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Skywave · 26th Feb 2020, 7:41 pm

Since I like to 'do things' with R.F. circuitry, there are times when I would like to be able to assess impedance matching / mis-matching in a 50Ω system. To that end, I have a Telonic 'RHO' device. In use, you connect the reference Z to one port; the exciting source to a second port; the unknown Z to a third. This device has a BNC socket which delivers a d.c. voltage that is related to the degree of mis-match (or otherwise) between the reference Z and the unknown Z. In essence, this device appears to be a form of an impedance bridge.

Aside.
And yes: I do appreciate that it is 'old tech' - but it does seem to work! I am also aware that there are other methods / tools to meet the same requirement, but for now, I would appreciate any posts being restricted to this particular device: thanks.

I'm sure that this device could be used in a suitable circuit arrangement for a given 50 Ω system, with an analogue meter, calibrated in dB, to indicate the return loss.

Any ideas / suggestions etc. to meet that need using this device and in the described manner will be much appreciated.

Thank you.

Al.

26th Feb 2020, 7:41 pm	#1
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Idea for a method of Z measurement. Since I like to 'do things' with R.F. circuitry, there are times when I would like to be able to assess impedance matching / mis-matching in a 50Ω system. To that end, I have a Telonic 'RHO' device. In use, you connect the reference Z to one port; the exciting source to a second port; the unknown Z to a third. This device has a BNC socket which delivers a d.c. voltage that is related to the degree of mis-match (or otherwise) between the reference Z and the unknown Z. In essence, this device appears to be a form of an impedance bridge. Aside. And yes: I do appreciate that it is 'old tech' - but it does seem to work! I am also aware that there are other methods / tools to meet the same requirement, but for now, I would appreciate any posts being restricted to this particular device: thanks. I'm sure that this device could be used in a suitable circuit arrangement for a given 50 Ω system, with an analogue meter, calibrated in dB, to indicate the return loss. Any ideas / suggestions etc. to meet that need using this device and in the described manner will be much appreciated. Thank you. Al.