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There's yet a third issue with the zBitx: It's likely that RF digital noise is getting coupled into the receiver, raising the noise floor and reducing SNR, as well as creating serious hum from the speaker audio out.

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I'm guessing that there's a decent, maybe 50/50, chance that all 3 issues are fixable.

But these might not be quick fixes.

1. Some insulated copper foil shielding under the display and maybe between PCBs might help with the internal RFI. ?Perhaps more bypass caps might be needed as well.

2. Additional bypass caps and a different drive level or output coupling for the Si5351 clock chip might reduce the 2 MHz spurs to under legal limits.

3. And junking the current rat's nest of layers of sample processing + keying code, and replacing it with CW specific sample processing routine running on a priority thread locked to a cpu core, plus slightly better interrupt handling, or perhaps an even simpler fix, should fix the CW keying latency.

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I plan on waiting to see if others who are more experienced with these bitx designs can fix some of these issues before I spend more time digging in myself.

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But if you want a working radio out-of-the-box, you might want to wait for version 2 or 3 of the hardware. ?

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IMHO. YMMV, 73, Ron, n6ywu

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That does it for me.? I am returning my zbitx unopened as soon as it arrives.? ?How disappointing this whole episode has been.? ?Now I will find out how good they are about refunds.? Thaks for your help and expertise.? Doug

I would not make any assumptions about external keyer input working until some proper software fixes have been implemented and properly tested.

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The last update was not it. ?It appears that other outside software developers had to step in and fix his last project. We may need to wait for the same thing to happen with the zbitx.

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I still have hope for the basic concept. ?But it's currently a project, not a product.

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- Ron

I assume that using a straight key or external keyer works ok?

Hi Doug,

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Keyboard CW on the zBitx seems to works just fine. ?I tested that.

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It's the CW *keyer* that's not working, and my guess is that the odds of the keyer getting fixed soon are only 50/50. ?A proper fix might take a lot more time, and/or potentially require a hardware mod.

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I'm also hunting down a nasty Tx spur, possibly caused by intermodulation of the carrier with digital noise. ?That could potentially be the more serious issue. ?Don't know yet.

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- Ron

Ron, do you think they will get a fix for cw?? I am a 99% cw operator and if the radio won't do cw, it's basically worthless to me.? I have to say that so far. I am extremely disappointed in the zbitx.? I want it to be a good radio, but am losing faith in that happening.? ?Do you think the cw problem will ever be fixed?

Hi Ron, it's an intriguing little machine!

I read the user manual here

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Now I understand what you said (several times! Ha) about SSB/AM remote support.? Presently it will take voice only from the local microphone input, not via UDP.? Hopefully that's a software issue.

Can't believe how much is packed in there for $200.? Power of open source software.



How did you look at the TX signal?? The manual mentions a 2 Tone mode.? Wondering if you tried that.? And which other modulations?

73, Cliff K6CLS

Still testing my new zBitx.

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A software update may be necessary to fix CW. ?

I'm not sure the latest updates are finished or well tested for CW. ?So I plan on waiting a bit before I try updating the software. ?

The update process is described in the online zBitx manual, and require connecting the zBitx to the internet. ?The Pi in the zBitx is running standard Raspberry Pi Linux. ?You can log into it and type shell commands.

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Receive on my zBitx seems noisy. ?

There is a pulsing noise from the speaker, even with the antenna disconnected and both IF gain and audio volume turned down halfway.

Transmitter harmonics look OK; but there are some other Tx spurs that need more investigation.

FT8 Rx and Tx both seem to work on my zBitx. ?But I see more FT8 decodes using my HL2 on the same antenna.

The zBitx control UI seems a bit clunky to me (but then again, there are those who don't like the UI of my iPhone apps :-)

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- Ron

Thankyou Ron.? What do I have to do to fix the cw?? I have one that is supposed to arrive tomorrow.? ?As long as it meets FCC specs it's good to go.? Do you like the radio?

Apologies for the cut-and-paste errors in my previous post.

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My zBitx came with 1.0.6.

But I'll probably update soon to get the latest CW latency fixes.

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My first tinySA measurement showed the 1st harmonic is 44 dB down from the carrier.

Thus barely meets FCC regulations ... ?If I measured correctly (though 50 dB of attenuation).

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- Ron

What operating version did it come with? 1.02??

Received my zBitx last night, via DHL.? Powered it up today.? Seems to work.

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https://www.hfsignals.com/index.php/zbitx/

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About half the price of an Hermes Lite 2, and it includes a Raspberry Pi Zero 2 W running Linux for the radio UI.

Also slightly smaller and lighter than my HL2.

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I can ssh into it's Pi Linux, modify and (re)build the software (open source on GitHub).

I can also display the UI in a web browser, such as Safari on an iPad (including specrum & waterfall, etc.)

So one can run this radio from a colocated iPad via two ethernet adapters (one for the iPad, one for the Pi Zero).? Audio out can be piped over the net, but not microphone input

So it can't be used for remote SSB operation. Only keyboard CW and FT8 remote.

Half the price of an HL2, and that includes a Raspberry Pi Zero 2 W running Linux for the radio UI.

Also slightly smaller and lighter than an HL2.

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I can ssh into it's Pi Linux, modify and (re)build the software (open source on GitHub).

I can also display the UI in a web browser, such as Safari on an iPad (including specrum & waterfall, etc.)

So one can run this radio from a colocated iPad via two ethernet adapters (one for the iPad, one for the Pi Zero). ?

Much easier on the eyes than operating via the small touch display.

Audio out can be piped over the net, but not microphone input; so no remote SSB operation.

Only keyboard CW and FT8 are remotely operable over the net.

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Includes WiFi capability, a Keyer w/ macros, and FT8 built-in.

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Receiver is a semi-wideband (for the 24 kHz wide spectrum) analog SSB design (which the Pi then further DSP filters for narrower bandwidths).

Uses a 24-bit ADC (ENOB is around 15 bits according to Cirrus Logic WM8731 data sheet) in mono mode.

Speaker seems decently loud.

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Needs a 9V power supply for 5W.

I'm currently running it off of 2 LiFEPo4 18650's at 6.5V, so only at 2W Tx.

Or I could use an 8 cell AA holder with 2 dummy cells for about 9V.

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For under $200 (not including any new VAT), vastly better than the uSDX+ V2.

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Ron

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Thanks Ron.? Yes but you have? $235 left to spend on those items.?

Ahh, huge difference in the diameter of the coils on the antennas.? ?Nice catch.

73, Eric NF6S

ex WD6DBM

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You worked Tuvulu with an AX1?? Wow, I am impressed.?

73, Eric NF6S

ex WD6DBM

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It's free standing, and breaks down to 6" pieces.

If coat pocket sized and free standing are your requirements, What's the competition?

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Maybe the eBay $20 to $40 5MHz-55MHz Mini QRP Shortwave Antenna with Tuner Adapter?

And that still needs a mounting bracket and tripod or base of some sort.

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Ron

I am not surprised.? ?Care to tell us why you are making the purchase?? I just couldn't justify the cost for what it is.