I build the 40dB tap from the same QST article as my powermeter.

To make it useful, I need to measure the coupling and insertion loss, so here goes. S1 and S2 are the through ports, S3 is the tap. It's pretty flat over 7-433MHz, with a through loss of <1dB and a coupling of 33-34dB.

Test setup is the FT817 in FM mode and lowest power as the signal source, through a 20dB pad to the source port of the coupler, the powermeter connected to the measured port, and my better 50R termination for the remaining port.

So, now I can connect a dummy load to S2, my new ubitx to S1, and the power meter via a 20dB pad to S3, shout oooollllllla into the mic and read -16dBm off the power meter.

Thats -16dBm after 20dB of attenuation and a coupling of -34dB, so I'm ooolllllaaa-ing at -16+20+34=38dBm, or six-point-something watts. Maybe a bit low, bit it'll do for now.

F [MHz] S1S2 [dBm] S1S3 [dBm] S2S3 [dBm] SRC [dBm] loss S1S2 [dB] loss S2S3 [dB]
0 7.15 4 -30 -30 4 0 34
1 10.00 4 -30 -29 4 0 33
2 29.00 5 -29 -28 5 0 33
3 50.50 5 -28 -28 5 0 33
4 145.50 4 -29 -29 5 1 34
5 433.00 3 -30 -31 3 0 34