40m Pixie: a tip I was given

Andy Cutland in the Channel Islands has reminded me that it is well worth checking the Reverse Beacon Network to see if the signal from the Pixie is getting out, even if no replies are received. I must admit I've not yet been doing this. From now on I'll check the RBN although I usually reply to CQs rather than call CQ when using QRP (search and pounce).

Sunspots and 10m - Monday March 2nd 2015

Yesterday was dire(ish) on 10m.   Let us hope today is better.   My 500mW 10m WSPR beacon has been on for 20 minutes, but only being spotted l.ocally so far.

Sunspot number today is 66 (not bad) and 10m propagation is expected to be "fair".

UPDATE 1000z:   I see 4X1RF (3519km) has spotted me.
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UPDATE 1130z:   4X1RF has spotted my 500mW 10m WSPR beacon 4 times so far this morning. He is, so far, the only DX station to copy me.  It seems pretty quiet.    

UPDATE 1212z:   4X1RF has now spotted me 5 times today so far. No other DX spots received today.

UPDATE 1410z:   4X1RF has now spotted me 8 times today so far.  Still no transatlantic spots received though. I am beginning to think the long afternoon openings on 10m to the USA are ending.

10GHz WBFM transceivers

The modern way of getting (simply) into 10GHz WBFM appears to be using very low cost 10GHz Doppler radar modules with a 100MHz FM receiver. Whilst with G6ALB for my Pixie tests Andrew demonstrated a working 10GHz link based on these low cost modules. These are useful links Andrew sent me.

Hi Roger,

These are the units I found when I was looking for [definitions of] the 10.525 GHz ISM band.

http://www.ebay.co.uk/itm/231418556511

It looks like 3cm Doppler radar is alive and well,I’d assumed it had disappeared in favour of PIR.

https://www.youtube.com/watch?v=qkb-IIYq-Dg

Some data here:

http://www.limpkin.fr/public/HB100/HB100_Microwave_Sensor_Module_Datasheet.pdf

http://www.limpkin.fr/public/HB100/HB100_Microwave_Sensor_Application_Note.pdf

These are very good pages (for wideband FM on 10 GHz).

http://www.g3pho.free-online.co.uk/microwaves/fs1.htm

http://www.g3pho.free-online.co.uk/microwaves/wideband.htm

 Andrew G6ALB

40m Pixie measurements

Pixie harmonic measurements

This afternoon I visited G6ALB to do some more accurate measurements of my completed 40m Pixie kit. Power out with the 12V battery was 400mW and with a fresh PP3 9V battery 200mW. On the 12V battery TX current is around 129mA and at 9V around 83mA. 2nd harmonic rejection was about 20dB. Even the 9V output is a useful level. Maybe the cased unit should include an internal 9V battery pack which is switched off when an external 12V pack is available?

Pixie on the bench

To be more useful, I should add a 7.030MHz crystal and have a switch to select this or the original 7.023MHz one. 7.030MHz is the QRP frequency. My experience is this can be quite busy.

I should also case the unit!  Drilling the case could be a challenge in my current state of health! Just doing the building and testing was exhausting.

USA 10m WSPR spots (or lack of them!)

It is now 1330z and so far not a single USA station has, yet, spotted my 500mW WSPR beacon. OK , it is still quite early and things may well be better later, but yesterday was far better on 10m. Plenty of reports from Eastern Europe and near Asia though.

So far, 10m has been a bit disappointing today.

UPDATE 1445z:  And still no 10m WSPR spots from the USA today yet!

UPDATE 1448z:  In the meantime, 4X1RF (3519km) has spotted me 22 times so far today.

On 472kHz no-one had copied my 5mW ERP so far until this afternoon when G3YAC (12km) and G8LCO (58km) copied me. My best DX on 472kHz WSPR receive is PA0A (417km) who has been coming though during the day.

UPDATE 1530z:  I have the feeling that I'm not going to have my 500mW 10m WSPR beacon spotted in the USA today. If the band does "wake up", I suspect just a handful of USA stations may be lucky.  By now I'd have expected some transatlantic spots. That is the nature of 10m: you can never be sure. No wonder some call it a magic band.

UPDATE 2048z:  So, the day passed and not a single USA station spotted my 10m 500mW WSPR beacon today.  Conditions are on the change?

Sunspots and 10m - March 1st 2015

Sunspot number has climbed again to 70 and 10m propagation is forecast to  be "fair".

So far this morning reports of my 10m 500mW WSPR beacon from G4IKZ (18km), G4KPX (14km) and 4X1RF (3519km). I had to remove the antenna and turn off the beacon for a period to use the antenna on 40m CW.

First 40m Pixie QSO

At 1000z this morning I exchanged RST 579 reports with G6ALB who is 3km from me on my 40m Pixie on 7.023MHz CW. This was my first on-air QSO. Netting was perfect and I used the rig directly into my low Par triband antenna. An ATU might have helped. Andrew G6ALB said the channel was pretty busy but that I was a good RST579 with no hint of chirp. This afternoon we'll put the rig on his spectrum analyser. I gave Andrew 579 probably reflecting the poorer MDS of the Pixie. I have no idea of his power or antenna.

My initial goals have been met: I built the kit and have managed a QSO on the air with it. With the fatigue associated with my brain bleed still very apparent (I am well and truly shattered currently), I was well pleased. A few more QSOs with the 40m Pixie would be good, HI.

$10 well spent. Excellent little kit. FB little transceiver. Works surprisingly well.

40m Pixie - bench test went well

Well, it took a super-human effort on my part as a result of my extreme fatigue (brain bleed issue) but today I bench tested the little 40m Pixie kit I managed to build earlier this week. It is hard to explain just how exhausting this simple task was for me currently. I now need to recover my energy!

On receive a 1uV signal was perfectly readable and I could detect carrier on/off down to at least below 0.5uV. On TX it was putting out about 250mW into a 50 ohm load. On my antenna it was suffering some AM breakthrough, but less than I was expecting. I was using standard Walkman stereo headphones and a rechargeable 12V sealed lead acid battery. On a small 9V battery I'd expect about 100mW RF out, although this was not tried.

Overall, these results exceeded my expectations: it is more sensitive than I was expecting and the breakthrough of AM broadcasters is certainly OK in the day time. This is of course with no casing at all and no ATU. Using the fitted pot and fitted 1N4001 as a varicap it is easy to get the TX frequency and RX frequency to correspond, often an issue with very simple QRP rigs.

Next stage will be some on-air tests, but it most definitely works. Working the locals should certainly be possible. Sked with G6ALB (3km) arranged for 1000z Sunday on 7.023MHz CW.

UPDATE 2120z:  There is a contest in full swing and several Russians and Asiatic Russians copied on the little 40m Pixie. I did not stay on long but there was no apparent BC interference noticeable. So, on a quiet night I should able to use the rig in the evenings. The main issue on RX seems to be the lack of AF filtering, so one has to use "the filter that is between the ears" i.e.the brain.

Amateur Radio Weekly

Yesterday I subscribed to this online newsletter. It is also available every Saturday on www.amateurradio.com

One of the items was about Deutche Welle (German broadcaster) vacating a slot in the 49m band. A group of radio amateurs have obtained permission to use a 10kW commercial station there. This is their website http://www.channel292.de/ . Best of luck to them!

10m USA spots today

KZ8C (6290km) was the first North American to spot my 500mW 10m WSPR today at 1248z. Since then, K9AN (6505km) has also spotted me several times. I think he has a very good RX set-up as he is often copying me on 10m.

I have the feeling there will be a lot of 10m spots today as conditions seem quite good and it is the weekend.

UPDATE 2035z:   The last USA station to spot me today on 10m WSPR was KB9AMG (6300km) at 1922z. Quite a decently long opening today.