Author Archive
I fancy some 472kHz WSPR!
June 26th, 2015 | 
Author: It is ages since I was active on 472kHz, so I might fire up the FT817 and transverter to see if anyone can spot my 5mW ERP or I can spot others. I shall use the earth-electrode “antenna” and go QRT on 6m to free up the FT817.
It is summertime, so noise levels will be higher, making my weak signal harder to copy than in the winter. It will take me about 5 minutes to swap bands and reset everything. The FT817 has to be set to 500mW and split mode so I receive directly on the 472kHz band but TX on the 80m band into the transverter.
If you copy me on 472kHz WSPR please report it.
UPDATE 2009z: Well, that was a good start! I just switched to MF and received 2 spots by G8HUH in IO81mg (250km) in daylight. I shall now leave 474.2kHz WSPR running overnight to see what else happens. With 5mW (maybe less) ERP I am quite happy with his -26/-27dB S/N reports.
UPDATE 2126z: So far G8HUH (250km) has spotted me 10 times this evening. I have spotted no-one and no-one else has spotted me, as yet.
Using the RTL-SDR as a transmitter
OK, this is very low power but it shows you what can be done. A QRPP transmitter or signal generator anywhere between 500MHz and 1.5GHz.
Please note the image below is not on my blog (it is linked as shown) and will be immediately removed if this is a problem.
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| http://rtlsdrblog.rtlsdrblog.netdna-cdn.com/wp-content/uploads/2015/06/transmit_hack_rtlsdr-500×375.jpg |
See http://www.rtl-sdr.com/using-the-rtl-sdr-as-a-transmitter/
10m – my best band of all
10m has always been my best band. I have lost count of the DXCC totals with QRP SSB. Chasing countries has never been a real activity of mine, although I still get a “kick” from working a new country.
At sunspot peaks it supports world-wide DX with QRP and simple wire antennas. Even in the quiet solar years there is often some DX to be found and usually late April to September there is sporadic-E (Es) to be found with good signals over ranges up to around 1500km and sometimes further. These are for the northern hemisphere. There tends to be a smaller Es peak around December/January. It is the reverse in the southern hemisphere. It is quite normal to hear USA stations by Es in the summertime, but usually openings are not for long.
If 10m is quiet it is worth checking CB frequencies (11m) as a “band open” sign. Often CB can be busy when 10m is quiet due to lack of activity. Thanks to Steve VE7SL for this good advice.
At night and in the quiet years it is an ideal band for local nets on FM or AM. At 1.7MHz wide it is big band so all modes can be supported.
See https://sites.google.com/site/g3xbmqrp3/hf/10m_op .
DXing with crystal sets
Yes, it is possible to hear a long way on a crystal set. The equipment needed can be extremely simple too. What is needed are a good pair of ears and sensitive headphones. My ears are getting old and if I can hear this DX then younger ears certainly can. I have found a low cost very high impedance crystal earpiece worked well. You may have better headphones?
Copying amateurs, most of whom use SSB, is more difficult. Remember, a simple crystal set is only able to envelope detect, although in the USA 75m AM signals are regularly copied at great range. Some SSB signals on 10m Es should be strong enough to envelope detect. Based on my tests, if stronger than 500uV to 1mV the signals should be copyable. Quite a few signals can be this strong.
Mizuho QRP SSB rigs
I don’t think this company still exists.
At one time you could buy Mizuho single band SSB handhelds for many bands up to 2m including many HF bands. I owned the 2m 200mW pep version (MX2) and managed to work some decent SSB DX with mine mostly with a 1/2wave whip on the rig. The main issue was the poor battery life, so I tended to use an external 9.6V battery.
My rig was used in the main with a homebrew 2m-10m transverter and I worked all over the world on 10m with just the tiny Mizuho rig on the desk.
If I remember right I covered the CW and main SSB parts of 10m by having a couple of crystals in the transverter. Somewhere I still have the transverter, although it has not been used for years.
Pye Telecom PF8
Some years ago I was professionally involved in the design of this innovative transceiver. I am sure I mentioned this on the blog not too long ago.
Some people managed to find rare examples on the secondhand market and converted them to 70cms use. They are hard to find as not that many were made.
VK3YE homebrew 7MHz SSB transceiver
Steve G1KQH (font, or is it fount (?) of all knowledge) sent me this link of the homebrew 7MHz SSB transceiver by VK3YE:
New Homebrew 7MHz QRP rig from VK3YE
