6 Comments
User's avatar
S.F. Bosch's avatar

This is great. We just purchased some BNCs for a project and was curious as to why they *had* to be 50 ohm. Could not find the information easily.

Expand full comment
Tanj's avatar

When I learned coax it was 75 ohms for a good match to dipole antenna, and most stuff you find related to TV is 75. I was surprised much later to encounter 50 ohm equipment. Thanks for explaining why!

Expand full comment
CitizenSleeper's avatar

I see coaxial cables being used for external clocking or measuring clock signals on the FPGA. Is this the reason why as the terminations comes with the cable rather than using a bare cable?

Expand full comment
Vikram Sekar's avatar

It’s very important to terminate cables properly to avoid reflected signals

Expand full comment
CitizenSleeper's avatar

So for a clock/frequency generator, generating various frequencies, should there be a way to have an adjustable termination as we do not know what is connected to the frequency generator before hand?

I just started learning antennas and transmission lines and it is a rabbit hole. Now I partly understand that the signal aberrations that I see on my scope is due to impedance mismatch etc.

Expand full comment
David Holmer's avatar

Fascinating. I wonder if 50 ohms is the same power vs loss point for PCB trace transmission lines. Or are they different and 50ohms is purely from coax.

Expand full comment