I bought three of those directional couplers on eBay and they work very well for measuring PA output power. The coupling value can be selected 10/20/30/40dB. (and some more) Those directional couplers are sold by many sellers and also on amazon & Co. for a few bucks. https://www.ebay.de/itm/1stck-Mobiltelefon-RF-Koaxial-Richtkoppler-800-2500-MHz-200W-10-20-30-40dB-de/264323112502?hash=item3d8ae29e36:m:mT6rnKMBsPYpjotZjzsa11w At "Antons Funkperlen" website are photos from the inside: http://funkperlen.blogspot.com/2017/11/ein-2500-mhz-richtkoppler-fur-7-euro.html Edit: attached a picture of a measurement on my 30db coupler VY73 DB8TF