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I wonder if HF Signals is still working on improving the Zbitx software, or if they’ve stopped development. It’s been weeks without any updates or news. Anybody out there wis more insight? 73 Pete

Newer expensive satellite radios have a built in spectral display that makes it really easy to find your own signal on a linear satellite's bandpass. Older satellite radios (like my icom 820H and the 910 also, I believe) do not have a spectral display and thus you have to "hunt" for your signal, which is awkward, timeconsuming and might bother others. As I understand it, you often change your TRANSMIT frequency (uplink) to match your receiver. So you are slewing your transmitter across the satellite bandpass. There are a LOT of "moving parts" to operating on satellites, so some of this may make less or more sense to some of the readers with different experiences -- my experience is only of a few months.... Getting the sBitx Spectral Display Into The Picture I discovered that I could simply "T" in the receive input of my transverter with the input of my satellite receiver -- because of the high power output of the receiver preamp able to drive both of them. That allows the transverter/sBitx (or for that matter, an Icom 7300) to DISPLAY the received spectrum, as much as 50kHz of it! It is much easier to figure out from the display where your transmitted frequency is! You can then move transmitter or receiver once you can SEE the offset. When your primary ICOM is busy receiving and transmitting, the satellite Doppler shift is constantly changing. That is being sent to your primary radio over an open-collector bidirectional TTL-level voltage from a USB dongle. I cut into that wiring, and parallel-connected a cheap UART to allow the raspberry pi in the sBix to read the commands being sent out. The software I wrote constantly receives all the receiver frequency corrections due to Doppler (ignoring the transmitter corrections) and is constantly updating the frequency of the sBitx -- so you remain tracking with your primary satellite receiver as you work on finding the offset to your transmitter. You don't have to worry about the doppler shift. You just FIND your transmitter, and seeing yourself on the sBitx makes this a ton easier. Typically once you see where to roughly go, you will then make adjustments on your primary radio until you hear yourself in that radio. then you store this new offset in your satellite software (e.g. SATPC32, which makes this pretty straightforward) -- and the next time you hope to hear/see yourself immediately. Synchronizing the sBitx/Transverter to your primary Receiver Typically there isn't a huge error here, but it is unlikely to be zero. You can fix this either BEF?ORE or AFTER working to find your transmitter. It can be easier to get this squared away first. To correct THAT offset, I added in an ability to type in + or - (followed by "enter") -- and each such entry raises or lowers the calculating driving the sBitx -- so you get your two receivers aligned as well. You could do this easily by just using both receivers on ANY signal and making the adjustment. Called "correction" the program tells you that number and the next time you get to ENTER that as a signed number of Hz when the program starts. The software I wrote is pretty old-school terminal-window command line software. I don't have my 820H with me and that makes it more difficult to fully test -- but I think I have major errors already fixed. I'll give it another day or so and then post the software source and compiled code here. I think this will help those of use working for lower-cost solutions and using older radios have a ton of fun on the linear satellites! It was SO EASY to hit the electronic keyer to send a series of DOTS and simply look for it on the waterfall of the sBitx!! I didn't have this software right then, so I wasn't able to fully capitalize on the advantage -- but I did get my radios synchronized and had a station answer my CQ leading to a nice QSO!! My FIRST over a satellite. 73 Gordon KX4Z

To find the root cause of the spurs, I worked in 2 steps: 1. I took the front panel board out of the case and connected it with jumper wires to the main board. My objective was to eliminate possible EMI from the Pi Pico into the RF board. This did not make a difference for the spurs, as they just went down by 0.5dB which is the resolution of the TinySA. 2. In the si5351v2.c code I changed 8MA to 2MA. This results in approximately 5dBm less output power (33.5 vs 38.1dBm) but also a relative reduction of the spurs by approximately 7.5dB from -28.1dBc to -35.6dBc: Reduced output power is most probably due to the fact that the zBitx uses a diode ring mixer instead of the KISS-Mixer used in the sBitx and the oscillator power to the ring mixer is provided directly by the SI5351 CLK2 output (in reality an MS5351). Also, the IF diode ring mixer gets its oscillator signal directly from the SI5351 CLK1, whereas in the sBitx there is a buffer amplifier with two 2N3904. It could be that the much higher load on the SI5351 outputs, results in some intermodulation in the SI5351, which finally shows up as spurs. Given that these spurs are a showstopper, to transmit with the zBitx as the spurs are not at least 40dB suppressed, I am looking forward to further investigation and direction by hfsignals. On Mon, Apr 14, 2025 at 11:39 PM, Ron, N6YWU wrote: -- 73, Joerg - DB2OO

My UBITX v6 was consuming 390mA in RX mode with 13.8V supply and the 5V regulator on the Raduino board was running very hot. I had a look at this schematic: http://www.lcdwiki.com/res/MSP2807/MSP2807-2.8-SPI.pdf and compared it to my display. I noticed that my 3.3V regulator U1 was bypassed with a solder blob on J1 which made me suspect that this display was actually configured for 3.3V supply voltage while it was running on the 5V it gets from the Raduino board! The resistor R5 (10 ohms in schematic, 8.2 ohms actual value in my display) suggests that the backlighter is indeed intended for 3.3V operation (the VCC3.3 net). With the existing 5V supply, I measured 225mA current through the backlighter which is much more than the recommended 60mA! This problem was solved by removing transistor Q1 and putting 33 ohms in series with R5 to ground. The backlighter current dropped to 55mA and the power dissipation in the Raduino 5V regulator dropped by 1.5W. Now it runs much cooler. Total radio consumption in RX mode dropped 170mA, from 390 to 220mA. I'm still a little worried about the LCD driver chip... As it is specified for max 3.3.V supply, I wonder how long it will survive on 5V? 73 Johan SM6LKM

Hallo! After updating the zBitx software and firmware, the zBitx no longer starts properly. Repeating the update does not work.. What can I do to get the zBitx working? vy73 Frank