02-01-2022, 01:45 PM
(31-12-2021, 06:23 PM)VK4ADC Wrote: The spec analyser screen shows -47dB at 2F but looks to have about 2dB loss at 144 ?
Hi Doug,
The SA screen doesn't show the loss accurately when you have a large range to look at. The measured loss was no more than 0.2dB for the filter, certainly not 2dB! - that would be bad
The coils are hand wound 1.2mm wire and the caps are ATC 100 types as supplied with the kit.
The intent is to assemble and test this kit with parts supplied to see if actually works as advertised. After that I might make some mods to improve its behavior if needed.
i.e. the bias circuit has no temperature compensation but that can be achieved by changing out the 10k resistor in the bias voltage divider for a 10k NTC that I'll place in close contact with the heat sink.
cheers
Tim