Trying again the Waller Flag at IV3PRK – part 3
Testing it
I made some tests with my usual 1.843.2 oscillator (see test-oscillator.htm ) placed at about 200 m. distance from the Waller Flag in the NNW direction.
At first I checked the daytime noise level received by the vertical TX antenna: around –80 dB, while the oscillator signal is at -42 dB (but its source position is closer than to the WF).
![](./user/image/waller-flag-tests_archivos-image002.jpg)
With no antennas connected, the noise floor on the SDR-IQ receiver is -130 dB
![](./user/image/waller-flag-tests_archivos-image004.jpg)
Connecting the Waller Flag to the South direction, the noise level is still at -130 dB (without any preamplifier) while the 1.843,2 KHz oscillator signal is at -105 dB
![](./user/image/waller-flag-tests_archivos-image006.jpg)
The KD9SV BF994 x5 preamplifier
With the insertion of the new low-noise preamplifier by KD9SV, which gives a variable gain from 25 to 40dB, the signal jumps to -65 dB, while the noise level goes up to around -100 dB (that is about 10 dB of S/N increase). At first I tried also a rugged Norton 10 dB preamplifier at the tower base, but things were getting worse, so only the KD9SV (with its FES) before the transceiver is better.
![](./user/image/waller-flag-tests_archivos-image008.jpg)
Now turning the Waller Flag to South West it appears a 20 dB side null (-85dB)
![](./user/image/waller-flag-tests_archivos-image010.jpg)
Going further to the West the signal jumps up to about -62 dB
![](./user/image/waller-flag-tests_archivos-image012.jpg)
Turning the WF further to NW (towards the oscillator source) the signal reaches the peak of -58dB, but also with a 10 dB increase of the noise level.
![](./user/image/waller-flag-tests_archivos-image014.jpg)
For a further check the preamplifier has been switched off: signal decrease is 40 dB while noise decrease is about 30 dB confirming the S/N difference of about 10 dB.
![](./user/image/waller-flag-tests_archivos-image016.jpg)
Tests on the AM Broadcasting MW band
I made also a few tests on the MW broadcasting band. The nearest AM station in this area is Radio Koper in Slovenia, at a distance of 90 km., 166° direction, on 1.170 KHz.
Its best signal is correctly coming from this direction (South-South East): - 65 dB.
![](./user/image/waller-flag-tests_archivos-image018.jpg)
Curiously, the weakest one is not found on the back (i.e. towards North), but to the East: 30 dB down, almost in the noise, -95 dB! At the same time we see an increase of the signals on 1.152 and 1.179 KHz (two BC stations in Romania, 800 to 1.000 km at 83 degrees).
![](./user/image/waller-flag-tests_archivos-image020.jpg)
Effect of TX antenna detuning
All these tests were carried on at 3 PM. The next day I repeated the tests at 10 AM and got the same results. On the transmitting antenna (insulated vertical T at about 100 m. from the Waller Flag) I had added a detuning circuit, but no effect heard by switching it in and out. The SDR-IQ screen shows an increase of 2 dB on the signal when the TX antenna is detuned and the WF is pointed towards it, but no difference in the noise level.
The following picture shows the signal at -60 dB without detuning:
![](./user/image/waller-flag-tests_archivos-image022.jpg)
In the next graph, with TX antenna detuned, we can see a small increase of the signal to -58dB; only 2 dB, which cannot be detected by ear on strong signals, but could be useful with very low signals, under marginal conditions.
![](./user/image/waller-flag-tests_archivos-image024.jpg)