Topics

uBITx v5 - with mods

Ravi Miranda
 

Hi All,

Apologies for the long post.

Background
I built a V5 using the circuit here:
http://www.hfsignals.com/wp-content/uploads/2019/02/ubitx_v5.pdf

I have also included the mods (BFR106) and changed the resistors as
specified. Only the RX stage has been enabled.
For the stages I used :
http://w7zoi.net/bidirectional_matched_amplifier.pdf keeping the
original values intact

The ladder crystal filter has been built with 11.0592 Mhz Crystals.

The voltages for the RX side (only) transistors are as follows:
Q10 [C] (9.33) [B] (2.02) [E] (1.31)
Q11 [C] (11.69) [B] (9.33) [E] (8.62)
Q12 [C] (11.69) [B] (8.62) [E] (7.89)


Q30 [C] (9.12) [B] (2.06) [E] (1.38)
Q31 [C] (11.69) [B] (9.12) [E] (8.45)
Q32 [C] (11.69) [B] (8.45) [E] (7.75)

I have not used the AGC circuit as given in the original V5 but opted
for the LM324 version. However, this is not enabled.

I have taken the Panadapter out from just before the ladder filter
(post the stage 2 TIA). This is connected to SDRSharp to check signals

For the software, I used the V1.2 with frequencies calculated based on KD8CEC:
http://www.hamskey.com/2019/02/whats-new-with-ubitx-v5-1-changed-if.html

I used the following values:
#define SECOND_OSC_USB (56054200l)
#define SECOND_OSC_LSB (33940800l)

#define INIT_USB_FREQ (11059250l)

According to the notes in KD8CEC's blog the firstIF has been set to
45005000L due to L7 and L5 pulling the crystal filter by 5KHz

Using the PanAdapter tap point that has been provided for I can see
that the signal passes through at just about 45.000.000 MHz, but at
times (start up) the signal can be heard on SDR# on 44.993.400.


Going backwards, I have used a signal injector from the input of the
audio amp to the output of the crystal stage and have a good noise
injection level at the speaker. If I use the signal injector at the
input side of crystal filter there is no sound.

I am using a local MW station on 1458KHz as this is the only station
that I can hear via SDR# (AM). The beat seems correct.

I can hear this station on the uBITx speaker very faintly (if I put my
ear next to it).

I am unable to copy any Ham stations or WWV or any other HF broadcast stations.

On start up I can hear a slight crackling noise through the speaker,
but have no clue where this is being generated.

To ensure that the SI5351 was calibrated correctly I used :
https://groups.io/g/BITX20/wiki/Si5351-Calibration-Sketch

and saved the value in the program

I have a RF milivoltmeter (homebrew) using a AD8307 and LM358
(uncalibrated), this is showing signal levels at testpoints. I haven't
done a thorough test at all points yet.

I have injected a 20mV(approx) using a AD9851 into the antenna input I
can hear the zero beat (14.150). With a stronger signal injection the
speaker jumps around quite a bit :-)

I have the following few questions ( few)
1. How do I know that the uBITx is tuned correctly
2. The volume level through the speaker is very poor.
3. Are the voltage levels on the transistors correct?
4. Shouldn't the Pandadapter (RTL dongle + SDR#) show the spectrum of
a larger bandwidth rather than just the tuned frequency at 45MHz?
5. Are the stages amplifying correctly?
6. How do I locate the source of the crackling? This dies down in a few mins.

I have access to a DSO, what checks can I do to verify the working and
improve the sound level?

Thoughts suggestions and comments welcome.

Sorry once again for the long post and thanks for reading. Have a great weekend.

Best 73,

Ravi/M0RVI










--
I'm here to add more value to the world than I'm using up.

MVS Sarma
 

Ravi jee, 
Just use kd8cec , select the lcd type in ubitx.h, select ver5 on main file, just compile. 

Later pwer on Nd while calibrating  change bfo to 1105550 and click ptt and save. Also power cycle.
Later select wwv and complete calibration.if needed few steps of bfo.

You should succeed. Atb
Sarma vu3 zmv



On Sat, 8 Jun 2019, 8:14 pm Ravi Miranda <ravimiranda@... wrote:
Hi All,

Apologies for the long post.

Background
I built a V5 using the circuit here:
http://www.hfsignals.com/wp-content/uploads/2019/02/ubitx_v5.pdf

I have also included the mods (BFR106) and changed the resistors as
specified. Only the RX stage has been enabled.
For the stages I used :
http://w7zoi.net/bidirectional_matched_amplifier.pdf keeping the
original values intact

The ladder crystal filter has been built with 11.0592 Mhz Crystals.

The voltages for the RX side (only) transistors are as follows:
Q10 [C] (9.33)     [B] (2.02)      [E] (1.31)
Q11 [C] (11.69)    [B] (9.33)     [E] (8.62)
Q12 [C] (11.69)    [B] (8.62)     [E] (7.89)


Q30 [C] (9.12)     [B] (2.06)      [E] (1.38)
Q31 [C] (11.69)    [B] (9.12)     [E] (8.45)
Q32 [C] (11.69)    [B] (8.45)     [E] (7.75)

I have not used the AGC circuit as given in the original V5 but opted
for the LM324 version. However, this is not  enabled.

I have taken the Panadapter out from just before the ladder filter
(post the stage 2 TIA). This is connected to SDRSharp to check signals

For the software, I used the V1.2  with frequencies calculated based on KD8CEC:
http://www.hamskey.com/2019/02/whats-new-with-ubitx-v5-1-changed-if.html

I  used the following values:
#define SECOND_OSC_USB (56054200l)
#define SECOND_OSC_LSB (33940800l)

#define INIT_USB_FREQ (11059250l)

According to the notes in KD8CEC's blog the firstIF has been set to
45005000L due to L7 and L5 pulling the crystal filter by 5KHz

Using the PanAdapter tap point that has been provided for I can see
that the signal passes through at just about 45.000.000 MHz, but at
times (start up) the signal can be heard on SDR# on 44.993.400.


Going backwards, I have used a signal injector from the input of the
audio amp to the output of the crystal stage and have a good noise
injection level at the speaker. If I use the signal injector at the
input side of crystal filter there is no sound.

I am using a local MW station on 1458KHz as this is the only station
that I can hear via SDR# (AM). The beat seems correct.

I can hear this station on the uBITx speaker very faintly (if I put my
ear next to it).

I am unable to copy any Ham stations or WWV or any other HF broadcast stations.

On start up I can hear a slight crackling noise through the speaker,
but have no clue where this is being generated.

To ensure that the SI5351 was calibrated correctly I used :
https://groups.io/g/BITX20/wiki/Si5351-Calibration-Sketch

and saved the value in the program

I have a RF milivoltmeter (homebrew) using a AD8307 and LM358
(uncalibrated), this is showing signal levels at testpoints. I haven't
done a thorough test at all points yet.

I have injected a 20mV(approx) using a AD9851 into the antenna input I
can hear the zero beat (14.150). With a stronger signal injection the
speaker jumps around quite a bit :-)

I have the following few questions ( few)
1. How do I know that the uBITx is tuned correctly
2. The volume level through the speaker is very poor.
3. Are the voltage levels on the transistors correct?
4. Shouldn't the Pandadapter (RTL dongle + SDR#) show the spectrum of
a larger bandwidth rather than just the tuned frequency at 45MHz?
5. Are the stages amplifying correctly?
6. How do I locate the source of the crackling? This dies down in a few mins.

I have access to a DSO, what checks can I do to verify the working and
improve the sound level?

Thoughts suggestions and comments welcome.

Sorry once again for the long post and thanks for reading. Have a great weekend.

Best 73,

Ravi/M0RVI










--
I'm here to add more value to the world than I'm using up.



Ashhar Farhan
 

ravi,
which firmware version are you using? it might help to trace a signal. inject a 100mv signal and trace it with a scope on the rx path..
- f

On Sun, Jun 9, 2019 at 11:35 AM MVS Sarma <mvssarma@...> wrote:
Ravi jee, 
Just use kd8cec , select the lcd type in ubitx.h, select ver5 on main file, just compile. 

Later pwer on Nd while calibrating  change bfo to 1105550 and click ptt and save. Also power cycle.
Later select wwv and complete calibration.if needed few steps of bfo.

You should succeed. Atb
Sarma vu3 zmv



On Sat, 8 Jun 2019, 8:14 pm Ravi Miranda <ravimiranda@... wrote:
Hi All,

Apologies for the long post.

Background
I built a V5 using the circuit here:
http://www.hfsignals.com/wp-content/uploads/2019/02/ubitx_v5.pdf

I have also included the mods (BFR106) and changed the resistors as
specified. Only the RX stage has been enabled.
For the stages I used :
http://w7zoi.net/bidirectional_matched_amplifier.pdf keeping the
original values intact

The ladder crystal filter has been built with 11.0592 Mhz Crystals.

The voltages for the RX side (only) transistors are as follows:
Q10 [C] (9.33)     [B] (2.02)      [E] (1.31)
Q11 [C] (11.69)    [B] (9.33)     [E] (8.62)
Q12 [C] (11.69)    [B] (8.62)     [E] (7.89)


Q30 [C] (9.12)     [B] (2.06)      [E] (1.38)
Q31 [C] (11.69)    [B] (9.12)     [E] (8.45)
Q32 [C] (11.69)    [B] (8.45)     [E] (7.75)

I have not used the AGC circuit as given in the original V5 but opted
for the LM324 version. However, this is not  enabled.

I have taken the Panadapter out from just before the ladder filter
(post the stage 2 TIA). This is connected to SDRSharp to check signals

For the software, I used the V1.2  with frequencies calculated based on KD8CEC:
http://www.hamskey.com/2019/02/whats-new-with-ubitx-v5-1-changed-if.html

I  used the following values:
#define SECOND_OSC_USB (56054200l)
#define SECOND_OSC_LSB (33940800l)

#define INIT_USB_FREQ (11059250l)

According to the notes in KD8CEC's blog the firstIF has been set to
45005000L due to L7 and L5 pulling the crystal filter by 5KHz

Using the PanAdapter tap point that has been provided for I can see
that the signal passes through at just about 45.000.000 MHz, but at
times (start up) the signal can be heard on SDR# on 44.993.400.


Going backwards, I have used a signal injector from the input of the
audio amp to the output of the crystal stage and have a good noise
injection level at the speaker. If I use the signal injector at the
input side of crystal filter there is no sound.

I am using a local MW station on 1458KHz as this is the only station
that I can hear via SDR# (AM). The beat seems correct.

I can hear this station on the uBITx speaker very faintly (if I put my
ear next to it).

I am unable to copy any Ham stations or WWV or any other HF broadcast stations.

On start up I can hear a slight crackling noise through the speaker,
but have no clue where this is being generated.

To ensure that the SI5351 was calibrated correctly I used :
https://groups.io/g/BITX20/wiki/Si5351-Calibration-Sketch

and saved the value in the program

I have a RF milivoltmeter (homebrew) using a AD8307 and LM358
(uncalibrated), this is showing signal levels at testpoints. I haven't
done a thorough test at all points yet.

I have injected a 20mV(approx) using a AD9851 into the antenna input I
can hear the zero beat (14.150). With a stronger signal injection the
speaker jumps around quite a bit :-)

I have the following few questions ( few)
1. How do I know that the uBITx is tuned correctly
2. The volume level through the speaker is very poor.
3. Are the voltage levels on the transistors correct?
4. Shouldn't the Pandadapter (RTL dongle + SDR#) show the spectrum of
a larger bandwidth rather than just the tuned frequency at 45MHz?
5. Are the stages amplifying correctly?
6. How do I locate the source of the crackling? This dies down in a few mins.

I have access to a DSO, what checks can I do to verify the working and
improve the sound level?

Thoughts suggestions and comments welcome.

Sorry once again for the long post and thanks for reading. Have a great weekend.

Best 73,

Ravi/M0RVI










--
I'm here to add more value to the world than I'm using up.



Curt
 

Ravi

Fantastic on your homebrew scratch build. Based upon all the clues, I wonder if there may be a missing connection at the crystal filter. Either try injecting a signal before and after it. If no signal source, use a wire or antenna to grab some signals and noise at the frequency. Also you might bypass that filter with a wire. If the crystal filter is the issue, then try pressing on each crystal. A smaller chance your BFO is way off, not letting signals through hear that become low enough frequency audio.

Its likely one or two simple things. Yes even touching the input of the audio should cause some buzz.

The ubitx purposely has minimal gain to make an excellent receiver. Audio level to drive a speaker is scarce even when its working well.

Curt

Ravi Miranda
 

Hi Sarma, Farhan, Curt,

Thank you all for replying so quickly. I have carried out the following:


a. I have used KD8CEC v1.20 for uBITx V5
b. The #define has been set for V5
c. I have an approx. 100mV signal now (10MHz) and injected that. On
hearing low output at the output, I proceeded to do the math to
calculate the values at each stage.

Here are the equations used. Assuming USB

1. IF_A_FREQ = VFO FREQ - INP_FREQ [IF_A_FREQ ---- should be a value
of 45MHz so that it can get through the 45 MHz crystal filter
+/-7.5Khz]
2. OP_FREQUENCY = IF_LOCAL_OSC - IF_A_FREQ [OP_FREQUENCY ---- should
be centred on 11.0592 000 (or thereabouts) to get through the Ladder
filter
3. AUDIO_OUT = BFO_FREQUENCY - OP_FREQUENCY [If both match correctly,
we get a ZERO Beat] if the BFO_FREQUENCY > OP_FREQUENCY we get LSB and
the other way we get USB.

Using these calculations, I arrived at a frequency difference of 6660
[strange number if you get the drift :-) ] No pun intended.

With no calibration, I got nothing, not surprising as the frequency was way off.

Using a frequency meter, I set the calibration of the XTAL from
25.000.000 to 25.003.090 (This value was found using
https://groups.io/g/BITX20/wiki/Si5351-Calibration-Sketch)
The pitch of the tone may have changed, not sure at this stage it was very late.

Using the IF Shift menu option I moved the IFShift to 6660, and the
tone was clearly there. [LOUD]

Having set this right (so far), I tried the whip antenna in the
balcony (sorry no dipole). There are no signals to be heard at all. So
I have the following questions.
1. Should I change the VFO base frequency to 45.005.000 (given that
the two inductances at both sides are pulling the crystal filter off?
If so what is the best value to set this to, and where in the program
2. Are the equations above correct
3. Instead of the IFShift of 6600 should I be thinking of changing the
#define SECOND_OSC_USB (56054200l)
#define SECOND_OSC_LSB (33940800l)
to better take into account the shift and therefore bring the shift
(as shown in pt.3 above to 0)
4. To improve reception of signals with my antenna, should I add an RF
preamp prior to the antenna input? This could be switched in via a
relay and not kept in the transmit path (not really sure here as I
haven't managed to test transmit section yet.
5. What are the effects of setting lower or higher current values for
SI5351(2,4,6,8)

Is there a worked example that has
a. BASE_VFO_FREQUENCY
b. USB_FREQUENCY
c. LSB_FREQUENCY
d. BFO_FREQUENCY

I can then use the calibration program to generate these three signals
and do measurements?

Many thanks for taking time to help me with this.

Best 73,

Ravi/M0RVI


On Sun, 9 Jun 2019 at 17:31, Curt via Groups.Io
<wb8yyy=yahoo.com@groups.io> wrote:

Ravi

Fantastic on your homebrew scratch build. Based upon all the clues, I wonder if there may be a missing connection at the crystal filter. Either try injecting a signal before and after it. If no signal source, use a wire or antenna to grab some signals and noise at the frequency. Also you might bypass that filter with a wire. If the crystal filter is the issue, then try pressing on each crystal. A smaller chance your BFO is way off, not letting signals through hear that become low enough frequency audio.

Its likely one or two simple things. Yes even touching the input of the audio should cause some buzz.

The ubitx purposely has minimal gain to make an excellent receiver. Audio level to drive a speaker is scarce even when its working well.

Curt


--
I'm here to add more value to the world than I'm using up.

Sandeep Lohia
 


On Mon 10 Jun, 2019, 6:40 PM Ravi Miranda, <ravimiranda@...> wrote:
Hi Sarma, Farhan, Curt,

Thank you all for replying so quickly. I have carried out the following:


a. I have used KD8CEC v1.20 for uBITx V5
b. The #define has been set for V5
c. I have an approx. 100mV signal now (10MHz) and injected that. On
hearing low output at the output, I proceeded to do the math to
calculate the values at each stage.

Here are the equations used. Assuming USB

1. IF_A_FREQ = VFO FREQ - INP_FREQ  [IF_A_FREQ ---- should be a value
of 45MHz so that it can get through the 45 MHz crystal filter
+/-7.5Khz]
2. OP_FREQUENCY = IF_LOCAL_OSC - IF_A_FREQ [OP_FREQUENCY ---- should
be centred on 11.0592 000 (or thereabouts) to get through the Ladder
filter
3. AUDIO_OUT = BFO_FREQUENCY - OP_FREQUENCY [If both match correctly,
we get a ZERO Beat] if the BFO_FREQUENCY > OP_FREQUENCY we get LSB and
the other way we get USB.

Using these calculations, I arrived at a frequency difference of 6660
[strange number if you get the drift :-)  ] No pun intended.

With no calibration, I got nothing, not surprising as the frequency was way off.

Using a frequency meter, I set the calibration of the XTAL from
25.000.000 to 25.003.090 (This value was found using
https://groups.io/g/BITX20/wiki/Si5351-Calibration-Sketch)
The pitch of the tone may have changed, not sure at this stage it was very late.

Using the IF Shift menu option I moved the IFShift  to 6660, and the
tone was clearly there. [LOUD]

Having set this right (so far), I tried the whip antenna in the
balcony (sorry no dipole). There are no signals to be heard at all. So
I have the following questions.
1. Should I change the VFO base frequency to 45.005.000 (given that
the two inductances at both sides are pulling the crystal filter off?
If so what is the best value to set this to, and where in the program
2. Are the equations above correct
3. Instead of the IFShift of 6600 should I be thinking of changing the
#define SECOND_OSC_USB (56054200l)
#define SECOND_OSC_LSB (33940800l)
to better take into account the shift and therefore bring the shift
(as shown in pt.3 above to 0)
4. To improve reception of signals with my antenna, should I add an RF
preamp prior to the antenna input? This could be switched in via a
relay and not kept in the transmit path (not really sure here as I
haven't managed to test transmit section yet.
5. What are the effects of setting lower or higher current values for
SI5351(2,4,6,8)

Is there a worked example that has
a. BASE_VFO_FREQUENCY
b. USB_FREQUENCY
c. LSB_FREQUENCY
d. BFO_FREQUENCY

I can then use the calibration program to generate these three signals
and do measurements?

Many thanks for taking time to help me with this.

Best 73,

Ravi/M0RVI


On Sun, 9 Jun 2019 at 17:31, Curt via Groups.Io
<wb8yyy=yahoo.com@groups.io> wrote:
>
> Ravi
>
> Fantastic on your homebrew scratch build. Based upon all the clues, I wonder if there may be a missing connection at the crystal filter. Either try injecting a signal before and after it. If no signal source, use a wire or antenna to grab some signals and noise at the frequency. Also you might bypass that filter with a wire. If the crystal filter is the issue, then try pressing on each crystal. A smaller chance your BFO is way off, not letting signals through hear that become low enough frequency audio.
>
> Its likely one or two simple things. Yes even touching the input of the audio should cause some buzz.
>
> The ubitx purposely has minimal gain to make an excellent receiver. Audio level to drive a speaker is scarce even when its working well.
>
> Curt
>



--
I'm here to add more value to the world than I'm using up.



Jerry Gaffke
 

Ravi,

Your equations look correct, though this might be a more concise description of the math involved: 
    https://groups.io/g/BITX20/message/44515

That was for a uBitx-v3, so had the 12mhz IF crystals, not 11.052mhz.
Those IF crystals get sorted at hfsignals into bins by frequency such that all crystals
used in any given rig are of the same frequency within perhaps 100hz or better.
Between rigs using crystals from different sorting bins, the 12mhz (or 11.0592mhz)
crystal filter can vary from rig to rig by a khz or so.
Some have found that the rig sounds better if the BFO is moved away
from its factory value by a few hundred hz.

Likewise, the center frequency of 45mhz filter might vary by a few khz,
but it is wide enough that you probably would not notice any reduced sensitivity
or change in audio quality without a direct A/B test.

An RF preamp may be needed to hear much if operating with a short whip.

Several here have played with different si5351 output drive levels and came to
different conclusions.  This can affect signal levels and birdies, but generally isn't critical.
The ideal settings might vary a bit from rig to rig, and your local incoming RF levels. 

Posts 35235 and 54501 describe a calibration procedure that might be of interest. 

Jerry, KE7ER


On Mon, Jun 10, 2019 at 06:09 AM, Ravi Miranda wrote:
Hi Sarma, Farhan, Curt,

Thank you all for replying so quickly. I have carried out the following:


a. I have used KD8CEC v1.20 for uBITx V5
b. The #define has been set for V5
c. I have an approx. 100mV signal now (10MHz) and injected that. On
hearing low output at the output, I proceeded to do the math to
calculate the values at each stage.

Here are the equations used. Assuming USB

1. IF_A_FREQ = VFO FREQ - INP_FREQ [IF_A_FREQ ---- should be a value
of 45MHz so that it can get through the 45 MHz crystal filter
+/-7.5Khz]
2. OP_FREQUENCY = IF_LOCAL_OSC - IF_A_FREQ [OP_FREQUENCY ---- should
be centred on 11.0592 000 (or thereabouts) to get through the Ladder
filter
3. AUDIO_OUT = BFO_FREQUENCY - OP_FREQUENCY [If both match correctly,
we get a ZERO Beat] if the BFO_FREQUENCY > OP_FREQUENCY we get LSB and
the other way we get USB.

Using these calculations, I arrived at a frequency difference of 6660
[strange number if you get the drift :-) ] No pun intended.

With no calibration, I got nothing, not surprising as the frequency was way off.

Using a frequency meter, I set the calibration of the XTAL from
25.000.000 to 25.003.090 (This value was found using
https://groups.io/g/BITX20/wiki/Si5351-Calibration-Sketch)
The pitch of the tone may have changed, not sure at this stage it was very late.

Using the IF Shift menu option I moved the IFShift to 6660, and the
tone was clearly there. [LOUD]

Having set this right (so far), I tried the whip antenna in the
balcony (sorry no dipole). There are no signals to be heard at all. So
I have the following questions.
1. Should I change the VFO base frequency to 45.005.000 (given that
the two inductances at both sides are pulling the crystal filter off?
If so what is the best value to set this to, and where in the program
2. Are the equations above correct
3. Instead of the IFShift of 6600 should I be thinking of changing the
#define SECOND_OSC_USB (56054200l)
#define SECOND_OSC_LSB (33940800l)
to better take into account the shift and therefore bring the shift
(as shown in pt.3 above to 0)
4. To improve reception of signals with my antenna, should I add an RF
preamp prior to the antenna input? This could be switched in via a
relay and not kept in the transmit path (not really sure here as I
haven't managed to test transmit section yet.
5. What are the effects of setting lower or higher current values for
SI5351(2,4,6,8)

Is there a worked example that has
a. BASE_VFO_FREQUENCY
b. USB_FREQUENCY
c. LSB_FREQUENCY
d. BFO_FREQUENCY

I can then use the calibration program to generate these three signals
and do measurements?

Many thanks for taking time to help me with this.

Best 73,

Ravi/M0RVI

Ravi Miranda
 

Jerry/KE7ER

Many thanks for your help. Will have a look and report back.

Best 73,

Ravi/M0RVI

On Mon, 10 Jun 2019 at 16:51, Jerry Gaffke via Groups.Io
<jgaffke=yahoo.com@groups.io> wrote:

Ravi,

Your equations look correct, though this might be a more concise description of the math involved:
https://groups.io/g/BITX20/message/44515

That was for a uBitx-v3, so had the 12mhz IF crystals, not 11.052mhz.
Those IF crystals get sorted at hfsignals into bins by frequency such that all crystals
used in any given rig are of the same frequency within perhaps 100hz or better.
Between rigs using crystals from different sorting bins, the 12mhz (or 11.0592mhz)
crystal filter can vary from rig to rig by a khz or so.
Some have found that the rig sounds better if the BFO is moved away
from its factory value by a few hundred hz.

Likewise, the center frequency of 45mhz filter might vary by a few khz,
but it is wide enough that you probably would not notice any reduced sensitivity
or change in audio quality without a direct A/B test.

An RF preamp may be needed to hear much if operating with a short whip.

Several here have played with different si5351 output drive levels and came to
different conclusions. This can affect signal levels and birdies, but generally isn't critical.
The ideal settings might vary a bit from rig to rig, and your local incoming RF levels.

Posts 35235 and 54501 describe a calibration procedure that might be of interest.

Jerry, KE7ER


On Mon, Jun 10, 2019 at 06:09 AM, Ravi Miranda wrote:

Hi Sarma, Farhan, Curt,

Thank you all for replying so quickly. I have carried out the following:


a. I have used KD8CEC v1.20 for uBITx V5
b. The #define has been set for V5
c. I have an approx. 100mV signal now (10MHz) and injected that. On
hearing low output at the output, I proceeded to do the math to
calculate the values at each stage.

Here are the equations used. Assuming USB

1. IF_A_FREQ = VFO FREQ - INP_FREQ [IF_A_FREQ ---- should be a value
of 45MHz so that it can get through the 45 MHz crystal filter
+/-7.5Khz]
2. OP_FREQUENCY = IF_LOCAL_OSC - IF_A_FREQ [OP_FREQUENCY ---- should
be centred on 11.0592 000 (or thereabouts) to get through the Ladder
filter
3. AUDIO_OUT = BFO_FREQUENCY - OP_FREQUENCY [If both match correctly,
we get a ZERO Beat] if the BFO_FREQUENCY > OP_FREQUENCY we get LSB and
the other way we get USB.

Using these calculations, I arrived at a frequency difference of 6660
[strange number if you get the drift :-) ] No pun intended.

With no calibration, I got nothing, not surprising as the frequency was way off.

Using a frequency meter, I set the calibration of the XTAL from
25.000.000 to 25.003.090 (This value was found using
https://groups.io/g/BITX20/wiki/Si5351-Calibration-Sketch)
The pitch of the tone may have changed, not sure at this stage it was very late.

Using the IF Shift menu option I moved the IFShift to 6660, and the
tone was clearly there. [LOUD]

Having set this right (so far), I tried the whip antenna in the
balcony (sorry no dipole). There are no signals to be heard at all. So
I have the following questions.
1. Should I change the VFO base frequency to 45.005.000 (given that
the two inductances at both sides are pulling the crystal filter off?
If so what is the best value to set this to, and where in the program
2. Are the equations above correct
3. Instead of the IFShift of 6600 should I be thinking of changing the
#define SECOND_OSC_USB (56054200l)
#define SECOND_OSC_LSB (33940800l)
to better take into account the shift and therefore bring the shift
(as shown in pt.3 above to 0)
4. To improve reception of signals with my antenna, should I add an RF
preamp prior to the antenna input? This could be switched in via a
relay and not kept in the transmit path (not really sure here as I
haven't managed to test transmit section yet.
5. What are the effects of setting lower or higher current values for
SI5351(2,4,6,8)

Is there a worked example that has
a. BASE_VFO_FREQUENCY
b. USB_FREQUENCY
c. LSB_FREQUENCY
d. BFO_FREQUENCY

I can then use the calibration program to generate these three signals
and do measurements?

Many thanks for taking time to help me with this.

Best 73,

Ravi/M0RVI



--
I'm here to add more value to the world than I'm using up.