Elecraft KX3 internal photos

Elecraft KX3 rear view inside

Lots of QRP operators are eagerly awaiting the release of the KX3 from Elecraft early in 2012. This is a very compact all mode 10W rig suitable for home or field use. It was first lauched back in May 2011 and Elecraft have been busy completing the design and doing field tests. I came across some internal photos on VA3KV's site that I'd not seen before which give some idea of the design. It can be fitted with internal batteries and an internal wide range auto-ATU making it a very versatile transceiver packed with features. Spec is expected to be excellent and not far off that of the K3.

481THz progress update

TX beacon optics

This morning I bought a length of 110mm waste pipe from the local Plumb Centre shop. It came in a 3m length and only just fitted in the car to get it home! After lunch I created my first attempt at some optics inserting my Poundland 100mm lens into the end of a cut section of the pipe. At the focal length I mounted my 10 pence high brightness, prefocussed, LED beacon with Bluetac. With this (crude) set-up on an old tripod and with a taped on gun-sight to help with aim, I set the TX baseband beacon running and pointed it from the stairway through a double glazed window aiming down the road. With my handheld baseband head using just the high brightness 10p LED as the detector I walked down the road to see how far I could get. In the beam in daylight I could detect the signal at the receiver at 120m. With a magnifying glass in front of the RX LED signals at 200m were strong (could not test at greater range), but it was difficult to keep the RX aligned. The red LED was quite strong visibly at the 200m test point even though running just 15mA or so through it. The double glazed window no doubt added a small amount of attenuation. What I'm not sure about is how good (or bad) this result is. Clearly with a really high brightness Golden Dragon LED the range even with this system would be considerably further.

LF tests with the earth electrode "antenna"

Following the great success on 160m with the 20m spaced earth electrodes yesterday, I fired up the WSPR transverter into the same "antenna" today on 137.5kHz. Although I managed to decode G8IMR at 188km several times, no reports of my signal were received. This ties up with tests last year which suggested the earth electrode system was around 8dB down on my 80sq m vertical wire loop. With results on 137.5kHz hard to get with 500uW ERP it was perhaps not surprising that no-one managed to decode me on the earth electrodes.

I now have a choice on 137kHz: either re-erect the wire loop, but double the wire thickness when I do so, or change to a Marconi vertical with a large loading coil. The thicker loop will increase ERP by up to 6dB but I suspect more is to be had with the vertical. It would be daft of me not to give the Marconi a try both on 137.5kHz and on 500kHz. Even with my limited space I can still manage around 8m of vertical with around 20m of top section.

Amazing evening on 160m ...without an antenna

160m WSPR reports - using 5W to 20m spaced earth electrodes

What an amazing evening: tonight I let my 5W WSPR beacon run with my VLF earth electrodes (20m separation with a low wire feed) as the "antenna" i.e. no conventional antenna in the air at all. Just look at these results! 6 countries and best DX 896km to the Shetland Is. If the earth electrodes are acting as a "loop in the ground" then the Shetlands are in the wrong direction i.e. in the null of the loop.

Sunday I intend to try 137kHz with the earth electrodes as I now have some 6dB more power than the last time this was attempted.

Earth electrode "antenna" on HF

Today I had to prune the tree to which my 80m sq wire loop is attached, so the loop had to come down for a while. Instead I connected up my 20m spaced earth electrode pair "antenna" with the connecting wire about 1.5m off the ground coming back along the garden fence. This is the antenna I use on VLF earth mode tests with the best DX reception of my signal being 6km away when using 5W at 8.76kHz.

I have been amazed how well this works on 160-40m this afternoon. This is the log this evening on 160m with 5W WSPR - best DX report so far from OZ7IT at 853km. On 40m I reached over 2000km with a report from the north of Norway.

10m - still WIDE open

A small wire halo antenna, 5W from an FT817 and WSPR software and these are the loggings of my 28MHz QRP signal in just a few minutes this morning. Best DX report 16964km from VK2ALC.

481THz (light communication) progress

This afternoon I did a bit more on the optical front. I repeated my outdoor range tests using a low-cost high brightness LED as both a baseband optical transmitter and receive detector. With around 10mA TX current into the LED I was able to copy a 1kHz tone at 20m with another high brightness LED as the detector, without any additional optics other than the LED's built-in lenses at each end.

A 100mm lens properly focussed has a gain of >24dB (nearer 30dB if correctly adjusted). Assume 24dB "antenna" gain at each end of the link and we will have 48dB system gain over the simple LEDs on their own. Based on these calculations my optical transceiver should have a range of at least 5km.  If the gain of the lens is 30dB then the range could be as great as 20km. This is without using high power LEDs as the TX or using larger Fresnel lenses which would have even higher gain.

I now have the 100mm lenses I intend to use as well as 2 gun sights bought off eBay. The next step is to buy some drain pipe to house the optics. I have still to decide whether to build fully self-contained FM transceivers (simpler) or to build the optical transceive heads with separate transverters to use with the FT817.

RF skill levels

In my professional life I interviewed many graduates aspiring to become RF engineers. Very few, in recent years, had what I would call "the knowledge". By this I mean a "gut instinct" for RF that does not come from an academic course, important though this aspect is.  Rather, this "jizz" comes by living and breathing RF through building RF things yourself, however simple. A great many 2:1 graduates in communications electronics knew almost nothing about RF, had never touched a soldering iron ever and were rejected. In all honesty I believe I could sense who would make a good RF engineer within 2 minutes of the interviews starting.

Today I received a request from a Spanish amateur who professed (more or less), "I`ve a problem. I know nothing about electronics and would be unable to build the SAQ converter on your website." He then offered to pay me to build and ship the converter to him. Surely, a radio amateur in ANY country should have learnt basic RF skills as part of his training in preparation for his licence? At the most basic level the understanding may not be deep, but how can a radio amateur really not know how to put together a basic circuit?

In the UK we have a growing, and very serious, issue with poorly educated science and engineering graduates who are simply not coming out of universities with the skills needed to start work in industry. One answer was the sandwich course in which young A-level students were accepted on a company training scheme that married "on the job" skills training with educational training, usually to HND or degree level. People spotted young, with real RF "jizz" (easily judged in interviews) usually went on to become the best engineers we had.

Sunspot peak to be over 100?

The latest NOAA sunspot predictions show cycle 24 now peaking in May 2013 at a smoothed sunspot high of exactly 100. This is UP on earlier forecasts and the actual trend since this forecast was made is still upwards, I believe at a rate faster than NOAA was predicting.

So, despite the gloomy predictions of even 6 months ago, we seem to be enjoying a decent solar cycle after all with every prospect it will be better than even current forecasts suggest. Whatever, conditions on HF will continue to be good for 5 years to come, so go and enjoy them.

Today my QRP WSPR was copied in Australia a couple of times on 10m yet again. It appears that every time I fire up it gets >16000km. I just wish a few more East Coast USA stations would  come onto 6m WSPR as this is where the excitement will be for the next  few weeks if F2 MUF reaches 50.293MHz.

Busy amateur VLF weekend

G3ZJO's reception of DK7FC on 8.97kHz

Yesterday's test by DK7FC from his fixed location was a resounding success with reception all over Europe by many stations including G3ZJO, G3WCD and G3KEV, and what is believed to be the first transatlantic reception of an amateur VLF signal by a station in the Eastern USA. Results are being checked as I write.

Stefan's ERP was later re-calculated as around 800uW. It is incredible that such a tiny VLF signal can be detected so far away. If confirmed, this certainly heralds the dawn of a new and exciting phase of VLF amateur work. With another 3-6dB ERP, worldwide amateur VLF DX is now a real possibility. Of course such VLF DX reception requires incredible frequency stability, very narrow RX filters and long signal integration times; signals are far too weak to hear.

Also, Marcus DF6NM ran a 8.97kHz test today using a kite antenna. G3ZJO received a good signal in IO92ng 20dB above the noise in 424uHz bandwidth. Marcus was also well received by many other stations across Europe.

In summary, this weekend has been a BUSY one on the Dreamer's Band.