During the build of the Band Pass Filters it has become obvious that my little miniVNA is just not up to the job. Because of this (after some advice from Bob 5B4AGN) i will be embarking on building one of these
Construction of the band pass filters continued today, progress has been slow recently as i needed some more parts (M3 10mm bolts and some M3 nuts), I also had the problem of finding some appropriate coax to use for the internal connections. As luck would have it i have a couple of barely working Wifi antennas that have some nice long leads of very thin coax, it turns out that the coax is RG-174, perfect for my short internal connections on the BPF’s.
My large 7 segment displays have arrived, these are 2.24″ tall and will be eventually be used in couple of large band readouts for the M0XXT contest station.
They are yellow and of the common anode variety. Should look pretty nice once the project is finished. If anyone knows of a suitable enclosure to hold 3 of these plus associated circuitry please let me know.
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