Coax connector 50ohm v. 75ohm C band

Ideally you need the same source and load impedences as well as connectors and cable type.

If you have a mixture, the effect is partially reflected signals which results in amplitude ripple due to partial signal cancellations/additions across the frequency band.  This will add errors to measurement accuracy - but it depends what you are trying to measure or observe - if you are simply looking to see a particular small carrier on a spectrum analyser then maybe the ripple errors and absolute levels don't matter.  The partial reflections also cause mulitpath delay effects, like shadow images on analogue TV and inter-symbol interference in digital systems.  Similarly don't crush coax cables at regular intervals (e.g. using wall clips, clamps or cable ties).

If you are connecting a C band BUC with a coax output via coax to the feed OMT you should must use 50 ohm Andrew Heliax cable (or similar) and Andrew 50 ohm N type connectors at both ends.

Be aware that 50 ohm N type and 75 ohm N type plugs exist.  Never put a 75 ohm N type plug to a 50 ohm N type socket - the centre pin won't connect properly as the 75 ohm centre pin is very slightly smaller diameter.

I agree with the desirability of using 50 ohm for all C band RF measurements.

Best regards, Eric.

Thanks Eric..

Hi Oasis,
  will appreciate if you could send me the link of the article you mentioned.

Thnkx and regards