136kHz with a vertical antenna ....8uW ERP

Having simply tuned and matched my 5m coax feed to the 28MHz halo (the halo is used as a top capacity hat) I'm now putting out the grand level of 8uW (+/-3dB) on 137.675kHz in QRSS3 from my 2W out beacon TX.  Tuning was with 1.2mH wound on a small piece of ferrite in parallel with some fixed and variable capacitance. Matching was via a 3C90 toroid transformer. Field strength tests a few km away from the QTH suggest that the ERP from the earth electrode antenna is higher than this vertical, which is a bit disappointing as it suggests the vertical is, well, poor.