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Wednesday, March 9, 2016

QRP and SDR: the best of ham radio

This has been observed so many times over the years: there are three distinctive 'opening' to Europe on 40m band around equinox.

The first one is via the long path which happens late afternoon, around 1 hour before Sydney sunset. The path is unpredictable- some days are better than others - but on a good day my QRP signal can be heard via long path in France, Germany and especially in Spain. The reason is simple: this is the early morning time in Europe, when noise level is low and Central/East European stations are already in daylight so QRM level is not an issue. While the signal path is 20,000+ km, almost entire path is over salt water and loss is minimal. Two-way DX QRP contact are possible thank to two positive effects: lack of interference and low loss. The window of opportunity lasts for 30 minutes or so. Unfortunately I arrive home from work late at night so this opening is often sadly missed.

The second and third openings are via short path. First of two occurs around 1am in the morning Sydney time when grey line is just hitting Easter Europe. At that time, Western Eu stations are still in daylight so Russian, Ukrainian and other Easter Eu's have clear advantage. Their QRM level is rather high (evening time) but mine is low (no plasma TVs!). The beauty of this opening is for the fact that my QRP signal is much stronger at gray-line that at any other time. This opening can last for two hours as the 'sun travels to the west' but rarely produces contacts with stations beyond Central Eu. There is just one problem with this great opening: sitting in front the radio at 2am local time causes serious marital QRM.

After 2am the 40m band gets very noisy. This is combined with another negative factor: finding a clear frequency is almost impossible since EU stations are everywhere- causing each other interference. A problem which they believe can only be 'solved' by running even more power. Slim chances for a QRP DX from down-under to break through.

The final 40m opening to Europe occurs in the early morning and peaks approximately 45 minutes after my sunrise. This opening is daily event and 'happens' all year around, summer or winter, but with various 'intensity'. Some days are better than others, and then some days are just amazing. However most of the time, the opening can be described as spotlight: the band conditions often favor a certain area. You work truck load of Italians on Monday and then bunch of Scandinavians on Tuesday, and HA/YO/S5 are strongest on Friday. You never know your luck- so planning a sked is impossible. And then again, no matter what the conditions are, I can expect to work at least one German station. DL's are everywhere and somehow, DL operators are keen listeners willing to answer even the weakest QRP CQ call.

Due to the nature of openings the best strategy for a QRP VK station is to find a clear frequency and call CQ in hope that someone will answer the call, spot you, which often results in a steady stream of callers.

Today, once again, the magic happened: I started calling CQ on JT9 mode right on my sunrise. I can see the EU signals getting stronger and then once again, bang-smack on 20:00 UTC DJ1TU answered my call for a an easy two-way contact. Yes the signals were just marginal, but the timing was perfect.

And when it comes to QRP DXing, timing is everything. You can have the best QRP SDR radio in the world, but if you don't know when and where to look for DX, then you will be wasting your time. Patience and persistence pays off. Quite frankly, any fool can run a pileup with 5KW and stack of yagi antennas and ham bands are full of them. Such activity requires no skills or expertise. But squeezing out that last dB out of your minimalistic setup and doing more with less is an art form. Nothing beats that magical experience when you work a station located on the other side of the world, when signals are barely audible, running just a few watts of power. And all of that with a radio you've built yourself, from scratch, soldering each component by hand.

73 happy solder smoke, happy CQing and see you on the air,

Nick VK2DX

PS there is one more reason I love SDR: there is no better way to maximize your investment in PC hardware than to turn your already obsolete, written-off machine into a two-way radio station! Your PC is loaded with millions of semiconductors you've paid for, so you may as well put them into a good use. SDR breaks barriers: there are still countries with large population which restricts / or make it difficult / expensive to import amateur radio transceivers. So what a better way to 'crush the oppression' but to build your own SDR hardware. Revolutionary, indeed!

DJ1TU JT9 qso, 40m band. GenesisRadio G40 @4W

A nice run of USA/JA on JT9 mode, local evening time. Unlike with Europeans, American and Japanese stations are 'easy' to work with low power.

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