QRPp How is it possible

When I started as a HAM, 20 years ago, I used my homebrew transceiver HM7, from Solid State Design, page 214...218, with an Inverted Vee, to work many different DXCC countries in Europe in CW. Because my power was only 500 mW, I had to look for stations, that I received with 599 or more, so the other station could hear my QRPp signal of 500 mW.
During daylight hours my RST would be 559, or even lower.
Please notice that a power of 500 mW is only four S-points weaker than 100 Watts.
See the PA1B QRPp page.

D and E layer
The radio wave is not attenuated when it is reflected by the E-layer. (Total reflection) But during daytime the signal is attenuated by the D-layer, when it passes through the D-layer.

During daylight hours, the signals are attenuated by the D-layer, which is absorbing

I discovered, that when darkness fell, the signals from the south of Europe would be very loud. So this made it easy, to make QSO's over a distance of 1000 km or more. When the D-layer disappears during the night, the signal can reach the the E-layer without attenuation in the D-layer.

The E-layer reflects the signal without attenuation

When the D-layer disappears, there is no attenuation in the radio path. The signal is reflected by the E-layer without attenuation. The attenuation of this sky wave is (only) 6 dB for a doubling of the distance. So the signal will be very strong.
At first, I did not realize, that my own QRPp signal, could also be an earsplitting 599, until I got genuine report from Italy, that my signal was S9, while using just 500 mW.

How low can you go

I was wondering, what the lowest possible power would be, if I would reduce my power in that situation with this excellent propagation.

If I reduced my power, so my RST would be 559, the difference is 4 S-point. This is a reduction in power of 4 x 6 dB = 24 dB which is 4 x 4 x 4 x 4 = 256.
So I could reduce the the power from 500 mW to about 2 milliwatts.

I was surprised by the low value, that I calculated, but this value is very realistic.
From 2001 on, I made many CW contest QSO's over more than 1000 Miles with 2.5 mW and 5 mW,
using PA1B homebrew attenuators.

I discovered that the frequency must be absolutely clear, when you use very low power.

30th OQRP contest with VLP

Homebrew
I participated in the 30th OQRP contest in the VLP category (less than 1 watt) and had fun with my homebrew 7 MHz CW transceiver.
The TRX is the HM7, that I built many years ago. Click on the HM7.
This rig comes from "Solid State Design for the radio amateur" page 214...218.
The antenna is an Inverted Vee.

AGC
My homebrew transceiver has no automatic gain control (AGC), which is a real pain in the ears, when the received signal is strong, such as RST 599 or even more.
In this contest I experienced again, that in a receiver with manual gain control, strong signals are very strong in the headphones.
With this receiver you are always too late with strong signals.

Reports
The report in the OQRP contest is RST, serial-no./ category e.g. 559001/VLP. This makes more fun than the usual reports with 599. You must be very keen on the received RST. All QRP stations that I met, gave a RST lower than 599. The QRO station gave 599.

My received RST
I received 519 (1), 449(1), 559 (3), 569 (1), 579 (3) 589 (1) and 599 (3)
The signal reports from 519 to 589 are a real RST.
Somtimes the other station was much weaker than QRM from other stations, but still the exchange was easily copied.

DXCC
I made only 14 QSO's. My DXCC score: DL (11), OK (1), S5 (1) and SM (1).

On sunday we went to "Fort bij Vechten" to visit the fort, during the open day.

Propagation, activity and antenna

The order of importance is: Propagation -  Activity - Antenna

 When I started as a HAM in 1990 I used a homebrew QRPp transceiver for 7 MHz, which I call the HM7 and an inverted Vee antenna.
In the 10 years that I used this CW transceiver extensively, I worked many European countries with a power of only 500 milliwatts in many normal QSO's and many contest QSO's. The excellent design comes from the book solid state design for the radio amateur.

I used this transceiver as a homestation and on holiday. Homebrew, QRP and CW (morse code) is a fabulous combination.CW is the most intriging mode of all. I noticed that you probably can not come closer to the signal, than in CW.

During the years that I used this TRX, I had great fun and I noticed that the activity on the band is more important than the antenna. With 500 mW the signals of the other stations must be S9 or more. Especially contest stations are eager to work everyone, so many QSO's can be made in a contest.
Further I discovered that propagation is more much important than the antenna. The Inverted Vee is not the best antenna, but the daily changes in the propagation can not be beaten by any antenna.

So to me, the order of importance is: Propagation -  Activity - Antenna