Getting On The Air

Making the zBitx field-worthy

#zbitx #qrp #mods #homebrew #field-ops

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Figure 1: Labour day well spent with modifications to the zBitx and powering it using a USB-C PD trigger

Figure 1: Labour day well spent with modifications to the zBitx and powering it using a USB-C PD trigger

This promises to be yet another long post, so please bear with me1! And as always, the TLDR; version:

-Modifications I would like to make

  • A video with the changed body
  • A video of powering the zBitx from the power bank

For those who cannot wait, here is the video on Peertube:

Challenges

This is a quirky little QRP device that I’ve used in my first POTA attempt at IN-0067. If you’ve read that post, you would have noticed a few challenges I mentioned with the zBitx. There was an announcement recently about a zBitx v22, that got me out of my slumber to try and get my zBitx in better shape for my next trip3. In addition, VU3NPI posted his USB-C PD triggered approached to powering the QMX with a power bank. Given, the Labour Day weekend in VU land, I decided it was time to dust the zBitx and make some modifications to it. Before, we begin, please do read the issues I had with the zBitx.

Heat, heat and heat!

The radio heats up! If you operate on FT8, you will definitely not need any room heater. The radio becomes warm to touch even on CW and SSB. It is strange that such a low-powered device does this, but the reason’s for this is well documented4, 5, 6.

Voltage drops

One of the biggest challenges I had when I was in the field was the battery drain on the radio. Using either LiFePo4 or Li-ion 18650s even with back-up meant that if I ran FT8 for more than a couple of hours, I was out of juice. The voltage drops pretty drastically from the rated 7.4V-7.6V all the way down to 5.5V. For a small radio with low output, it draws a lot of power. Yes, one could use a larger battery pack, etc., but this is meant to be palm carry, field operation suited radio. It defeats the purpose of carrying this nifty little equipment. Given that I do need to be flight safe, it isn’t possible to carry a battery pack in a different form given the changes in flight safety regulations.

SSB Quality

The speakers on thee zBitx need a lot of love and some serious change, the audio quality is fairly poor for SSB. It is best to either use headphones, or change the speakers completely on the zBitx.

CW decode

Given the manner in which the CW code is written and the way the display is updated on the zBitx, it is a challenge to use the “automagic” decoding of CW on the zBitx.

Software challenges

The manner in which the settings are provided is a bit convoluted for me, I find the lack of setting up POTA, SOTA, or other prefixes/suffixes a little problematic. On the sBitx, changing to JJ’s 64-bit version also gave me some nice quality of life changes that I do miss in the native application of the zBitx. Given that the zBitx is powered by a Pico (W?) and not a Pi 4/5, I do not need a full-fledged operating system, but some flexibility in modding the interface would have been great.

Clean shutdown

Call me old school, uninitiated, Luddite, etc., but I do prefer a good, clean shutdown. The fact that this much like the default version on the sBitx, does not provide a clean way to shutdown makes me shiver every single time I unplug the power source. I would love a simple software version to power down the device cleanly and gracefully.

Modifications

I’ve been thinking about making numerous modifications since the first time I took the zBitx out for a spin in the field. However, mQTH and other things made it a little hard to get it going. VU3GWN had shown me his mods at one of our monthly BARC meetings. I had even co-ordinated with VU3IHK for 3D printing the parts listed below, he very kindly worked with me to make minor edits and mailed them over.

Hardware

Case with more vents

I do need to now get some nice mesh/metal gauze that can close the vents to reduce the chances of large particles getting in. And as always, here is a time-lapse of my clumsily changing the case and checking if it works.

Fans

I need to buy a 40mm 12V and either use a separate battery to drive it or I need to drive it (albeit with lower rpm) from the zBitx itself.

USB-C PD Trigger

Based on my previous post on making the most of a field ops with a power bank, VU3CER directed me7 to 9V USB-C PD trigger boards available at Punoscho as long as my power bank is capable of providing it. A quick search revealed a nice little 20,000 mAh Ambrane powerbank8 that is capable of 3A at 5V, 2.22A at 9V and, 1.67A at 9V. This makes it ideal for both the QMX and the zBitx. The video at the top of the page gives you an idea about my labour day!

Software

V2 Release

With the release of zBitx v2, there has also been a software update for V1, and the instructions are available on HF Signals webpage. I am tempted to attempt a change as you can see I am unhappy with the software on the zBitx currently. However, the discussion on groups.io seems to suggest, waiting might be a better option for now.

JJ & Gang

I do enjoy the quality of life provided by W9JES and friends for the sBitx, they’ve been working on a new versions for the zBitx and for the front panel. He did mention there will be a new version out soon based on Debian Trixie, so I shall wait for a while before I update the firmware on the zBitx9.

Next steps

Now that I have most important piece of work, i.e, a stable field friendly power source for the zBitx, if I create the K6ARK QRP mic, update the software once W9JES releases a new version, I’m good to take the zBitx out for a nice field test.

  1. Please remember, that my requirement is to have a back=pack ready setup which is also flight safe. ↩︎

  2. If you’d like to follow the full discussion and announcement, head over to the discussion group at https://groups.io/g/BITX20/topic/118916634. ↩︎

  3. I might have the opportunity to attempt one or two POTAs in the next month! ↩︎

  4. https://groups.io/g/BITX20/message/121244?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3Arecentpostdate%2Fsticky%2C%2Czbitx%20heat%2C20%2C2%2C0%2C115486030 ↩︎

  5. https://groups.io/g/BITX20/message/120456?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3Arecentpostdate%2Fsticky%2C%2Czbitx%20heat%2C20%2C2%2C0%2C114701334 ↩︎

  6. https://groups.io/g/BITX20/message/118020?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3Arecentpostdate%2Fsticky%2C%2Czbitx%20heat%2C20%2C2%2C40%2C112789718 ↩︎

  7. https://rfcorner.in/posts/best-power-supply-for-fieldops/ ↩︎

  8. 20,000mAh seems to be under the current flight limits ↩︎

  9. The wire thrown out of the balcony test was interesting, the sBitx got a couple of FT8 contacts made (very high SWR across bands), but the zBitx couldn’t pick up any signal. I’m hoping, I haven’t messed up too much with my attempts at modding the zBitx. ↩︎

Citation 🔗

BibTeX citation:

@online{vu3gljmakzbi2026,
  author = {Bharath M. Palavalli},
  title = {Making the zBitx field-worthy},
  date = {2026-05-02},
  url = {https://ham.bharathpalavalli.com/posts/20260502144921-making_the_zbitx_field_worthy/},
  language = {en},
  note = {Callsign: VU3GLJ}
}

For attribution, please cite this page as:

Bharath M. Palavalli. 2026. "Making the zBitx field-worthy", 02 May 2026. https://ham.bharathpalavalli.com/posts/20260502144921-making_the_zbitx_field_worthy/.

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