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Dear all,

today I took the QMX for a hike and did a short SOTA activation of HB/BE-110. The aim was to test a very minimalistic setup for use on summits, which I otherwise would not activate (eg. limited space + too many people around):

- the (low band) QMX fixed to a hiking stick (zip ties do the job)
- a small loaded vertical for 30 m, around 120 cm max. length (made from stuff I had lying around)
- 2x 3.5 m counterpoise wire
- a USB-Powerbank for power supply (with USB-C PD trigger board to get 12 V out, works like a charm)
-CW key/earphones

Then I stopped thinking to much about antenna efficiency and just gave it a try....and was pleasantly surprised: I got 6 QSOs within the first 10 minutes of the activation...that's very OK for me. The RBN spots also looked quite decent, so I'm pretty sure this setup will do its job in the future.?

The QMX itself performed well, except the SWR protection kicked in unexpectedly several times and I had to restart. Next time I will only use the SWR protection feature when tuning the antenna and turn it off after. Let's see how this will work...

Hope to see you on air soon, maybe also with your "QMX on a stick" ;).

Best, Matt (HB9HWI)

?

?

That is fabulous! Thanks for sharing how simple an activation could be!

73 de w2tef

What were you using for the computing device for wsjtx ?

Hi Larry,
I did not use WSJTX, is was a CW activation.

Best, Matt

Matt, thanks for posting this. It's quite encouraging to see what can be done with minimal equipment.

FYI, you may already know this, but when the swr protection kicks in, a restart (assuming that means power down, power up cycle) is not necessary. It can be reset by simply pressing the menu button (long press as usual), then immediately exit the menu with the other button as usual. WA-LA, you're back on the air.?

73!

Roy?
KI0ER?
Littleton, Colorado USA

Hi Matt,

perfect setup for the next QCX WARC Party or Challenge.? We would love to work you there.

Martin
DK3UW

Brilliant! I love it. Can you tell me about your USB-C trigger board? Did you make or buy?
Thx
Matt

Nice setup. This gives me ideas for the station I want to carry on hiking trips in the mountains with the YL.

73!
Kevin
N8MXL

Fantastic.
The spirit of ham radio !

--
- 73 de Andy -

What kind of usb-c converter are you using??
I tried simple usb-a power bank (5V out) and dc-dc buck to step up; worked surprisingly good for receive (no additional noise) but it would add a terrible noise on tx, also audible in the sidetone. Not sure why, maybe it was overloaded :/
Anyway, I'm still looking for an option of powering it with a small, cheap power bank as the QMX is not current thirsty.

Hi Matt,

the trigger board is bought (~10 USD if I remember right) and I use this one:

Just check Google/Amazon for ZY12PDN, I'm sure you will find something. But please remember, you will need a Powerbank that supports the Power Delivery (PD) protocol and the output voltage/power you need. PD options are 5V-9V-12V-15V-20V, 3-5 Amps, but not all powerbanks can do this.

Another word of warning: Not all powerbanks provide a "clean" output. I have one powerbank with no issues at all, but another one introduces pretty noticable noise. To work around the isssue, I added some capacitors and a choke at the output of the trigger board (FYI: the choke had actually no effect, the capacitors did the job). In the end, it looks like this:



Hope this helps,
Matt

There are ready made usb-pd to 12Vdc cables available on aliexpress for just a single-digit dollars, shipping incl. I guess I'll give it a try. And yes, the pd capable power bank is needed for that.
Anyway, I'm still thinking of that dc-dc for a cheap power bank - I've got plenty of those made of single 18650 cell (many companies used to give them away as their promo stuff) and since they are about 2Ah of juice - it's not bad for QMX.

Thats cool.
yesterday someone posted a Qrpbuilder vertical antenna like that for 40&20. So I grabbed my junk box and built one like it just for 20m. I used wire for the element but it works hanging from a limb. one thing they mentioned was the use of a snap on 31 material ferrite with 5 turns of feed line to choke off? common mode currents.

I wondered if you had any issues with that connecting directly to the QMX and maybe thats why your swr protection was acting out.
--
regards,
Bryan, N0LUF

Hi Bryan,

the common mode current issue was also on my mind, but on the other hand I really wanted to connect the antenna directly to the QMX to make everything as compact as possible. I may go out for another activation next week and will disable SWR protection after tuning the antenna. In case everything works fine, I'll probably live with it "as is". I'll let you know how it went.....

Best,
Matt?

On Fri, Feb 2, 2024 at 07:20 AM, Matt - HB9HWI wrote:

(with USB-C PD trigger board to get 12 V out, works like a charm)

Hello
there was a posting in this group warning from using a USB-C PD Decoy with the QMX because of possible damage due to the voltage ramp accomplished by the PD Decoy during startup. I include a copy & paste of the message I mean. 73 de dl2arl

Matt,
A friend of mine was on cover of qst with a similar back pack setup.? I emailed him and asked about that.? he connects his antenna directly to the radio and said that since there was no coax to radiate he did not use a choke. he uses a drag wire for counter poise and points it toward the station by walking away.?

Ill have fun playing with mine.
--
regards,
Bryan, N0LUF

@DL2ARL
Thanks for pointing this out. Seems I have been lucky so far...and if I think about it, its probably by chance. Routinely, I connect my trigger board first to the powerbank and then I connect the transceiver. By this time, voltage negotiation seems done and the QMX does not see the 5 V to 12 V step anymore. Unfortuantely, I can't edit my initial thread to highlight that this sequence may be important to not kill anything.

So for everyone who is still reading: If you plan to use USB-PD to power your QMX, first connect the trigger board to the powerbank, wait some seconds until voltage negotiation is done, then connect the QMX.

@N6HAN
Correct, it's a BNC connector for RG58. It's drilled open (a little) to match it with the 6 mm brass tube + heat shrink (to isolate the whip from ground). That's basically the base of the antenna. In the meantime, I played around with the coil "design". Because it worked so well on 30m, I wanted to have the option to switch coils and operate on 20m, 30m as well as 40m. Below a picture with some comments.

I did another short SOTA activation with the QMX this morning on 20m, and again it worked amazingly well. 12 QSOs in 15 minutes. And with the new firmware 017 I did not experience any glitches at all. Smooth CW operation. Thumbs up, Hans! For sure many more QMX SOTA activations will follow.

Best,
Matt

G'Day Matt
USB Power - May be worth noting that if you wriggle the connector & there is the slightest bad connection, then the Voltage negotiation sequence will start again..!!
Rob
VK5ZIK