Adventures in Urban HF Portable – Part 0.75 (The Delay, Part Two)

Silencing the crickets, sort of…

My goodness, after promising a soon to follow update all of four months ago, it’s been all quiet on the blog since then. What has happened?

Well, the biggest was some departures at work that caused everything to get busy in the final months of last year. This more or less resulted in very little amount of time to play radio.

At this stage, however, it’s still something that I’m very much interested in continuing to pursue. With some consideration, the fan dipole is going to largely be impractical for this use, so I’ll focus my effort into the magnetic loop, as this will be convenient to setup on our office balcony. Build log to come on that once I’ve built it, but perhaps don’t hold your breath – I’m still yet to document the build of the lightweight Yagi that I used for the VHF Sprint back in October.

Apart from this, 2023 seems to be shaping up for some additional radio related fun. I’ve recently purchased a new car, a VF Commodore wagon, and as with all new vehicle purchases the first natural step is to jam a bunch of radio gear into them. Updates to follow with this as I build it out for general comms, some digital fun, as well as some high altitude balloon specific equipment which should be a bunch of fun.

Additionally, I’m hoping to get out portable in general a little bit more this year, so stay tuned for that.

Adventures in Urban HF Portable – Part 0.5 (The Delay)

In which fan dipoles are quick to construct, hardware is broken, and shipping from the US is slow

Almost a month with no update on the fan dipole urban HF adventure… Has cloud abandoned a new blog after the first post again? Does it really take them almost a month to build a fairly simple wire antenna? – i hear no one asking as this is an internal monologue…

No and no. let me explain.

The fan dipole has been constructed and is eagerly awaiting it’s first go on air. More will be detailed in it’s own post, but it was a quick build constructed out of some parts left over from a previous antenna project. A system for hanging it in the office window has also been devised.

The delay here is that while band conditions on 15 and 10 metres are starting to show promise, I think it’s still going to be a little while before SSB contact is possible from this location. As such, I wanted to get started using FT8. Here is where the problems arose.

A Faulty link

Earlier this year, I purchased a Digirig Mobile audio/serial interface, produced by Denis Grisak – K0TX. It’s a fantastically compact design for a Radio to PC interface, comprising of both a USB audio interface and a USB serial interface that connect to a PC with a singular cable, all packed into a case smaller than a pair of 9V batteries.

size reference for the unit, very compact – image credit:

I ordered my unit in March, and it finally arrived in May, my order having been held back so that I would receive one of the v1.9 units, instead of the v1.5 that that I ordered. Much appreciated Denis!

Upon receiving it, it unfortunately sat for several months before I finally brought it out for this adventure, where upon doing so I discovered that the device was faulty.

The audio interface component of the unit would not show up at all! multiple computers, cables, and operating systems were tried but the generic USB PnP Audio Device used in the unit failed to appear each and every time, with windows giving the cryptic message that the USB device malfunctioned, or Windows didn’t recognise it.

Digging further in device manager, the device didn’t appear under the list of sound devices, instead appearing as an unknown USB device with the message Windows has stopped this device because it has reported problems. (Code 43) A request for the USB device descriptor failed appearing in the properties for the unknown device

A Swift Resolution

Reaching the digirig forums, I found a post describing unit behaviour identical to mine. Reaching out to Denis with the information I had gathered about the fault, he quickly identified that the audio controller chip in my unit was likely faulty, and placed a replacement unit in the post. Massive thanks to Denis for getting that sorted out so quickly, especially considering that I’d had the unit for over four months before raising the issue.

That’s where we’re at now! Shipping times to Australia from the US are usually pretty slow, so I’m awaiting the unit. I’ll be getting on air with some FT8 as soon as it arrives.

Adventures in Urban HF Portable – Part 0 (The Plan)

Is this just an exercise in futility? Only time will tell

With solar cycle 25 now in full swing, this summer appears to be shaping up to give some good opportunities for HF radio contacts, and fortunately for me my amateur radio hyperfixation has appeared again while heading into Spring/Summer, rather than in March when the bands are dying down again, as it has in past years.

While operating portable or from home during the weekends should provide some good opportunities, I’d like to have the ability to work the upper HF bands at a minutes notice during the week when they’re open, which adds the requirement of being to operate from work.

While I don’t work from home, my work is quite flexible, so I should be able to fit my break times around periods where the bands are open. Being in the office though, my options for getting on air are slightly limited. The way I see it, I can either:

  1. Leave the radio at home and use my existing home VPN infrastructure to run digital modes via a connected Raspberry Pi and WSJT-X
  2. Bring a QRP radio to work and setup a compact station there.

I have some reservations about the first option with regards to how I’d handle TX timeout, and also the way in which it locks me into digital modes only, as the ability to run SSB would be much appreciated. As such, I’ve chosen to go with option 2.

Rather wonderfully, my work colleagues (shoutout systems-ade crew) have found my descriptions of some of the technical aspects of radio to be interesting, so they seem to be on board with me being able to setup a QRP station with a small antenna in the office. Bonus points if I can work some DX while they’re around!

Station Constraints

I’m somewhat fortunate that my office is at somewhat of a height (~10 floors up), and has a large window that spans the length of one of the walls. The length of this window is approximately 6 metres, which should give me couple of nice options for working on 15 and 10 metres for summer.

  • Small Magnetic Loop – This one is most ideal as it’s small to store and quick to setup
  • 15/10M Fan Dipole – Would require its 15m elements to hang down at 90 degrees at the ends to fit the space, but 10m will fit just fine.

I’ve decided to have a play with both and see how they each perform. I suspect that due to its size the loop will win out, but it’s more complex construction means it’ll be longer before I have it ready.

The fan dipole is much quicker to build in comparison, so hanging it up indoors will be the main challenge. More details to follow it it’s dedicated post.