement

Michael Maiorana
 

For those in the USA, you can order these from Arrow electronics (arrow.com). They are a little cheaper, plus you get free overnight shipping.
I ordered some and will try to replicate Mike's results.
Mike M.
KU4QO

On Mon, Oct 8, 2018 at 3:54 PM Mike Doty via Groups.Io <mikedoty=reagan.com@groups.io> wrote:
I thought I would pass this along, for whatever it is worth.  I have two Ver 3 and one Ver 4 uBiTX rigs.  I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.  This may be anecdotal but with 3 rigs showing the same results it may be something to consider.  I purchased the relays from Mouser - part # 655-V23105A5403A201.  Cost was $2.89 per relay plus shipping.  I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.
--73--  Mike  --  W0MNE

Re: Simpler spur fix

iz oos
 

Thanks a lot!


Il 10/ott/2018 13:47, "Raj vu2zap" <rajendrakumargg@...> ha scritto:
Emacs!

At 10-10-18, you wrote:

Raj, can you show with a picture how you mounted L5 or L7, just to be double sure how to do that.

Il 10/ott/2018 10:25, "Raj vu2zap" < rajendrakumargg@...> ha scritto:
Oos it is!

Let us know your results.

When I checked many boards the spurs very higher in some than others. I discovered that the
physical position of L5 made a difference. Least spurs when vertical and more when horizontal.
Assumed that the tx signal was getting into the input of the BiDi amp. Better to stop at the input
and than amplify it and then filter it. 4 pole at Y1 did not matter at all but replacing L5 with SMD made
a big difference. There is an opinion that it must be ringing and SMD lower Q coil had made
the change!

I'll be back after 10-14 days at the farm, hope by then some of new relays will arrive for testing Mikes
relay fix.

Raj

At 10-10-18, you wrote:

Thanks Raj, very much appreciated! I will have to do this mod then which does not jeopardise the output power!

Il 10/ott/2018 09:06, "Raj vu2zap" < rajendrakumargg@...> ha scritto:
I found good reduction of spurs with the following mods:
1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid
2. Replace L7 as above.
The 45MHz filter is not required and you get almost the same power out as stock boards.
If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.
I used what I remember buying Murata inductors 1206 size.
Feed back will be appreciated.
With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.

Re: µBITX v3 : TX OK but no audio on RX

 

Sorry I just committed a right royal FU.

I was looking at V4 schematic and you are working with V3 - pins are different.

M1 and M2 is pis 3 & 5 and should have no connection at RX to pin 1.

If relay is OK, Check continuity from relay 3,5 to volume control top
and it should read 10 ohms.

Raj

At 10-10-18, you wrote:
Raj : D8 and pin 2 OK. I should learn again to read schematics, HI !
The problem now is pin 16 in contact with 14 and 12...

iz oos : Voltage is OK On the TDA . I didn't check it yet on Q70

Thanks for helping !

Re: Simpler spur fix

 

Emacs!

At 10-10-18, you wrote:

Raj, can you show with a picture how you mounted L5 or L7, just to be double sure how to do that.

Il 10/ott/2018 10:25, "Raj vu2zap" < rajendrakumargg@...> ha scritto:
Oos it is!

Let us know your results.

When I checked many boards the spurs very higher in some than others. I discovered that the
physical position of L5 made a difference. Least spurs when vertical and more when horizontal.
Assumed that the tx signal was getting into the input of the BiDi amp. Better to stop at the input
and than amplify it and then filter it. 4 pole at Y1 did not matter at all but replacing L5 with SMD made
a big difference. There is an opinion that it must be ringing and SMD lower Q coil had made
the change!

I'll be back after 10-14 days at the farm, hope by then some of new relays will arrive for testing Mikes
relay fix.

Raj

At 10-10-18, you wrote:

Thanks Raj, very much appreciated! I will have to do this mod then which does not jeopardise the output power!

Il 10/ott/2018 09:06, "Raj vu2zap" < rajendrakumargg@...> ha scritto:
I found good reduction of spurs with the following mods:
1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid
2. Replace L7 as above.
The 45MHz filter is not required and you get almost the same power out as stock boards.
If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.
I used what I remember buying Murata inductors 1206 size.
Feed back will be appreciated.
With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.