Re: RF Power #chat

Andrew Lenton

Hi Just to give an update to my low power issues, I first built the U3S with a 20M LPF only, since then, I have bought the relay board and built the 160m, 80M, 30M 17M 15M 12M and 10M LPF. I have measured all the filters, using a network analyser, and my newly purchased Signal Hound in conjunction with the SDR KITs development board. I found all low pass filters to have a through loss of less then 0.3dB, however, the 30M and 20M low pass filters had a loss of 3dB.

On the 20M LPF there are 7 components, 3 coils and 4 capacitors, 2 X 180 pF and 2 X 390 pF, when measured the 390pF were only 327pF so I can only assume incorrectly marked, replacing these capacitors brought the through pass loss down to .2 dB at 14.35MHz. Solving the low power problem.

73 Andrew G8UUG

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