HF Portable in VK7

Hf_portable_-_edited

For the Easter long week-end I was down in Tassie (VK7) at Dilston just outside Launceston (QE38mp). I'd planned to finally try some radio on this trip after visiting VK7 a several times in the last couple of years. No matter what I was going to take a radio on the plane with me and hope for the best. Originally I was hoping to just do 2m with a nice little 2el 2m beam I designed/built. But I didn't get it to where I wanted it in time.

However, not long before I started getting keen on the idea of HF portable – purchasing a squid pole etc. So in the end I made a decision I would attempt HF portable in VK7 at my inlaws – especially seeing they're on a few acres and thereby should be relatively quiet.

I had a few ground options with me, and also two antenna options, but in the end this is what I went with:
Antenna: End fed inverted V with 25m of wire supported in the middle with 9m squid pole
Ground: Short wire connected to a tent peg and in the nice moist physical ground; and, another wire with alligator clip atteched to a wire fence about 100m long.
Radio: FT-817ND

To my pleasant surprise, this setup provided full tuning across all HF bands I'm licensed for (80m, 40m, 20m, 15m and 10m). Therefore I was receiving strong signals from all over the world and even attempted to work a strong K7 station – but alas all they responded with was QRZ QRZ.

But I did have a nice chat with a few ZL stations – my first non-VK contacts due to my minimal HF experience – as well as VK7 and VK3. Also was hearing stations happily in VK2 and VK4.

A few logistical points of this adventure were:
– To transport the squid pole on the plane, I simply purchased two 660mm x 60m postal rolls for the post office ($5) and cut one in half and gaffer taped it to the other. I then packed each end of the squid pole with a bit of newspaper and shoved it in the tube. Used electrical tape to seal each end cap ensuring safe passage for the squid pole (no damage at all);
– I rang the airline (Virgin Blue) to check on the legalities of taking Sealed Lead Acid (SLA) batteries on the plane. They informed me that I was definitely _not_ allowed to take SLAs on the plane in any fashion. As a result, I packed my SLA charger and then ducked into Jaycar on Brisbane street in Launceston when I got there and grabbed a new little 4Ah 12V SLA – which I've left at the in-laws for next time.
– The radio, tuner, microphone and wires pretty much all fit in one of the snap lock type containers you can grab from the super market. I wrapped the radio and tuner in a couple of tea towels each for padding. I might try and get a photo of this next time I venture out.

Other than those two points, the only other 'issue' I had was that the guide eyelet at the tip of the squid pole (that I run the antenna wire through) came off at my first attempt of standing the antenna up. Disappointed but not defeated, I pulled out my trusty roll of electrical tape and stuck it back on. There it stayed and was not an issue for the rest of the time. However, I guess I should revisit that soonish.

The photo was taken unawares to me by my XYL. She's done a great job as it shows the scale of things with the squid pole. Basically the antenna is a triangle (being an inverted V) with one anchor point being where I'm seated. The apex of the triangle is then at the top of the squid pole with the other anchor point being out of frame to the right of the squid pole an almost equal distance (the apex angle being obtuse). This setup was thanks to some guidance from Peter (VK3YE) and the nice diagram he provides here.

Well, there you have it. I'm now keen to get out for some more HF portable action and so will hopefully have some photos or video for you sometime in the next few weeks – when time finally permits.

Hope you all had a great Easter.
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2m FM PSK Test

Last night I organised to have a play around on 2m FM with digital modes. I was curious to see two things:

a) Did it work; and
b) How well did it work.

I was pretty sure it would work – after all it’s just tones – but I wasn’t sure if there’d be any noticeable benefit. In the end I’d tee’d up a sked with Steve (VK2ZSZ) over in Queanbeyan at QF44op with me being at QF44mp. This was going to be an interesting path as it would require the signals to traverse at least one significant ridge line between us (probably an additional 200m ASL at it’s peak). Also, Peter (VK1NPW) had mentioned he’d attempt to join in but I was very dubious if that would work because I knew from experience that that path was a struggle (almost 100% unreadable) with voice – he being at QF44mo.

So in summary, we planned to try some PSK31 with the following stations all on basic vertically polarised antennas:
  • VK1HOW – QF44mp – 20W on a FT-7800 – 0km
  • VK2ZSZ – QF44op – 5W on a FT-817 – 15km
  • VK1NPW – QF44mo – 10W – 4km (that’s a surprise, I thought he was much further than VK2ZSZ)

What I found was that I was receiving VK2ZSZ at S4 with almost full quieting most of the time and 100% copy with close to 40dB S/N. VK1NPW was being received at S2 (about where the noise floor was – squelch was fully open as you’d expect) and I could copy him but had to keep manually adjusting the frequency in fldigi – and no S/N reading was offered by fldigi unfortunately. With VK1NPW’s signal I could also still see noise in the waterfall so definitely not full quieting.

As for signals between VK2ZSZ and VK1NPW, generally VK1NPW could not receive VK2ZSZ.

So what was seen was that we could get a very clear copy using PSK31 over 2M FM where otherwise voice would have been a real struggle (and at least with VK1NPW it would have not been possible at all). I would have also liked to switch over to simplex voice and try just for comparison, but we ran out of time – I might try and set this up soon just as a quick test with them both.

Therefore, the benefits (and enjoyment) of digital text based communication can even be realised on FM. Further, it was great to see the path over to VK2ZSZ as that was definitely a case of knife edge refraction and was a good enough path to even allow us to execute PSK-250 (unfortunately wider modes met a limit with computer processing power).

Thanks to both Steve and Peter for supporting me in this experiment. Hopefully there’ll be a few more in the future. 🙂

My First Transmitter (ponderings)

They say one of the juggling things one does when building their first transmitter or receiver is between two key things:

1) Simplicity – to ensure success;
2) Usability – to ensure it's worthwhile and doesn't end up on the shelf collecting dust.

To address item 1 I want to build a crystal locked SSB transmitter for 40m (I would have gone CW for greater simplicity, but I'm only just learning CW – slowly). However, there is a risk building a transmitter which is not frequency agile when you live in Australia – vs. Americas/Europe – with a lower AR population. That is, you may find no one is ever on the frequency your rig is built for and you can't just simply tune to another frequency when you find someone and jump in and have a chat. Thereby, you sacrifice the usability element and potentially end up just placing the resulting item on the shelf.

However, what about WSPR! It's only on one frequency per band, and there's always someone listening – more or less!

So, my plan has evolved into a crystal locked WSPR transmitter for 40m. This is also nice and simple on the audio input as well as it can just take the audio from a computer output. I was even contemplating building a simple VOX circuit into the audio line to do the PTT – but maybe that's over complicating things and I should just add a simple switch that can be controlled from a computer via serial port – such as with my current digital interface. Maybe, I might even add a simple mini-din socket like used on the Yaesu radios so that my interface can just plug straight into that for starters.

Really then, it looks like I can come up with a simple transmitter through just having a locked oscillator and relying on audio from a computer – as opposed to a mic requiring amplification etc. Ideally, I'd love to do a direct conversion crystal locked transmitter (for minimum stages), but I'm currently struggling to find a suitable crystal so I may have to look at a single conversion transmitter in the end – but we'll see.

So currently it's looking like my transmitter would be looking like:
* Direct Conversion
* Crystal locked
* Balanced Modulator using an NE602 – or maybe I could make it simpler by just using a two diode balanced modulator
* Audio in from computer
* Simple transmit switch – possibly controllable externally
* Oh, and some kind of filter to convert the DSBSC to USB, and then possibly a pi-coupler to the antenna connection
* And power wise, I'm happy with 1W as I know that'll yield results with WSPR – as will 500mW like I've been using recently

But in the mean time for a bit more reading, one of VK3YE's video about his DSB 30m WSPR transceiver has pointed me to here:

Have a good week-end all – maybe I can get some photos taken of my FSM and digital interface (but no promises – we know how long it's taken me already).

My First Transmitter (ponderings)

They say one of the juggling things one does when building their first transmitter or receiver is between two key things:

1) Simplicity – to ensure success;
2) Usability – to ensure it's worthwhile and doesn't end up on the shelf collecting dust.

To address item 1 I want to build a crystal locked SSB transmitter for 40m (I would have gone CW for greater simplicity, but I'm only just learning CW – slowly). However, there is a risk building a transmitter which is not frequency agile when you live in Australia – vs. Americas/Europe – with a lower AR population. That is, you may find no one is ever on the frequency your rig is built for and you can't just simply tune to another frequency when you find someone and jump in and have a chat. Thereby, you sacrifice the usability element and potentially end up just placing the resulting item on the shelf.

However, what about WSPR! It's only on one frequency per band, and there's always someone listening – more or less!

So, my plan has evolved into a crystal locked WSPR transmitter for 40m. This is also nice and simple on the audio input as well as it can just take the audio from a computer output. I was even contemplating building a simple VOX circuit into the audio line to do the PTT – but maybe that's over complicating things and I should just add a simple switch that can be controlled from a computer via serial port – such as with my current digital interface. Maybe, I might even add a simple mini-din socket like used on the Yaesu radios so that my interface can just plug straight into that for starters.

Really then, it looks like I can come up with a simple transmitter through just having a locked oscillator and relying on audio from a computer – as opposed to a mic requiring amplification etc. Ideally, I'd love to do a direct conversion crystal locked transmitter (for minimum stages), but I'm currently struggling to find a suitable crystal so I may have to look at a single conversion transmitter in the end – but we'll see.

So currently it's looking like my transmitter would be looking like:
* Direct Conversion
* Crystal locked
* Balanced Modulator using an NE602 – or maybe I could make it simpler by just using a two diode balanced modulator
* Audio in from computer
* Simple transmit switch – possibly controllable externally
* Oh, and some kind of filter to convert the DSBSC to USB, and then possibly a pi-coupler to the antenna connection
* And power wise, I'm happy with 1W as I know that'll yield results with WSPR – as will 500mW like I've been using recently

But in the mean time for a bit more reading, one of VK3YE's video about his DSB 30m WSPR transceiver has pointed me to here:

Have a good week-end all – maybe I can get some photos taken of my FSM and digital interface (but no promises – we know how long it's taken me already).

VK1 40m QRP WSPR Challenge

Screen_shot_2011-04-11_at_6

Today I sent out an email with details for a WSPR challenge in VK1 (ie. QF44jc to QF44qu). The challenge being who can send a WSPR packet the furthest, and who can receive a packet from furthest away. It's then also broken down into three categories according to power of transmitters (500mW and below, 5W and below, and more than 5W).

The challenge goes until Friday midnight (local time) and started this afternoon. It's early days yet, but it looks like as people come home tonight it's kicking off. 🙂

Oh, there's also a bonus challenge of who can receive the most VK1 stations.