开云体育

Working on learning satellites for a few months now, building most of the gear, instead of buying stuff. TODAY for the first time, I heard my own CW by way of the satellite, monitoring an sBitx (V2) using a Ukranian transverter (neither of which seems to be terribly sensitive). JO-97, in its pass over the eastern USA around 11AM Eastern time. Main rig was older ICOM820H transmitting on 70cm through a homebrew yagi/homebrew dual axis rotator system controlled by homebrew PCB using K3NG controller, controlled by SAT32PC. With some effort I found my signal on THAT setup with a CAT correction of 5kHz (I don't know why that is so far off yet) SBITX SECOND RIG was a sBitx crudely "tee'd" in with simple PL259-Tee, so it got the same signal as the Icom820H. I was unable to provide suitable doppler correction to the sBitx, because Sat32PC doesn't seem to know how to use hamlib; however, I could have done so using Gpredict directly to the radio (which was on 192.168.1.10 in this experiment; the antenna rotator is controlled over wifi using a raspberry pi) The spectrum display on the sBitx was a HUGE help. I could easily see my own CW on the waterfall and therefore tune to my frequency! I would say as a first cut that the sBitx and the 820H were running reasonably about the same as far as receiving. These passes are ONLY 10 minutes long, but on he Sbitx I could SEE other SSB conversations going on (and they seemed to have more power than my signal.....) -- so I could QUICKLY tune to them on the Sbitx and receive them just fine! On the Icom820H (without a spectral display) you have to tune up and down the band. Signal Levels: I have the antenna system 50 feet out into the driveway. The 70cm transmitter is going through 100 feet of LMR400 to a crossed Yagi homebrew. The 2meter downlink goes first into a diplexer to protect it from 70cm pickup (https://www.dxengineering.com/parts/cma-cf-416a) and then into an inexpensive GaAs FET preamp Moonraker M-100 Professional (https://www.dxengineering.com/parts/mkr-20-001) turned all the way up, theoretically 20dB gain. At that level, both the 820H and the sBitx/transverter hear considerably more SIGNAL as evidenced by increased background noise. Without the preamp I'm pretty sure the Ukranian transverter and sBitx would hear nothing, and I'm not sure about the 820H -- haven't gotten good records on that. My experience with the used Icom 820H is that I generally do best by keeping that preamp at +20dB. WITH the preamp I have heard amazingly good SSB signals -- like full quieting FM quality! The sBitx was showing MY cw maybe 10-15 dB above the noise baseline (IF was set to 84 on the 10 meter band) but my recollection is that the SSB signals were 20-30 dB above noise -- stronger than my CW signal. (So maybe I need more oomph on transmit???) This proves that you can use an sBitx as a satellite downlink receiver with transverter and preamp. In fact, it would be a very nice one because of the spectral display!! I think it would be easiest to use a second sBitx or other transmitter to do the transmit side, with a second transverter, and possibly an amplifier to get some more power.....I was surprised that my signals looked weak compared to what I heard from SSB stations on the satellite. Photos below Gordon KX4Z

A buddy reported to me that my zBitx was showing 1.8s of DT in his WSJT-X console, and I can verify same with my own copy locally. I have verified that the clock on the zBitx is to the instant correct with WWV, ie. when I hear start of the tone at the top of the minute, the minute switches over on my zBitx, as well as with my NTP synchronized devices around the shack. Yet, when I answer a call or start a CQ, I'm showing as 1.8 seconds out of sync with most other people. Also what 'app' or library or whatever is being used for FT8? 73, .Vince

I am getting this band noise. It has not always been present. Could this be caused by the INA260 voltage/current sensor module I recently added? I’m asking to see if I need to remove it from my radio. I am hoping this has been discovered and fixed by someone else already. Has anyone else seen this yet? Thanks for your help in advance, David WK4DS

Just got my zBitx today. Powered up, and the nice screen pops right up. It says "Waiting for the zBitx to start..." and no other response. Been waiting a long time, but no joy. Tried power down and restart - same result. Any advice would be appreciated. 73 Dave, VE3WI

Hi, There have been few reports on this list of customers' zBITX units arriving with issues. Mine arrived in fine condition here in Australia via DHL courier. Standard packaging seems ok, with little chance for damage if treated properly. If we were to assume nothing being equal, we might be able to trace the issue starting from final "Test Report" before shipping to testing after unboxing. When I received my unit, I placed a couple of batteries in the holder, attached a dummy load, and tested it briefly using another transceiver. All seemed OK. I do not know how useful it would be, but I am attaching a photo of my test report below in case that helps. I am wondering if those that have issues with their units want to do the same in case it might help discern a pattern. I am basically a software guy, and am looking forward to buying another unit to test them together with each other, Best regards, -Rob, VK4SSE

Hi Ashhar, From another post: "I am preparing a new messagijg system that works over ft8 protocol that is different from js8call. It is more like a messenger. It needs the radio to be on, 24x7 (and why not!). That will happen ay the FDIM." Any updates? 73 Wei AG6AQ

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