Simplest possible SDR transceiver?

A challenge - what is the simplest possible SDR transceiver that can be built that would allow credible results on HF QRP? Does anyone know of any links to such ideas? Is there an "SDR equivalent" to the Pixie or similar ultra-simple QRP rigs, possibly supporting all modes but using just a handful of parts?

Software Defined Radio (SDR) kits

Received this today about SDR kits from Australia:

Hi Roger -

Here is a piece of information that may be of interest to your blog readers / website visitors: our little SDR KIT project is gaining momentum - we've been in business for less than one month yet we now have builders in 14 countries. See http://www.genesisradio.com.au/G40/ . We also have 2 new models coming out very soon: 20m and 30m duobander and single 80m SDR transceiver.

Thanks for reading.

Best 73
Nick VK1AA

Anyone built the Gnat-1 micro-transceiver?

Has anyone reading this blog built the neat little GNAT-1 transceiver featured in SPRAT 138 (Spring 2009) by Chris Trask N7ZWY? This looks a very elegant design making good use of the small number of parts needed. I must have a go. Unlike the FETer and similar micro-transceivers it doesn't need complex switching and it produces a decent RF output.

Chris tells me he hasn't actually air-tested the circuit (surprisingly), so I'd like to hear how people get on. It is important to keep the key leads short Chris advises.

Hurrah - a sunspot!!!

Solar flux reaching the giddy heights of 71.0 and today there is 1 sunspot on the visible side of the sun. Things may be looking up after an absence of spots for 2 months.....

Next day it had gone :-(

10m activity (of sorts)

Just checked 10m for signs of sporadic-E but only heard a UK station M0CHK who appeared to be testing his rig audio with another unidentified station. Signal was weak with me.

20m AM

IK6BGJ was a good signal this afternoon on 20m AM on 14.251MHz. Although he called CQ AM many times he did not work anyone and was unable to hear my QRP reply when running 4W AM. Pity - it is a very long time since I've worked anyone on AM on 20m. 1967 to be precise!

70ms QRP FM simplex

QSOs this afternoon with G4BFS/M and M3VDO/M on 433.5 FM - local mobile stations running QRP at all ends. No great DX (best about 20kms), but nice to work some stations on the band mid afternoon.

70cms lift conditions today

Conditions on 70cms were good this morning: at breakfast time (around 0700z) several more distant repeaters were coming in at good strength here in East Cambridgeshire. Amongst them was the Leicester repeater GB3LE which was fully quieting here and easily accessible with about 2W ERP. I called and said I was listening on 433.5 for simplex QSOs, but there was no-one about. 70cms has frequent localised openings which appear for a few hours then disappear, It is a great pity there is not more simplex FM on 70cms as it is good fun working DX with QRP using this mode with simple colinear antennas or even handhelds.

HF broadcast band reception

With the broadcasters supposedly moving out of the 7.1-7.2 MHz slot from earlier this month I thought I'd check who was still there last night. Firstly Radio Ethiopia on 7.11 was a strong signal as was Voice of Broad Masses of Eritrea on 7.175MHz, both around 1915z last night. Also heard on 7.570MHz was Radio Thailand. I guess this is in the new 41m band allocation?

At much the same time a listen on 15.120MHz brought in Radio Nigeria at good strength at 1930z with their news commentary in English.

All this BC listening made me quite nostalgic for those heady days in the 1960s when the joys of Radio Sofia, Radio Prague International, Radio Moscow and others graced the airwaves with their propaganda. Although I never cared for the propaganda I did like the interval signals which thrilled me when receiving them on a crystal set under the bed clothes late at night. Hear these again at http://www.intervalsignals.net/ .

A useful guide to English language BC schedules and frequencies can be found at http://www.primetimeshortwave.com/ .

The VERY quiet Sun

Have you noticed how long we've been now without any sunspots? The graph at http://www.solen.info/solar/ suggests it's been almost 7 weeks now. A few months ago we were expecting the start of cycle 24 and some hopeful signs were emerging. Then things turned down again and it is doubtful we've started to enter cycle 24, although the slightly increased solar flux levels may be a hint. We can only wait and see.

At least the higher HF bands plus 6 and 4m will be livened up by sporadic-E shortly. If we were entering a long Maunder minimum (I doubt it) then the summer spor-E "sport" could be the best DX opportunities we'd get on 10 and 6m.