I touched up the solder joints on all the LPF capacitors and toroids, and also adjusted the turns spacings on L401 to match more closely the photo in the assembly manual.? Reconnected the radio to the QRP Labs dummy load.? After this, the RF sweeps and LPF sweeps looked very good, in terms of BPF peak frequencies and LPF cutoff frequencies and stopband levels.? There were, however, no improvements to the output powers, which ranged from 1.3W (15m) to 3W (17m) before and after these tweaks.
Next I removed the ShortStopper from the power cable, since I am past testing for power-ground shorts.? I ran the power tests again, and saw improvement across the board, from 1.7W (15m) to 4.3W (17m).? "PA voltage" was in the 7.5V range on all bands. The radio draws 120mA on receive and 900mA in transmit, according to the meter on my power supply.
After this, I followed Hans' tip in the "52 tips" video and squeezed the turns together on the antenna-side toroids for LPFs 1 and 2, which cover 17-10m.? There was no improvement in output power; in fact, 15m went down.? I observed that this change to the toroid made the LPF narrower, putting the test frequency out of the passband into the transition band, hence decreasing the output power.
I am happy enough with 17m and 20m, but would sure like to get more than 1.7W out on 15m.? Any suggestions?
Thanks very much,
Eric
