X6100 on John Flinchbaugh KD3EE

X6100 R1CBU 0.32.2

Tue, 27 Jan 2026 00:00:00 +0000

Upgrade

I upgraded to R1CBU 0.32.2. It tested fine with WSJT-X.

It has a new IF-shift feature to move birdies in the menu, but it was “unavailable” on the old base firmware I was running, so I had to upgrade to Base 1.1.9:

https://www.radioddity.com/pages/xiegu-download
write the image to an SD card
boot it
let it restart
apply the base 1.1.9 upgrade from the system / firmware menu on the stock firmware

Upgrading the base to 1.1.9 went OK after figuring out some issues with a bad /dev/sdb device handle on my Linux notebook.

New Features

Now I can “IF Shift” when I find a birdie near or in the passband I’m trying to hear. It binds nicely to the bottom MFK for quick access.

This firmware continues to work for FT8. I tested power output with CW as well, since there was a note about needing to applying an output gain.

It’s nice to see the discrete values from the graphs also on the screen: received signal, TX power, SWR.

I’ve been experimenting for a while with 2 stop bits in flrig to get the initial connection to succeed more often. Sometimes it helps, and sometimes it doesn’t. I was hoping this update may help, but there’s no difference. I’ll go back to 1 stop bit.

R1CBU 0.31.2

Mon, 11 Aug 2025 00:00:00 +0000

R1CBU 0.31.2 has been out for a while, so I finally upgraded. The only fix didn’t matter to me so much, but it was time to get up-to-date.

US-4361 King's Gap

Sun, 25 May 2025 00:00:00 +0000

The activation at King’s Gap Environmental Education Center, US-4361 was tough-going, even though I was at the top of the mountain. I used the GRA vertical whip with tapped coil. Internet access flaked early, so successfully spotted myself on APRS with APSPOT.

Setup

Antenna

APRS Spot

R1CBU 0.30.0 Firmware Update

Mon, 12 May 2025 00:00:00 +0000

Changes

R1CBU 0.30.0 brings several notable changes:

The ATT/PRE indicator has been split again, allowing them to operate independently.
A fix for storing/loading of the ATU network has been implemented. This is a different implementation from the PR I submitted.
Controls for an alternate patched baseband have been added, though I haven’t tried the new baseband yet.

Testing

The software continues to reload preferences from the previous version, which is good. The UI changes look promising. However, the Maximum Usable Frequency (MUF) has been low for the past couple of weeks, making 20M barely usable today. Despite that challenge, I can still see my reports on PSKReporter on 20M. I’ve been keeping my power at around 2W for the past couple of months. My first contact with this new firmware was hunting a park near Memphis, TN, on FT8, using 2W.

X6100 R1CBU 0.29.2 ATU Bug

Tue, 08 Apr 2025 00:00:00 +0000

I encountered a bug with the ATU in the X6100 running R1CBU firmware version 0.29.2.

The ATU networking information is stored in both a cache and the params.db file. When setting multiple tunings close to each other (e.g., 7073, 7074, 7075 kHz), the radio would rapidly cycle through them as the VFO was spun. This behavior cluttered the configurations and made it difficult for the ATU network to hold a stable tune near a signal.

Upon investigation, I discovered that while the cache retained all these closely spaced tunings, the params.db only saved one of them. The intention behind the new feature in R1CBU was to remove the hard boundaries between ATU configurations (which were previously every 25 or 50 kHz), allowing a single tuning network to be effective within approximately 25 kHz in either direction. The database would correctly update a nearby frequency to the middle, but the cache’s retention of every tuning caused the “thrashing” effect. Switching antennas or cycling power would reload the sparser collection of networks from the database, temporarily resolving the issue.

I filed a bug report, and submitted a pull request to fix it.

I patched the ATU code to reload the cache from the database immediately, effectively discarding the extraneous nearby networks.

ATU Bug in R1CBU 2.29.2

Thu, 13 Mar 2025 00:00:00 +0000

I encountered a bug using the ATU on R1CBU 0.29.2. I had lots of tunings very near each other, so it switched a lot. It queries and uses the nearest tuning to current frequency, so lots of close tunings will cause thrashing as you move. I cleared the atu table in params.db to alleviate the problem for a bit.

POTA US-1356 Gifford Pinchot

Sat, 22 Feb 2025 00:00:00 +0000

I visited Gifford Pinchot State Part, US-1356, and strung up the EFHW from a picnic table to a tree. I managed it in 1 throw to a nice spot. I made 20 contacts:

18 FT8
2 CW, including N4T, the Dry Tortugas DXpedition

Using R1CBU 0.29.1, I knew to pay special attention to undo the AM bug from SWR Scan by switching through modes after an SWR Scan. In this firmware, though, WSJTX would set digital mode (USB-D) and it would bounce back to USB, which doesn’t take sound from the connection to the computer. I had to work around it by disabling WSJTX’s ability to set the mode. Then I could set USB-D and it would stay there.

entire setup

R1CBU 0.29.2

Sat, 22 Feb 2025 00:00:00 +0000

After my park outing, I returned to find an update to R1CBU 0.29.2. It includes fixes for:

SWR Scan that leaves the radio in AM mode
CAT control of modes

X6100 Crashing

Wed, 12 Feb 2025 00:00:00 +0000

My X6100 started freezing up its user-interface. This happens sometimes when the radio board shuts off, but the UI board hasn’t yet. It would happen when I was transmitting, even very low power, 2W. It even did it after a long time just listening.

I unplugging the USB-C from the computer, and it would allow the UI to shutdown, so the USB-C was powering the UI board, while the radio board had shutdown. The internal battery indicator looked like it may have shown low for a moment, but I was on 12V.

I finally realized I had enabled battery charging all the time. Charging the mostly-worn-out battery caused this new shutdown problem. I disabled charging, and now the radio is running fine again.

I ordered 2 new internal battery packs from Amazon to install. I used to be able to run the radio on internal battery for a little while, but now as soon as I unplug external power, the battery will read something terribly low like 7% and about 6 volts.

X6100 Firmware Again

Mon, 23 Sep 2024 00:00:00 +0000

Xiegu released another updated firmware for the X6100: APP 1.1.9 & BASE 1.1.8, dated 2024-09-23.

I downloaded it from Radioddity, and wrote it to an SD card:

$ sudo dd if=sdcard.img of=/dev/sda bs=1M status=progress

I booted the new card for the app upgrade to 1.1.9,
I applied baseband 1.1.8 from the menu in the UI.
I tried the CW key in the stock firmware, and it transmitted (unlike last time).
I booted back to R1CBU, and it looked good there as well.

I did a little FT8, decoded some CW, and listened to some SSB on 40m. I found I could to turn the RF Gain closer to 100 instead of below 63. It may be reading slightly lower power on the display before ALC kicks in: up to but not over the 5W, where it used to often push a little past.

It’ll stay.

Failed Upgrade for X6100

Fri, 06 Sep 2024 00:00:00 +0000

Radioddity had the new firmware for the X6100. I downloaded it, wrote it, installed it, and rebooted it to see the stock APP 1.1.8 and BASE 1.1.7. That mostly-useless audio spectrum is gone. The strange jump at 63 in RF GAIN is fixed.

BUT transmitting gave NO POWER. R1CBU also exhibited the problem. When I downgraded to BASE 1.1.6, it transmitted again. Others had seen this problem as well, while others had it work. It must have depended upon variations in the hardware.

New Firmware for X6100

Fri, 07 Jun 2024 23:44:38 -0400

There’s a new person building onto Oleg’s R1CBU firmware. He first made a patch TGZ available, and then an entire image.

He has a repo for this work, and it includes some build instructions which reference the buildroot and submodules. I think I’m close to being able to build it, but I’m seeing some errors trying to find the xkbcommon headers.

I did patch his source with my DB changes. I built the DB: sqlite3 params.db < params.sql, mounted the DATA partition, and copied my custom params.db to it.

It’s looking nice so far. I can use flrig and have wsjtx and fldigi both talk to it simultaneously. That’s the main improvement in my mind, but it includes some other fixes:

volume encoder can be spun quickly now
smoothing of the TX/SWR graphs
finer detail in the waterfall

EFHW Test 2

Sun, 19 May 2024 00:00:00 +0000

I ran out to Susquehanna Riverlands State Park (US-9719) to test the EFHW again. This time I tied it to a bush and a picnic table and raised the center with the fishing pole mast.

I took the time to sweep all the bands with the X6100’s built-in analyzer app. 40m looked like it could stand to have the wire slightly shorter, but when I transmitted, the SWR looked fine. I saw about 1.5:1 SWR on 40, 20, and 15. 10 was a little off, so I guess I’ll add the 100pf capacitor that most people use.

The tuner made 12m and 17m work, so I made FT8 contacts on 40m, 20m, 15m, and 17m.

I was also trying out some of the combo winder/unun I 3d printed and made some notes. I’ll post my remix soon of another person’s OpenSCAD code. I like the all-in-one designs that wrap up into one package, but I wonder how much that will hinder my random experimentation with antennas.

While transmitting, I noticed the Evolve 3 laptop’s mouse would stop responding. I had seen this on other laptops using the 1/4 wave HF vertical. I added the common mode choke to the feed line near the radio, and that cleared up. There was already a choke near the antenna, but I guess it wasn’t enough. I love when I can see a clear cause and effect or problem and solution.

Riverlands Sign

Riverlands Rain

Riverlands Operating

Revisiting Power Noise

Thu, 18 Apr 2024 16:59:56 -0400

When I first started with the X6100, I’d see some noise that buried real signals when plugged into AC power.

Running on battery was fine, and running on the external lead-acid 12V battery was OK too. For weeks, I used the battery to smooth the noise. I’d run an AC power supply in parallel with the battery and turn it up just high enough that I didn’t see noise in the waterfall. The battery smoothed the power.

I switched to a LiFePO4 battery, and I found the built-in charging circuit made it hard to balance input power and output power just right to keep it smooth.

I asked around on the X6100 mailing list and I got 2 suggestions I took:

a filter I can use with any cheap power supply I already have
a cleaner, and inexpensive, switching power supply from Ateck that puts out a fixed 12V/5A (Part#: PS120V5-D)

I purchased both to try, and both helped immensely, each on their own.

I wired up the filter with some 5525 connectors and printed a case for it. I use the filter in combination with my adjustable 24V/5A power supply on the go. That higher-voltage power supply is also useful to charge the LiFePO4 battery at 14.1V. The battery also lives in my box for portable operation.

I use the Ateck power supply on my desk by itself to power the radio at home.

Adjusting Bands on R1CBU

Sat, 23 Mar 2024 00:00:00 +0000

I updated the bands on my X6100 running R1CBU to follow the US band plan/privileges:

Clone source: https://github.com/strijar/x6100_gui
Update sql/bands_ham.csv to break bands by plan and privileges for US
Update sql/params.sql to not import band_params.csv, but to instead build it from the bands table
Rebuild the db: sqlite3 params.db < params.sql
Copy the new params.db to the DATA partition of the SD card

Rebuilding the database loses all your settings on the radio, so you have to put those back, but I can now see where the general privileges start and end on each band.

R1CBU 0.20.1

Wed, 20 Mar 2024 00:00:00 +0000

I updated my X6100 to R1CBU 0.20.1. Oleg provided a tgz with only the updated files, so I dropped the file into /DATA partition, started up the radio, and it unpacked the update. The tgz contained the x6100_ui binary and params.db.

This can be an interesting way to make my own updates without needing to know how to rebuild the entire image. I see the changes applied to his x6100_gui github repo, so I know that’s a good base for making future changes.

Learning to do make updates is interesting, because the original maintainer, Oleg, is likely done updating this firmware in favor of building his own radio in the image of the X6100. He’s frustrated trying to get help and documentation from Xiegu. I run the R1CBU firmware full-time.

R1CBU 0.20.0

Thu, 29 Feb 2024 00:00:00 +0000

A new R1CBU firmware is available for the X6100.

I wrote the image to the micro SD card:

$ sudo dd if=x6100_r1cbu_v0.20.0_sdcard.img bs=1M of=/dev/sdb status=progress

It’s working fine. Auto levels for waterfall and spectrum seems useful, but it still shows the min/max level settings that do nothing while in auto. I had to set up all preferences again, since it comes with a new database on the image.

R1CBU on X6100

Sun, 31 Dec 2023 00:00:00 +0000

I’ve loaded the R1CBU UI on the X6100. Reading the manual exposes all sorts of great features and conveniences:

Highlights

Large waterfall
Lots of options on MFK and VOL knobs, and it’s customizable
SWR scan is very fast
CW decoder is robust
ALC starts at 0.0
Serial console access: minicom -D /dev/ttyACM0, root, 123

Bugs

Setting time down to the second is weird. I used serial console and CLI instead.

ALC

Tue, 28 Nov 2023 00:00:00 +0000

Here’s a good demo of what ALC is doing. It’s clipping off the top of the signal, so turn the power up to just before ALC reacts, whether it’s 0->100 like the radio in the video or 100->0 like Xiegu radios.

Navtex

Mon, 27 Nov 2023 00:00:00 +0000

Tuned to 8416khz, I received a Navtex weather report. I tuned the X6100, CW, FIL2 set to be really narrow, and I let fldigi decode the transmission as Navtex.

Flrig

Fri, 03 Nov 2023 00:00:00 +0000

I originally had wsjt-x and js8call talking directly to X6100 to do CAT, but fldigi wants flrig, so I set it up. Now i have flrig running all the time, and have wsjt-x talk to that. Maybe it’ll be more reliable with fewer hiccups and disconnects.

X6100 Internal Battery

Fri, 03 Nov 2023 00:00:00 +0000

I’m running FT8 on 10m with only the internal battery. I’m finding I’m only able to push ~3W. SWR looks good.

On external power supply, I can push up to 10W

First HF Radio

Wed, 25 Oct 2023 00:00:00 +0000

(After passing the test, I immediately ordered a Quansheng UV-K5 HT. I also ordered this weird $120 HF radio based off the open source usdx project. The HF radio was garbage: the screen was tiny, the audio/CAT control was confusing or non-existent, and it liked to lock up and stop updating its screen. I returned it to Amazon.)

I had been in a hurry, since I was heading to Florida for the week. While I was down there, I discovered the Ham Radio Outlet in Orlando, so I ran there to look around and purchased the Xiegu X6100 QRP rig.

I also picked up a couple accessories shortly afterward to go with it:

connectors between bnc and sma
5W adjustable power supply that didn’t quite cut it all the time (24Vx5W)
10w adjustable power supply (12Vx10W)
speaker wire
banana clip connectors
Ham Radio Today: X6100 book on kindle