Greetings from cm3kma, I comment that last month I had to readjust the TPRD-1554 in the place where they are installed and the only tool I have to be able to do this readjustment was a modest VNA of the brand (Nanovna-F HW3.1 Deepelec ), which at the end is the same principle of the NANOVNA of this forum, in the attachment are the photos of the notches and the band passes corresponding to the frequency (TX: 145.210 and RX: 144.610) of this repeater that we have mounted on the hill de candela, g¨¹ines, mayabeque, cuba.
If you look at the photos, the nanovna configures the range to be measured in such a way that the jumps were from 10 to 10khz, starting at 144,500 to 145,500Mhz since it is the range assigned for the repeaters in Cuba and also to coincide with the 101 points of the vna for jumps of 10 in 10KHZ.
Very important to have greater precision in measurements of this type, I recommend that you recalibrate your nanovna in the range that you are going to work with.
I hope my humble contribution will help you 73.CM3KMA
