We Have Filters!

40m Bandpass FilterA Bandpass filter is invaluable for club/group activities and the “sting” of their price can often be reduced via a “group buy” or a nice word with your local club.

Back in 2016, a group purchase included 40, 30, 20 and 17m filters and this ensured that multiple bands could be active without any QRM.

I was able to borrow a miniVNA Pro which allowed for plotting SWR, Resistance, Loss etc and dump it to an image file.  The graph below shows the performance of the 40m filter across the HF spectrum:

40m Bandpass Filter HF PlotHere are some additional plots: (1) 40m filter at 30m , (2) 30m filter at 20m , (3) 20m filter at 15m , (4) 17m filter HF plot

Bandpass Filter PlotsI also used a narrower sweep to read the individual band attenuation specs: 70db on 160m, 48dB on 80m, 38dB on 30m, 80db on 20m, 83dB on 17m, 73dB on 15m, 70dB on 12m and 70dB on 10m.  Insertion loss is 0.5dB on each filter. During tests, a variety of plots were taken and each filter offered a very respectable set of figures which will make operating more fun/productive from now on 🙂

Post-blog-note: After several outings /P, their performance has been confirmed and using these makes the world of difference!