Going a bit off topic here, but I have fitted the filter module for a friend and it is a relatively straightforward job. However, I would recommend a magnifying glass and a fine tipped soldering iron as there is one very fiddly bit of soldering to do. Believe me, this filter makes a big difference, well worth the money. It should also be remembered that end fed half waves fed via a tuned circuit, like the one from Sotabeams, also provide excellent out of band rejection for what is a very wide front end on the 817/818. The Fuchskries from QRPproject is a multi band EFHW tuner that works from 80-10m.
https://www.qrp-shop.biz/epages/qrp-shop.sf/de_DE/?ObjectPath=/Shops/qrp-shop/Products/Vfuchs
It is very popular here in Austria and Germany, and in conjunction with the SWR meter on the 817/818, it is very easy to tune the antenna safely. I made another thread on the construction of this kit here:
If you need an English instruction manual then send me a PM and I can let you have a link.
de OE6FEG / M0FEU
Matt