All posts by vk5fo

WX Sonde

A short sharp and shiny post !

There’s been a clear increase in interest in tracking and chasing the Bureau of Meteorology radiosonde launches here in VK5. Many have been tracking these on tracker.habhub.org and aprs.fi, and there have been quite a few new faces sighted near sonde landing locations!

to this end, I have set up a mailing list where items such as RX ground stations, chasing, and chasing co-ordination can be discussed.  This will also help avoid situations that have been encountered recently, where people have travelled quite long distances to find a sonde has already been recovered.

If you are an active RX station or a chaser we would encourage you to subscribe to the VK5 WX Sonde list.  All new members need to be approved before posting, and that will usually be done within a day or so.

For those new to this activity, the following resources will help:

Launches out of Adelaide occur twice a day, at 8:45 AM and 8:45 PM. The automatic sonde receiver stations usually detect the sonde shortly after launch, and upload telemetry to the HabHub Tracker ( https://tracker.habhub.org/#!mt=roadmap&mz=7&qm=6_hour&mc=-34.13946,138.42875 ).
Mt Gambier launches occur on Mondays and Thursdays at 8:45AM. Launches are also performed from Woomera and Ceduna, though we don’t currently know the schedules for these sites.

The Mailing list was established so that the Various RX station operators can discuss any issues and or set-up hints and tips.  For the Chaser, the list can be used to co-ordinate and notify when you intend to chase and to notify  when you actually find a Sonde.

2017 Summer FD

This year,  for something a bit different the FD was never about building a full-on 4 band station and going all out for a big score – it was all about doing more with less.

We (Me, Bob VK5FO and Ray VK5RR) teamed up with Andy, VK5AKH and went QRP portable and went for a “nice” hike up to Black Hill Summit – a summit that is a hike in – and at 460M above sea level in PF95ic

We met down the bottom of the hill about an hour before the start and packed up the gear and antennas and away we went

We were taking gear to get us on the air on 4 bands for field day – 6m, 2m, 70cm and 23cm.

After nearly an hour, we finally made it to the summit at around 01:10 UTC just after the start time and proceeded to set up Antennas and Radio’s

Here you can see the Antenna’s – 1/2 Wave Vertical for 6m on the blue pole, and on the Camera Tripod, you can see the 11 Ele on 23cm, the 6 Ele on 70cm and the Slim Jim for 2m.

Andy making a contact on 6m with the KX3.

The summit, while it doesn’t offer great views has shade! which makes for a pleasant place to operate from.

Did I say minimal station set-up.  Here I am with the KX3 and you can see the 70cm XVTR and batteries in the foreground.

We were set up pretty much at the old trig point – I say old, because someone has ripped it all out of the ground at some point and built a pile of rocks adjacent to it on the walking trail.

The aim of the day was to enjoy the hike up to the top of the hill and play a bit of radio and within an hour or so we had contacts on all 4 bands.  It was all about getting out for a few hours, and getting a few contacts and handing out contacts to the other stations who were also out and about.

As far as FD goes, it is a decent location for a minimal set-up basic antenna’s that we carried in, and very modest power  on all bands – we had 5w on 6m, 2m and 70cm and 3w on 23cm.  It truly is a case of “height is might” when it comes to VHF/UHF and above.

Mid-afternoon we packed up and headed back down the trail.

It doesn’t look it, but it was a decent hike – with about 2km each way and 250+M elevation change.  Coming back down was a bit quicker it was only about 40 minutes. Here we were about 5 minutes from the bottom.

 

We had APRS running on the Handheld while hiking in and out.

At the end of the day, I logged 16 contacts for FD, and Andy logged 21, in the 3 hours or so we were at the Summit.

As we were operating from Black Hill, this also qualified as both a SANPCPA and VKFF Activation.

 

VKFF-1683 Anstey Hill Recreation Park

Managed to find a bit of time and got out to activate one of the new parks as a first activator this afternoon.

With good early spring WX I packed up and headed out.  After having a lot of reports of the bands being well and truly on the decline, I packed the amp as well.

We headed around to the park and set up near the top of the range off Range Rd,  While it offers elevation, it also has a very nice 415Kv transmission lines running right across the top of the park and I was hoping it would not be too noisy.

Planned on a PSK and SSB activation and set up initially on 20m.  Had a few issues but finally managed to get everything working and started calling CQ on PSK31 on 20m,   at around 06:45UTC

anstey-hill-setup
The Shack for the activation

No luck at all – called for about 15-20 minutes and not a single response, so dropped that and went to SSB.  Knowing things were probably not too good, I had the HR-50 amp on and was running around 40w

Posted a spot and called and first call was replied by F1BLL. over the next 20 minutes worked VK4, ON4 and VK6 before moving down to 40m

It was a fairly constant response on 40m and worked callers from VK1, 2, 3, 4, 5, 6 and 7!

In the mix today, there were a couple – well 3 P2P contacts – the first with Phil, VK6ADF operating from VKFF-1446 on 20m then the next was with Gerard VK2IO from VKFF-0048 on 40m and then just as I called for final contacts, Phil, VK6ADF again from VKFF-1446 this time on 40m.

By the time we finished chatting with Phil, the sun was down and the light was rapidly dropping, it was a mad dash to pack up and walk back to the car in the last light.

Last light while Working Phil, VK5ADF
Last light while Working Phil, VK5ADF

At the end of the day, there were 48 contacts in the logs making the very first activation of this park a big success.  Those HT lines – well, not such an issue – sure, there was a little bit of noise, but hardly anything to cause issues.

This activation was the first time I used the VK-Port-a-Log for all logging.  Wow, what a difference it makes vs paper logging – much easier, especially considering that when I got home it was trivial to send off the logs to Paul for upload to WWFF and also import into my other logging program for upload to E-QSL, Clublog LOTW etc.

Seriously, if you have not tried it- give it a go on your next activation!

It was a great day to be out playing radio in a park!

Loops, Verticals and Inverted V’s

Over the last few days I had the opportunity to borrow a 40m Transmitting Magnetic Loop Antenna with a big thanks from Steve – VK5SFA for the loan of his 40m loop so I could conduct some comparisons.

We were at the shack in PF95wu where I have the GAP Challenger Vertical and where I could put up my portable 40m Inverted V antenna.

VK5SFA 40M loop
VK5SFA 40M loop

The loop is physically quite small  at only about 1.6m in diameter – and as you can see it was mounted on a tripod with the bottom only 1.8m off the ground, and as far away as my coax would allow from the shack – which was about 10 or 12 Metres.

Gap Challenger Vertical 80-2m
Gap Challenger Vertical 80-2m

The Gap Challenger, which has been put to use as the primary RX antenna for the KiwiSDR – was one of the comparison antenna’s used over the few days.

For the TX experiments I used the KX3 and HR-50 Amp and was transmitting at between 40 and 55 Watts of power.

Observations – the Loop

The bandwidth of the loop was quite pronounced – tune the loop, tune the RX across the band and it was pretty obvious – about 40khz wide.

TX – well, it was nowhere near 40Khz wide – more like about 12 or 13khz 1.5:1 VSWR bandwidth.

The first night, we had a bit of rain earlier and the ground was a little damp.  We found it impossible to actually tune the loop – best we could get was about 4:1 VSWR on TX.    The next night it was much better!

Tuning – well touchy is an understatement!  The tuning is manually done via an insulated rod – and 1/4 of a turn was like 40khz!  It was a case of tuning for maximum RX noise, then some careful fine-tweaking to get it there.

RX Bandwidth

The Loop was tuned to 7.140 and plugged into the SDR

40M loop on SDR
40M loop on SDR

Without changing any settings on the SDR, the Vertical was plugged back in.

40m-vertical

IT is pretty obvious as to the RX bandwidth and how sharp it drops off away from the centre frequency.

Click on both Images to see full sized.

Usage

I made use of the Loop to talk during the day – local, single-hop contacts (VK2, VK3, VK4) – and when 40m is open, it is open – 59 contacts – no real difference between any antenna.  DX – I did have a couple of contacts to the West-Coast US using the Loop – and got respectable reports back based on my 50W!

The Loop has  2 large lobes, and quite a deep, but fairly narrow null on each side.  The null is about 50-60 degrees and 2 S-points – or probably around the 12db  mark (give or take).  We did have a little bit of local noise, and rotating the loop we observed the noise drop right off to S1-2 when nulling the noise.

Side by side, with the Vertical – RX was on par, and TX was much better – just because there is a slight directivity associated with the loop .

Side by side with the Inverted V – well this was much more interesting – The Inverted V was only 8m high with each end about 2m off the ground.

The Inverted V was 2-3 S-points noisier than the Loop, but also 1 S-point stronger on the signals.  With an  S6 noise and  S9 Signal for the VK contacts, versus’s the loop, with an S3-4 noise and an S8 signal.

It clearly had at least 10db better signal to noise versus’s the Inverted V – and well, hands down beat the Vertical on TX!

The far stations reported slightly stronger signals on the Inverted V, but I don’t hold much faith in that as there was heavy QSB – I would call it a tie.

Conclusions

I would conclude that it is about on par with a dipole in typical performance – but has a considerably smaller footprint!  I was actually not expecting that the performance to be as close to the Dipole/Inverted V as it actually was – remarkable considering that you only need a very small space to have the equivalent of a rotatable dipole!

For the Amateur who is space-challenged or has a lot of noise, then yes, a loop is certainly worth considering for the low bands.

As we have the Loop for a couple more days, we will set it up in a typical urban lot – where we simply cannot use 40m as it is always S9+ noise  and make some observations as to how effective it is in a much noisier environment.

Remote Rx

Our previous JT-65 experiments came to an end when we needed the Antenna at our remote site for something new.

A few month’s ago, we jumped on-board with the KiwiSDR  and have been waiting for the project to come to fruition.

Kiwi SDR Kickstarter

Kiwi SDR Website

Other web SDR’s

So, after seeing a few Kickstarter updates and knowing that there were a handful of beta/test sites out there I decided to make contact with the Project Owner – John, ZL/KF6VO and put together a “proposal” to offer up the site as another beta test site.

Well, as luck would have it, John was happy to work with us for a couple of reasons – He had just 1 of the 10 boards left from his initial beta production run and he did not have a beta test site in VK.

After discussing details for a little while John sent the KiwiSDR and we have installed it onto the Gap Vertical Antenna in the Riverland.

Since it has been installed, we have found that the RX to be quite sensitive – quite surprising really!  The software is really quite easy to use as well.

It was a real eye-opener to “see” the whole 30Mhz of spectrum in the band scope display and realize just how much local noise there is at our site!

We know that there are still some software issues and within 24 hours of installation a further software bug was found and the auto-update rolled out the new version of software.

We are still waiting for a nice and quiet (rf-wise) linear power supply to arrive, and have it running with a fairly noisy switched-mode supply. As soon as we can this will get swapped out and hopefully improve things even more.

The Rx front-end is very sensitive to local noise – and we found that on power-up we had a very high noise floor.   We found that the noise was simply that the Ethernet cable crossed over the Antenna coax cable – and it introduced over 40db of noise, so some careful re-routing of cables was done and we saw massive improvements.

Yes,  there does need to be careful consideration of the installation and we could probably do a lot better than the simple protective case the SDR is in – we will probably put it into a decent metal case that is earthed to further reduce any local noise getting into the front-end in the near future.

Our previous experiments with JT65 had already proven to us the advantages to be had with running a remote RX site, and having the whole HF band available with the really simple and powerful interface has been great!

At the price-point, it is a great SDR – and much better than a simple panadaptor that only shows a single band – It is going to be one of those “Must Haves” for your Contest Station!

A little about the interface itself – Very easy to use – a simple point and click – select mode, select zoom on band display, enable/disable spectrum display, drag the audio passband – a continuously variable filter set the low and high cut frequencies to suit. Easy to adjust the Waterfall min and max sensitivity – once you set it for the band/noise floor it is really easy to “see” what is happening.

Whilst there is no noise filter, I have found that small adjustments to the audio passband can make a big difference.

There are now about 10 of the KiwiSDR’s around the world – so have a play  – you will probably go off and order one for yourself!  I will probably be getting a 2nd one after seeing how good this is!

… and just in case you have not already found it –

Have a listen on My KiwiSDR