needairtime
Member
Granted PL259/SO239 are bad at UHF, has anyone got ideas how to identify at least somewhat "acceptable" SO239 F-F couplers by visual inspection?
I got a coupler and well the first thing I tried doing is feeding it through a VNA to see what its characteristics are like. It seems that while it's okay at HF, it's bad at VHF, and plain awful at UHF. Smith chart spirals out. In fact if I take the coupler out and just hand hold the PL259 center contacts and shields together, it gives me a better SWR. Granted I have a lot of adaptors on the signal path, but it's strange that the Smith chart spiral is much more packed in the center when just hand holding the two PL259s together than when using the coupler.
The behavior of the SO239-SO239 coupler is worse than a CB SWR meter with two SO239s that I did the same experiment on - the CB SWR meter was good at HF, passable at VHF, and bad at UHF.
Would be nice to get a coupler that works acceptably at UHF - Perhaps it's just impossible to tell by looking at them?
I got a coupler and well the first thing I tried doing is feeding it through a VNA to see what its characteristics are like. It seems that while it's okay at HF, it's bad at VHF, and plain awful at UHF. Smith chart spirals out. In fact if I take the coupler out and just hand hold the PL259 center contacts and shields together, it gives me a better SWR. Granted I have a lot of adaptors on the signal path, but it's strange that the Smith chart spiral is much more packed in the center when just hand holding the two PL259s together than when using the coupler.
The behavior of the SO239-SO239 coupler is worse than a CB SWR meter with two SO239s that I did the same experiment on - the CB SWR meter was good at HF, passable at VHF, and bad at UHF.
Would be nice to get a coupler that works acceptably at UHF - Perhaps it's just impossible to tell by looking at them?