It was such a nice day

.. And I slept in and missed something else I had planned, so I went out and Played radio instead.

A quick look on sotawatch and noted a few people out and about, so a quick dash up to Mt Gawler – VK5/SE-013 after I had a great time yesterday.  Arrived around 01:00 UTC and just had a bit of a listen around the bands for a couple of hours,

Finally, saw a spot for VK3HRA on VK3/VT-013 and jumped on for a S2S contact.  At this point the charsers realized I was about to I moved up 5khz and put out a call to work a steady stream of takers over the next 30-40 minutes.  A lot of regular chasers in there and another S2S with VK1NAM on VK1/AC-027

Worked a few more – for a total of 25 contacts from VK1, VK2, VK3 and VK5 stations, most on 40M , but gave a quick call on 20M before leaving for the last couple of contacts who could not hear me on 40 before heading home for a late lunch.

When we got home, I turned on and had a quick listen around the bands – only to be confronted by my usual S9+ on 40M and S7-9 on 20M noise.  Yep, Mt Gawler, only 10km away is a whole different experience.

After Lunch, made the rash decision to shoot up to Mt Lofty – VK5/SE-005 to see if we could work a bit of Europe on 20M if it was open.

And work Europe we did! Found a clear frequency – as 20M was quite busy – put out a call and self-spotted.  For the next 40 minutes worked 29 EU stations.  There were a whole lot more but really had a hard time pulling callsigns out of the pile-up at times!  It was 0710 to 0748 UTC, which was the last hour before sunset here.

I didn’t log who, but I did have 1 station say that I was their First VK SOTA summit, quite a few saying that it was a new summit for them as well.

The noise started coming up and a couple of strong stations who could not hear me came up on the frequency, but given the sun was just starting to go down, I called it quits on 20M and dropped the dipole and unwound it for 40M and pushed it back up.

Again, a single spot and a 10 minute mad dash on 40M and had another 13  calls from VK1,2,3 and 5’s in the log.

A quiet RF environment for RX, a 10W Radio and calling CQ sota when EU is open – Fun!  Today was the first day that I have really used the KX3 – and Yes, it is a great little radio for taking portable – a great RX and very easy to operate all-band, it might just be the perfect portable 🙂

Given that the days are starting to get longer, and Mt Gawler is a lot closer for me to get to, I can see me jumping up there maybe on a few week days and calling on 20M as well and seeing how that goes.

VK5/SE-013 is not Mt Nigel!

This morning, decided to give the New KX3 a go – given that I had finally got everything all together!

Should have taken a couple of photos, but hey, too busy working everyone today!

Of course, Mt GAWLER being only a 15 minute drive and a decent quiet HF location compared to home, it is my “go-to” location for portable operations.

Finally managed to get together my new lightweight 40M dipole wound up on some new winders cut from corro board.  So, with 1/2 of each dipole un-wound, a quick check on 20M and it was tuned pretty close – bumped the ATU and it locked right in.

Gave a call for about 15 minutes, but no replies, so switched over to 40M at 2341 and made a call – only to be flat out until the day rolled over – when I was smashed!

The KX3 Rx is very nice! was able to hear just about everyone today, possibly only missed 1 or 2 who were calling who were right down in the noise.

What was good today, was a couple of S2S contacts – 1 before and another after UTC roll-over, both not the best conditions, but glad to be able to complete and log them both.

With 23 Contacts before UTC and a further 29 after roll-over, it was a very busy time for about 40 minutes!

And for all the chasers who tried to tell me that this summit has now been named Mt Nigel, well, keep an eye on the spots – this sounds like a challenge to me 🙂  With the days starting to get longer, Chasers better keep an eye out, I might just head out on weekday evenings so we can re-name this Hill to Mt Bob!

I won’t list all the contacts, just the Prefixes:

VK1, VK2, VK3, VK5, VK6 and VK7 stations were all worked today, logs are all uploaded, so chaser’s the points should validate once you upload your logs.

VK5/SE-013 is Mt Gawler, or It can also be called Mt Bob, but NOT Mt Nigel 🙂

for something completely different

This morning had an interesting email that led to a pretty interesting day!

The email was from VK3YT saying that a pico balloon he had launced earlier in the week was coming down near our remote digi (vk5thb-1)

We had a few things that we should have been doing, thought about it for about 30 seconds and loaded up all sorts of gear into the car – we were going balloon chasing!


Andy sent the above image taken from the spacenear website  showing the track of the balloon and the predicted landing site along with the frequencies that the telemetry and timings etc were being sent by the payload.

We headed out and made our way to the predicted landing site as per the above image and waited around for 3 expected telemetry transmissions but heard nothing.

So, made our way back to the highway, closer to the last transmission point, again we heard nothing, so finally moved again.





We moved just north of the highway – and drove along a non-existent track, to near the “Red Dot” and finally managed to hear some telemetry on UHF.  We only partially decoded it and only got the Long – and not the Lat – so we were 1/2 way there.  But we  were also able to DF the signal and get a direction! Using a YNG sniffer and a 5 ele Yagi, not strong -but with the signal only being 10mw it was hopeful.


So we waited again and did not get a signal – the batteries were getting weak and the time between signals was increasing!


We moved, based on the direction of the DF’d signal and heard it at an S5 near the Red Mark, but didn’t decode the signal at all.

Given we had a strong signal at this point, we stopped the car, and just waited, and waited and waited.  Finally 30 minutes later, we got a signal, decoded the telemetry with the GPS co-ords in it.


We took a screen shot of the decoded Oliva 8-250 Telemetry we received on UHF – The IC-7100 in the car meant simply plugging the laptop into the radio and have the appropriate software loaded.

We punched the details into the GPS in the car, and drove to within 400M – the closest point we could get to.

We could see a silver thing on a fence and thought that it must be the balloon. So, grabbed a handheld with a GPS/APRS in in and started walking.  Sure enough, it WAS the balloon!

And I had actually spotted this on our first pass up the road on the way to the original predicted landing site and commented that maybe that was the balloon (approx 2 hours earlier).


Above photo was of the balloon on the fence, you can just see the string heading down to the payload.  The treeline in the background is the approx 500M  back to the road where we could drive to.


The balloon, looking along the string to the payload – which is there in the wet grass!


A zoom of the above photo – follow the string, you can just see the final resting place – You can just make out the yellow covering of the payload  and 1 of the Solar cells.


The actual payload, once I had moved it so I could see it!

The reality is, given that the final resting place was in wet grass, yes it was raining! and given that the antenna was entirely at ground level -we were pretty lucky to hear anything at all!

The first signals we got from it were around 3km away and very weak.  The final signals were from about 2km directly across an open paddock!

Well, Andy, this is one that got away and is going to come home!

Look at the details of the flight of PS-16.

It was a fun afternoon to assist another Amateur with the recovery of their experiment and will follow further launches.


Impromptu activation

With Winter well and truly here in South Aus, it puts a little bit of a dent on going out and activating!  It has been raining almost every day this week, but a break in the rain today I made a quick decision to grab my portable kit and do the 20 minute drive up to Mt Gawler – VK5/SE-013

This is not only a close to home summit, but an easy activation, given that Most of Mt Gawler road between Airstrip Rd and Millbrook Rd is in the activation zone.  We drove in, parked the car, grabbed the bag with the gear and walked out of the activation zone down the trail into the Mt Gawler Reserve, then back up.

On-air and calling it took a few minutes before the first contact for the day, as there was a lot of noise on the bands and RTTY way down almost everywhere!  We were on the “protected side of the hill, but it was still windy and cold.

We had a steady stream over the next 30 minutes and packed up about 45 minutes after arriving having 21 contacts logged, and unfortunately a few missed ones today.  A few reports of my signal being a bit off today means I need to take a quick look at everything, possibly due to the cold and not a fully charged battery could have contributed.

No points for me as an activator this time, but the chasers appreciated the 2 points from this summit, and it is good to have an accessible summit that I can get out away from the noise at home at very little notice.

Today, managed to log VK1, VK2, VK3 and VK5 stations, quite a few of now familiar calls and a few new ones as well.


Timed it perfectly today as 5 minutes after leaving, the rain started yet again.

Putting the KN-Q7A thru it’s paces

Last night, had the opportunity to sit down with some test gear and run the KN-Q7A 40M txcvr thru it ‘s paces.   At the moment, the only modification from stock that I have done is to replace T3 toroid in the output stage.

Having access to a 2-tone generator, calibrated signal source and spectrum analyzer, power meter and dummy load was what we used for the testing.

Silly me, did not get any screen-shots of the output.

Basically, we did a 2-tone test, minimal discernible signal, IF bandwidth, spurious output.

2-tone test

Adjusted the level of the tones until the output power peaked – and it peaked right at the 13W mark.  We left it key-down into a dummy load for around 10-15 minutes – which is far more brutal than any real-world use will ever be!  The Final did of course warm up a bit- was certainly warm but not so hot that you could not touch it with your finger.  The whole case (heatsink) did increase in temperature, showing that the design is quite adequate.

We took a look and found that the output was not that clean!  It took a little bit of trimming of the BFO to improve things, and once sorted out, it looked like the IMD at it’s worst – which was when we dropped the input level so that the output power was around the 10W mark.  It was at about -23db.  While not brilliant, nowhere near as bad as what others have reported.

The odd thing was that there is a very “sweet spot” when it was driven pretty hard and at full output power, we saw the IMD drop right down to around -30db!  Yes, at full output power, the signal was a lot cleaner than at all lower levels.  The Worst case was in fact -mid-power – right in the area where normal voice would be.

This pretty much confirms that I need to go ahead and build a compressor before feeding the audio into the 602 Mixer – a mod I had actually planned on doing.

Minimum discernible signal

We used a reference level signal generator and set it to about 7.090, tuned the rx to it. Then it was simply a case  of tweaking the RX until the tone was mid-range in the bandpass filter then lowering the level. Surprisingly good is what I would say here!  a CW tone was easily heard way down at around -124dbm!  beyond here it was noticeable for another 2db, but all gone and nothing heard at all at -127dbm.

Lets look at -124dbm – that is 0.14uV and that makes it a pretty hot RX!  My “gut feel”  that it was a good rx was totally confirmed.

But let’s not get ahead of ourselves – this was a single-tone test and listening by ear, so lets be a bit realistic and add 10db to that single tone figure  and at -116dbm = 0.35uV

IF bandwidth

Pumping in a CW signal at 7.095, at -90dbm level then tuned the RX to it.  Then by listening to the output, the signal was varied up/down in 100hz steps.  It was dead easy to show that the B/W if the IF Xtal filter is as I had already determined is 1.8khz wide, with a very clean, response with a slight roll-off at the 100hz mark on each side.  I wish that my other commercial gear was as good to tell the truth!

-90db signal level gave us 35db over the minimal level, so that all we can say is that at 1.8khz, the filter is better than 35db.  Didn’t think to try this at a higher level to determine how steep and sharp the filter is, but in the real world it is certainly good!

Spurious output

Well this is where it got a little interesting – and yes there were a few bumps along the way.

First off, the 2nd, 3rd, 4th and 5th order harmonic outputs.

2nd was at about -63db, 3rd was at -68db, 4th was at -72db and 5th was at -80db.  Could not determine if there was any higher orders as they were in the noise floor.  Given that on 40M the 2nd, 3rd and 4th fall into other Amateur bands, this is not going to cause any interference – especially when you look at the levels!  -63db with a 13W output is way down at 7 micro watts!

Now the VFO/BFO products. this is where things were not quite as clean!  There were 3 obvious products – 1.3Meg, 5.8Meg and 8.4Meg. If you look at the IF frequency then these all make sense!

It is output + and – the IF difference – 8.467 – 7.1 = 1.3Meg (approx), and then 7.1 + and – the 1.3Meg

If = 8.467Mhz, VFO = 15.570Mhz (+2khz, – 35khz)

The 2 that were +- 1.3Meg from the signal were around the -45db mark and the one at 1.3Meg was down a little more – at about -48db.  Rather than a simple low-pass filter on the output, a better band-pass filter that is reasonably tight would be needed to knock these unwanted products down a bit more.

Measured v’s Spec’s

Finally, lets pull the “specs” and compare them to what we actually measured!

My kit was the Mar 2014 Rev D PCB V2.2 with the IRF530 FET as the final.

  • RF output: about 10 W PEP @ 13.8 V
  • Spur suppression: better than -43 dBc
  • Sensitivity: better than 0.5 μV at 10 dB SNR
  • IF bandwidth: about 2.0 kHz

What we measured

  • RF output:  13W PEP @ 13.8 V
  • Spur emission: -45 dBc
  • Sensitivity: 0.35 μV at 10 dB SNR
  • IF bandwidth: 1.8 kHz

Now, in all of this testing, the only adjustment that was made was the BFO trimmer, all other tuning was left as it was from my initial tuning.  Truth be known, a little bit of tweaking could have possibly seen some further improvements, but that was not the point – it was to look at what was going on by doing nothing more than following the tuning steps – which is exactly what anyone building the kit would have done.

Lets face it, all in all, for a transceiver that costs only a bit over $100, this is really quite impressive!

Yes, doing these measurements  and now having something to go on shows me that this design if advanced just a little more could move it from pretty good to excellent!

From a pure usability perspective, adding a “tune button”  – resistor to gnd + bypass cap on the NE602 to un-balance it and give around 2W out would be nicer than having to do the whole whistle/tune thingy!

Adding the compressor stage and and AGC to improve both TX and RX experience and finally, a little more output filtering would take this from a good to a great transceiver.

Now, I am going to get on and build the DDS to give me a tad more band coverage, built an audio compressor stage, another Audio out stage with AGC myself over the coming weeks, that is of course, between getting lots of use out of this little rig!