For CQ WPX this year i built two sets of high power coax stub filters to allow the M0XXT team to enter as Multi-Single.
These stubs performed reasonably, although there are some improvements i plan on making for the final design to be used in conjunction with the Band Pass Filters already under construction.
Expect a full article on the coax filters soon.
(P.S. Fitting over 80 PL-259’s is not fun)
I started construction of the first of two automatic band pass filters tonight. These will be used in the M0XXT contest station in conjunction with high power stub filters to allow us to run a proper Multi-Single or Multi-Two station.
These are similar to the Dunestar 600 devices, however they use the W3NQN filter design so the performance is superior to the Dunestar’s. They were designed by Bob Henderson 5B4AGN, who had some professional boards and cases made up.
They employ a very clever motherboard system, so the filters can be removed/replaced easily.
The photo is of the first, nearly complete motherboard
Progress on the band pass filters is progressing nicely, the second motherboard is almost complete and winding of the coils for the first set of filters has begun. Hopefully I should be starting on tuning the filters shortly.
Here is a quick pic of the L1 winding for 40m
