8m ISM experiments continued

Today I intend to reduce my 8m WSPR power to 10mW ERP and use the call 8M3ISM to see who, if anyone, can still spot me locally. Yesterday, with 5 local monitors, I was widely spotted with 1W WSPR. Judging by the reports yesterday, things will be far harder today. 

Although Keith yesterday told me of an easy way to reduce power of the FT817ND by 20dB using the power slider in WSJT-X, I cannot see a way to do this with VOX control and a SignaLink USB, so I will add a 20dB attenuator temporarily. 

I need to work out the correct values for a 20dB pad, which will go right next to the rig so there is no radiation risk from the coax cable. As I intend to keep the 1W power setting from yesterday, I need to ensure the attenuator is suitably rated for power handling. Looking at the calculator, I can use 100 ohm resistors in series and parallel to get the values and power handling. The calculator is on the site shown.

See https://leleivre.com/rf_pipad.html .

UPDATE 1215z: 10mW WSPR running with the callsign 8M3ISM.

UPDATE 1656z:  G4AWP , M0RSU and G4BAO have already spotted my 10mW ERP 8m WSPR signal. G4AWP and M0RSU are about 17km away. None of these stations are using 8m antennas!

Sunspots - Tuesday November 22nd 2022

Solar flux is 117 and the SSN 83. A=10 and K=1.

8m ISM experiment

At the moment I am doing some local tests to see if people can copy 10mW ERP on 8m locally. This is the UK ISM limit. As calibration, I am sending 1W WSPR on 8m before trying 10mW ERP. Initial tests suggests this is too low to be copied, but might just be possible with 2el 8m antennas. 

UPDATE 1928z: This is an update on the 8m ISM tests locally so far.  At the moment, I expect to switch to 10mW ERP WSPR later this week with the call 8M3ISM.  A 20dB pad will be added right next to the FT817ND.

• Judging by the 1W WSPR reports so far, I feel it is unlikely people at any distance will copy my 10mW ERP signal.
• One of the issues is a high local noise floor.
• With 8m horizontal antennas, I suspect many would copy my 10mW ERP WSPR.

When the change is made to the 10mW ERP WSPR I shall announce this here with my conclusions by the weekend.

Sunspots - Monday November 21st 2022

Solar flux is 119 and the SSN 72. A=6 and K=2

8m QRP WSPR

In preparation for my local 8m QRPP WSPR tests later this week, I have now QSYed to 8m WSPR. I am on 40.680 MHz with my WSPR tones at 1500 Hz HF in the middle of the WSPR slot. 

This means the actual WSPR transmission is on 40.6815 kHz.

Jason, M0NYW is doing local tests with 8m WSPR at 10mW ERP on 8m under ISM regulations. He is producing a coverage map around the local area. He is doing a blog.

See https://m0nyw.blogspot.com .

Cactus - NOT amateur radio

My wife has her birthday later this week. This cactus is always in flower for her birthday. It is in our hall. 

I think it is called a Christmas cactus, although ours is always in flower in November.

Curious cat - NOT amateur radio

My French daughter-in-law has a cat that loves exploring bags. Yesterday, we went to London to see her and our granddaughter..... and the cat.

10m QRP (500mW) WSPR TX (Sunday)

With 17 stations already spotting my QRP by 1200z, this is a good day on 10m WSPR. Let's hope I get spotted in the USA later.

8m FT8 at 2.5W TX (Sunday)

Since learning yesterday that I was running 2.5W and not 5W with 3 bars on my FT8, I can report good results this morning on 40.680 MHz FT8. 

Results suggest there is some Es. See map.

RF attenuators

Luckily, there are several online calculators to work out what values of resistor are needed for a given degree of RF attenuation. In the past, I have added attenuators right on the output of my FT817 to get really low power with WSPR on HF bands. 

Starting tomorrow, I hope to do some very low ERP tests on 8m locally. Initially, I shall be sending 8m WSPR with my normal power, to make sure locals are looking in the correct place. Later, I am proposing to send 10mW ERP 8m WSPR with a different callsign to see who can still copy me.  This should give some idea of what would be possible on the 8m ISM band with very low powered beacons.  

Recent OFCOM statements have indicated to me that such operation would be legal without a licence as long as the technical requirements and IR 2030 are met i.e. 10mW ERP at 8m. 

If successful, I think many more UK people could legally experiment at 8m on the ISM band albeit with very low power. I know that Jason M0NYW is proposing such tests in his local area. In my view, this is exactly what research is all about. This is not amateur radio, but it is very much radio by amateurs.

Now, I am no legal expert, so you have to decide what the rules indicate.

See https://leleivre.com/rf_pipad.html .