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.
Would be interesting to do a test in IM67 when conditions are good. I had G4APB in the summer on 40.013 several times and a station in Paraguay beaming at the US using very little power as well as off beam on a multi element aerial. When you were in wspr mode the other day before changing to ft8 your, signal looked very strong.
ReplyDelete73's
Hugh
Another attenuation option would be to use a simple voltage divider (totalling maybe ~1k) on the input side, i.e. between sound card and FT-817.
ReplyDeleteM0RSU