NZ Net News 139, 17 Aug 2024

This is a free fortnightly newsletter about the New Zealand Net, which meets daily at 2100 NZT on 3535 kHz.
If you would like to be notified by email when a new edition is published, please contact ZL1NZ.
Browse our Newsletter Archive and List of Net Tips.

Featured key

By Mark KM4AHP

Here is a dual-mode magnetic sideswiper and straight key made by Ron Ayling G3YUH. This was his Master Key project in 2006. You turn the paddle and lock it down to be used as a straight key or sideswiper.

* If you have an interesting key for this feature, please send a nice clear photo and a few words describing it.

---

Photo flashback

---

sBitx v3 – a feature-packed HF transceiver from India

By Stephen ZL1ANY

Here is a photo of my recently acquired sBitx v3, along with my N7DDC ATU-100 antenna tuner (which I built from a Chinese kit which came with enclosure).

The sBitx (see sbitx.net and hfsignals.com) is a 20-watt HF transceiver designed by Ashhar Farhan VU2ESE.

It is an open-source Hybrid SDR, powered by an internal Raspberry Pi 4. It has CW and FT8 and includes such features as logging software, macros and spotting, along with all-electronic T/R switching, a fanless power amplifier and electronically selected filters. The finals are IRF510 power MOSFETs, which are about $1 each. The amp is Class E, making it efficient.

The sBitx uses techniques similar to the uSDR, which is a modification of the QRP Labs QCX range. It has compromised power above 20m. The amp can do 40W, but with some increased risk to the finals if mismatched into the antenna load.

The receiver is a hybrid superhet design with a passive-FET KISS mixer and a 7-element 8-crystal filter. The receive noise figure is 15 dB with an IIP3 of +28 dBm.

Current consumption on receive is 600 mA (much of which powers the Pi 4) and on transmit it is 9A (running on 12V).

It is available fully built, as in the picture, but also as component boards, and in particular a Pi HAT
which would be good for a homebrew design.

It has a touch screen, which is a little fiddly due to small size (and big fingers) but there is an active user group and various options for configuring the hardware interface and adding 3rd party software. The rig has a CW decoder, which seems to work as well or better than most.

You can access the sBitx via a web interface and ethernet or Wifi, and it has Bluetooth for wireless audio (albeit with some latency which makes that pretty useless for CW unless you use a keyer with its own speaker rather than the transceiver’s sidetone.)

As you might be able to see from the photo, I tried it out on NZ Net a couple of weeks ago and got good signal reports from ZL1NZ.

Looking forward to working some of you using it over the next few months.

For a demonstration of the sBitx, see the video later in this edition.

---

More Morse Cram in Christchurch

By Kelvin ZL3KB

For the second time this year, Branch 05 Christchurch gathered Morse Wannabes for a weekend of Morse immersion in the same style as HamCram.

The two-day course started from scratch, participants were required to come along with no preparation, so we wouldn’t need to unravel bad habits. Teaching was done with sound only, and no Morse sending was done by the students.

However, some activities required the students to send Morse characters to their group, so a few Morse keypads were designed, with only the letters used in the Koch Method MorseCram course.

The weekend resulted in a strong desire to carry on the code practice afterwards, so we are now running Morse classes every Tuesday evening at the clubrooms.

It is hoped to run another MorseCram course next year. Many thanks to Cath ZL3CATH for feeding us, and Des ZL3AK and Richard ZL4FZ for assistance in a successful weekend.

---

Letter from a JRC fan

Hi Neil, thanks for the online magazine (NZ Net News 138). It is always very interesting to read news from a past very close to us, as in the advertisement for the JRC JST-100.

I also had it for several years. Then, to improve and refurbish the station, I switched to the JRC JST-245 which I paired with a JRC NRD-545 DSP receiver (pictured below).

The JRC-100 was a very interesting radio, both circuit-wise, built really well, and also in terms of sensitivity and audio reproduction.

Moving on to the JRC-245, I found some improvements, mainly due to the advanced technology and design improvements, basically, the receiver part remained practically unchanged.

You will have realised that I am a fan of this brand of radio, which unfortunately has not been on the amateur market for several years.

Also in the photo, you will see a maritime receiver, I think it was the last one used for ships and I am referring to my JRC NRD-301A.

I keep it jealously, the audio playback is excellent, I do several hours of listening without getting tired.

A pity I can no longer take advantage of new equipment of this kind.

– Tony IK0PHU

---

Morse challenge

Please send your answer via radiogram or email to ZL1NZ.

Answer to previous Morse Challenge

The coast station was 3DP Suva Radio, and it was holding traffic for 9VYT (container ship M/V NOL Diamond). Correct answers were received from IK0PHU, VK2KJJ, VK3DRQ, ZL1ANY, ZL1AYN and ZL1PX.

---

More musings: defining mechanical keying

By Chris G5VZ

It was interesting to see that you reproduced the text by Graham G3ZOD about the new ADIF standard proposal on types of keys (NZ Net News 138).

As you can guess, there has been a lot of discussion about this in the FISTS Management Team here in the UK. It is interesting that a topic like this not only brings up a diversity of points of view (as in, if there are six radio amateurs there will always be seven opinions) but also illuminates some prejudices which otherwise remain dark secrets.

One aspect of this has been the divide between bug users – mostly devotees of the bug – and the bug-free community. But also the definition of what is a ‘mechanical key.’ It’s interesting that the word mechanical means ‘as done by a machine.’ I think that should answer the question being considered for ADIF and probably clubs promoting ‘mechanical key days’ and so on. The machine may be simple or complex but what it does is always mechanical.

It seems reasonable to me – and in alignment with the views of many organisations – that the concept of ‘mechanical’ is defined as the operator causing their key to create a signal by a physical action. That includes using fingers and thumbs but also – for instance – blowing into a tube, using breath to activate some kind of switch. The nature of the signal created is determined by the operator’s actions: element length, spacing and suchlike.

Back to bugs, and a bug key is by definition semi-automatic but usually considered (rightly) a mechanical key. The BUG Users Group allows bugs to be fitted – for instance – with optoelectronic dit sensors, replacing the make-or-break contacts. Although electronic, the sensor does only what the metal contacts do, just better. (See the Optidit by WO6W for Vibroplex keys which, I’m told, Vibroplex may soon be selling.)

On my old Vibroplex Lightning, sometimes I feel lucky to make a 5. But the same model, with Optidit fitted, will send regular, well-formed dits for almost 40 seconds! How do we categorise that? I don’t think it stops the key being ‘mechanical’ in any way – it simply provides a much better switch.

A touch key – single or double – is the same. This type of key causes no end of controversy in this neck of the woods. Some, of course, are simply paddles connected to a keyer making them not mechanical in the sense we are meaning – perhaps ‘assisted’ would be a better word. A touch-key – capacitive sensor, perhaps – that uses the action of the operator to generate a signal is unassisted and, by definition, mechanical. Whether the ‘contacts’ are closed by a simple switch circuit or a more complex touch-activated circuit doesn’t matter: the operator is creating the code.

If the key is connected to an electronic keyer, then that changes everything. That is, when the code is created and its form are determined by a circuit.

I’ll clamber down from my soapbox now, but I do think this is an important aspect of Morse and CW on the air, well worthy of discussion.

---

Video: CW features of the sBitx v3

---

Net tip: QNG

Here’s an important Q Signal which is used occasionally on NZ Net.

QNG means “Please take over as Net Control”.

If the net control station is having trouble running the net (it could be any reason, from high QRN to high SWR) or has to deal with an urgent matter requiring them to close down, they may ask another station to QNG.

Please note that there is no time limit on this – the new station becomes the net control for the rest of the net (or, until they ask another station to take over, if necessary).

There is also a limited version of QNG. If Net Control sends QNG1, it means “Please take over as Net Control and call for check-ins, but then turn it back to me as soon as you have made one call for check-ins but received no response.”

---

Advertising archive

---

Suggestions?

If you have suggestions on how to make the NZ Net better, or things you’d like to see covered in these updates, please contact ZL1NZ. You might even like to write something for the newsletter.

Thanks for reading, and I hope to hear you soon on the NZ Net!

—

Neil Sanderson ZL1NZ, Net Manager
New Zealand Net (NZ NET)
3535.0 kHz at 9pm NZT Mon-Fri