Just confirmed that it will build if you stash the changes to that file (not sure why it ships with uncommitted changes? Haven't seen that documented anywhere). Also, I had the wrong link to the front panel file:



Unfortunately, after installing the messenger branch of the zbitx repository and front panel, I'm still not seeing the messenger option, so I think the version he showed in the video isn't yet available. The software is also a bit behind in other fixes, so probably worth waiting on this one.

-Grant



On Sun, May 25, 2025 at 11:34?AM Grant Brown via groups.io <> <grant.brown73@...> wrote:

Still haven't had a chance to dig into the software, so I'm not
sure if this is expected by default or a change on your end, but
the error is just that there are local changes to a file that
haven't been added to the git repository. The fix is likely
simple, though you do run the risk of tying yourself in git knots.
Probably worth a trip to YouTube university (or making sure to
have a backup).

If you want to soldier ahead, two methods would be:

1. Revert any changes and try again.

Running "git stash" will restore that file to it's canonical state
in the repository. You can return your changes by running "git
stash apply"

2. Save the changes

To add the changes to the repo, there are two steps. After
navigating to the root directory of the repo, you can "stage" all
changes to files already present by running:

"git add -u ./"

Then, you can commit:

git commit -m "my changes"

Then you can try updating again. If git can't figure out how to
merge the changes, it will put both versions in the file in
question and ask you to edit them manually (pain).

In the meantime, one really nice tool for looking at the current
state of the repository is gitk, which can be installed via apt.
Just install and run while in the repository: "gitk", and it will
pop up a GUI with changes. Then you can see what's up with that
file (I'm assuming it's a file and not something more complicated
like a submodule).

Will try to fire this up later today or tomorrow to see for myself.

-Grant

Sent from my phone

On Sun, May 25, 2025, 9:55?AM Vince d'Eon VE6LK/AI7LK via
groups.io <> <vincedeon@...> wrote:

Unfortunately this approach throws errors, see screengrab
I'm sure this is something simple, however it is beyond me as
I don't do github at all.

Some further experiments, pictures, and thoughts:

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For these experiments, the Q3 transmit IF Buffer amplifier stage, and the Q4 receive IF buffer stage have been completely removed from the picture with the removal of C46, C49, and C51. I am feeding a 40 MHz signal from an HP signal generator directly into the D3/D4 diode ring mixer transformer T1. This eliminates the possibility of RF pickup and distortion caused by Q3 or Q4. The SI5351 in the ZBitx provides the Local Oscillator signal in all cases. I have adjusted the output of the signal generator to get about 4 Watts of RF output from the transmitter:

This is pretty close to what I was seeing with my modified Q3 stage driving the mixer.

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I then connected the spectrum analyzer to the output of the D3/D4 mixer lowpass filter network at L21. I removed C212 which is a tap for the receiver circuitry, to remove that variable. The spectrum analyzer does place an additional load at the lowpass filter output, which reduces transmit RF power output slightly.

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This shows the output of the lowpass filter while in receive:

Two interesting things of note: the 2 MHz spur is about 60 dB down. There's a 12 MHz spur about 54 dB down. Again, the transmitter is not transmitting.

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This shows the output of the lowpass filter while transmitting 4 Watts:

The 12 MHz spur is now about 45 dB down. A spur is visible at 2 MHz, also about 45 dB down. The increase in level of these spurs cannot be caused by any circuitry around the transmit IF amplifier Q3, or the receive IF amplifier Q4, since they are both completely out of the circuit. RF energy is getting into the D3/D4 mixer from the transmitter via some other path(s) that are currently not known.

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Here's what the output of the transmitter looks like - again about 4 Watts. I put a 50 Ohm termination at the output of the D3/D4 mixer lowpass filter where the spectrum analyzer was connected, to load the circuit in a similar manner as the spectrum analyzer did:

The 12 MHz spur is about the same amplitude relative to the 14 MHz carrier. However the 2 MHz spur has grown significantly. This could be caused by higher gain in the TX chain at lower frequencies. I have not measured the gain vs frequency of the ZBitx transmit chain, however.

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Next I connected the spectrum analyzer directly to the RF port of the D3/D4 mixer stage, before the mixer lowpass filter network. The lowpass filter was completely removed from the circuit by removing C80 and L16, so the mixer only saw the spectrum analyzer for a termination, which should be close to 50 Ohms. No RF was getting to the transmit chain, so there was no RF output from the transmitter. Here's the sweep from 0 - 100 MHz:

Four significant output components are seen - 14 MHz, 40 MHz, 54 MHz, and 94 MHz.

The mixing of the 40 MHz IF input and the 54 MHz signal from the SI5351 produces the two results of 54 - 40 = 14 MHz, and 54 + 40 = 94 MHz.

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Here's the sweep from 0 - 25 MHz:

This is a pretty good result. Spurs are 60+ dB down from the 14 MHz carrier. Note that this sweep actually looks better than what's coming out of the mixer lowpass filter! This picture also shows that the SI5351 is capable of doing a pretty good job.?

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My next steps:

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1) Look again at providing a wideband termination for the RF port of the mixer. As shown above, there's RF energy at 40 MHz, 54 MHz, and 94 MHz coming out of the RF port of the mixer. The lowpass filter only passes RF below approximately 30 MHz, so it reflects energy above 30 MHz. The 40, 50, and 94 MHz components are being reflected back into the mixer where they can cause problems. Diode ring mixers like to see a 50 Ohm termination at all the frequencies that appear at their ports. M0NTV has several great Youtube videos about mixers that explain how they work and how proper termination can make a big difference.

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2) Sweep the transmit chain to determine gain vs frequency. If it's significantly higher in gain at low frequencies, then some hardware adjustments can be made to better equalize the gain, with the effect of reducing the 2 MHz spur. The software gain compensation settings would have to be readjusted to work with the revised transmitter gain vs frequency curve.

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3) Continue investigating how transmit RF energy is leaking into the mixer.

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73; Steve, N3SB

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On May 26, 2025, at 00:55, Steve Beckman via groups.io <ssteven3sb@...> wrote:

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Hi Ron;

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C22 is not too hard to get at. First find the 7805 voltage regulator, which is attached to the heat sink. Q3 is close to the 7805 and the crystal filter network. Once you identify the emitter of Q3, you will be able to trace to copper tracks to C22 and R29.

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<C22_picture.jpg>

R29 is the resistor marked 470. C22 is to the right of R29. R33 is to the right of C22.

R33 is the most clearly identified. The identifiers for R29 and C22 are obscured by other markings.

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I have found it helpful to apply some tin/lead solder to the joints of the SMT parts before attempting to remove them. It could be that the PCB was build with lead-free solder, which has a higher melting point. The addition of the tin/lead solder lowers the melting temperature and makes the SMT part easier to remove.

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I've found the SMT resistor, capacitor, and inductor assortments available on Amazon to be very handy for experimenting.

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73; Steve, N3SB

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