G4EFE WSPR with 5 mW on 40 m

Martin G4EFE is an enthusiast milliwatt WSPRer.
I curiously follow the WSPR adventures of Martin in which he uses very low power.
Here I show new analysis of the spots that Martin made with a power of 5 milliwatt on 40 m with a full-size 40 m square loop.

The table shows the number of spots over a three day period, from day to day and hour to hour.
From the used power of 5 mW (in all spots) and the SNR, I calculated the lowest possible power.
A spot with a SNR of -28 dB is a "solid copy" in WSPR. So when, for instance, the SNR is -18 dB, the signal is 10 dB stronger and could have been 10 dB lower and still give a solid copy, with a SNR of -28 dB.

The better the SNR, the stronger the signal and the
lower the calculated lowest possible power will be.

Propagation
In the spots that were received by F6EHP, you can see the development of the propagation from hour  to hour. You can see that the signal peaks at 9 UTC at 3-2-2017. The strongest spot could be made with a power of 0.1 milliwatt. This is also the strongest spot in this table.

Martin uses his IC703 and an attenuator to make a power of 5 milliwatt. His antenna is a full-size 40 m square loop. As I saw on WSPRnet.

G4EFE WSPR with 5 mW on 40 m

WSPR is a beacon system that is designed for low power. How low can you go?
Martin G4EFE ran WSPR with very low power.

Martin G4EFE wrote after experimenting with 1 mW, using his attenuator of and 20 dB:
So I've had a little time for some experimentation, and the results - I think - are spectacular. Attenuating the output to just 1mW netted me several spots from neighboring countries. 
Best DX was GM* at 711km, who reports me at -18b dB SNR, suggesting I can go even lower.
So today I'm running just 100 MICROWATTS. I can't believe anyone will spot me, but I'm the optimistic kind! Thanks again, Bert, for this easy and fun station accessory. 

The map, the tabel for 1mW and the picture of the beautiful attenuator can be found here: https://www.flickr.com/photos/71155570@N00/albums/72157679958156316
OK Martin, thank you for sharing this fine info.

5 mW down to 1 mW
Martin started with 5 milliwatt for three days, as you can see in both tables. On the 5th the power was reduced to 2 milliwatt. On the 6th Martin had great fun in 21 spots with just 1 milliwatt.
To make a power of 1 milliwatt Martin uses his IC703, at it's lowest setting with 100 mW and an attenuator of 20 dB. His antenna is a full-size 40 m square loop. As I saw on WSPRnet.

From hour to hour
In the table below you can see the number of spots in each hour.
The days go from the bottom to the top.
The number of spots vary from day to day. this is not only propagation.
Martin is constantly transmitting, but the listeners can be jumping from band to band.

G4EFE WSPR with 5 mW down to 1 mW - From hour to hour

The best DX from GM*with a SNR of -18 dB, that Martin refers to, gives a calculated lowest possible power of 0.1 milliwatt. This spot could be made with 0.1 mW and still be a solid copy with a SNR of -28 dB. See the spot in the red circle in the table below.

G4EFE WSPR with 5 mW to 1 mW, using an attenuator

The better the propagation, the better the SNR will be and the lower the Calculated lowest possible power. The Calculated lowest possible power is calculated from the power and the SNR.

Stefano IZ1OQU makes SSB QSO's with 5 mW

Stefano IZ1OQU 5 mW SSB
with light weight VHFantenne

Hi Bert,

One year passed since our last email and now I write to tell you some recent news about my experiences with power attenuators in QRPp.
Last Sunday, during the Italian Apulia Contest VHF on 2 meters, I made 19 QSO's.
11 QSO's were completed with 5 mW, 4 with 50 mW and 4 with 500 mW. 

I never needed to repeat my callsign. No propagation, no e-sporadic: just directs. 

The best QSO was with a French station over 312 km, good for 62.400 kms per watt. 

My operating location was 500 m asl, with good opening to the sea and the French coast. I'm forgetting to say... That it was SSB!

The antenna is a personal design, low weight very easy to use on portable: two rectangles vertically linked to each other, with nice gain and good front/side. You can see it on my qrz.com. But I attach a photo for your comfort.

What an unbelievable experience! The first time with 5 mW drove me crazy. Surely VHF offers big chances to play with micro-powers, thank to big-gain antennas both on tx and rx sides, and global low power absorption. It is a test that I want to repeat as soon as possible, looking for DX.

Every time I think back to the day that I found your website: my life changed and my passion for QRPp now flies on golden wings. Thank you again, my friend.

Best regards

'73 de IZ1OQU Stefano

Peters QSO's with 5 milliwatt

Are you curious how Peter DL3PB made these amazing QSO's, with an 

All diode transceiver with just 5 milliwatts on 15 meter, then read this
informative e-mail from that I received from Peter.

Hello Bert,

Glad to hear from you and thank you very much for posting my latest milliwatt results on your blog and the kind comment - I like especially the stamp-sized logos for each entry – nice work.

The original version, as posted in February 2012 (was 2 mW / 20m band) allowed some minor DX
e.g. EA8 or 5B4, but within three years,  I could not make a single contact beyond the usual one-hop distance.

Finally I came to understand, how the efficiency of the parametric VXO could be improved:
all I had to do, was to insert two small inductors in series with the varactors –
once you got it, it’s all so easy...with now 5 mW on 15m band some real DX leaped into view.

Not sure, whether it’s about the somehow higher power now or the different band,
The more or less first serious attempt in the Black Sea contest was rewarded with a
first transatlantic QSO with Randy/N1KWF and the ARRL-DX contest two weeks later,
was good for another one into NJ with John/W2ID at 6050 km.
John had lot of fun with my exchange ( 599 001 ) and replied with something like 

“hi ur pwr 1W fb” –
I didn’t dare to tell him the truth, because of the heavy QSB.
These two OMs must have excellent ears and actually they did most of the work.

I’ve attached a schematic (Click) with a better resolution ( .bmp ) than that on QRZ.com,
but of course it’s up to you, whether or not you want to post that, which will require to edit the text a bit.

Will make some more photos, when I got it into an enclosure, but that will take some time, the TRX
is still under construction and I want to maintain its multiband capability, so far I’ve tested 17m and 15m, but 12m should work as well, but that requires careful planning.

Again, many thanks, Bert – keep your great blog going.

Tot ziens!

Peter/DL3PB

5 mW All diode TRCV crosses the pond

This winter Peter DL3PB built a new version of an

"All Diode" transceiver, the Paraski.

The new transceiver works on 15 meter and has an output of 4...5 mW

For Peter a dream comes true, by crossing the pond with milliwatts.
Peter  made a few QSO's with 5 mW, into an EFHW vertical on 15 m.

Peters rig has only diodes in the amplifiers and oscillators.
It's amazing, even for a milliwatter as myself. WOW.

Please visit the QRZ page of Peter (Click) to look at the schematic and a photograph 
of the Parasaki for 15 meter.

Data on the drawing:
PARASAKI_REV 15m
An "ALL DIODE" 15 m QSK TRANSCEIVER
PWR OUT 4...5 mW
WINTER 14/15   PETER/DL3PB


See the post of the 8th of February 2012 in this Blog,

for the 20 meter, 2...3 mW, Parasaki, all diode transceiver built in the winter of 2011 by Peter.

/QRP

I always use QRP, which is 5 watts or less in CW.  But I never use the tag /QRP.
In contest QSO's in CW, I rather send my call a second time in stead of /QRP.
In the BSCI contest I made a QSO with a station that was not in the contest.
I met a station from Guensey (GU) which is rather rare.

The signal was very strong, so I immediately reduced my power to 50 mW.
The FT-817 was set to 500 mW and I switched in the 10 dB attenuator.
The 10 dB attenuator reduces the power with a factor 10.
So my power was 500 mW diveded by 10 = 50 mW.
I received the usual 599 and I was happy to log MU0RGU.

But when I looked again at the S-meter after the QSO, I was surprised by the signal strenght.
Then I realized that I could have made the QSO with 5 mW.
In a contest it's (almost) impossible to make a second QSO (dupe).
But I decided to give it a try, because this was no contest QSO.
I switched in the 20 dB attenuator and gave my call PA1B/QRP, now using the tag /QRP,
now with just 5 mW.
To increase my luck, I decided to use the tag /QRP for a second QSO.
I thought that if I did not use the /QRP, I could not make the dupe, but MU0GRU came back for me
and I could make the second QSO, now with 5 mW. hi
Thanks to the friendly operator of MU0RGU.

I hope to receive a QSL. Until now I received a card for a QSO with 500 mW from Guensey.

Analysis of G3XBM's 40m WSPR spots with 5 mW

G3XBM left WSPR running with 5 mW on 40m for 24 hours.
Roger concluded that his signal was in the noise most  of the time.
He also concluded that he would need 2 W.
http://g3xbm-qrp.blogspot.nl/2014/01/40m-5mw-summary.html
The analysis below shows that the conditions changed dramaticly after the 7 spots with 5 mW.

The header of the table shows the Calculated  Lowest Possible Power in mW (Click for info), 
which is calculated from the used power (Pwr Sent  in mW) and the SNR.

The better the propagation, higher the SNR and

the lower the Calculated Lowest Possible Power will be.

The analysis
9 UTC gives the spots that were made in the hour from 9:00 till 9:59 utc.

This first line shows, that the power that was needed for the spots was 1 W down to 2 mW

In this hour, half of the spots that were made with 2 W could be made with 100 mW.

The white circles indicate the power with which half of the spots could be made.

The lower the power needed, the better the propagation.

From 9 utc till 14 utc on the 18th there are 11 spots with a calculated lowest possible power of 5 mW or less. So it was possible to make spots with 5 mW.

WSPR with 5 mW
From 14 utc Roger reduces further to 5 mW and over 24 hours only 7 spots were made, shown in the yellow coloured part of the table. In the red part of the table there are no spots since the power that was used is 5 mW. In the red part I show the receiving stations and their SNR.

Back to 2 W
You would expect more spots, since the 24 hours before showed many more spots that could have been made with 5 mW. But the conditions changed dramaticly.
The last part of the table shows spots that were made with 2 W.
At 20 utc on the 20th at least 500 mW is needed.
And at 5 utc and 7 utc spots could have been made made 5mW