Owen Duffy Inscribed thus:

If I have followed the thread properlty, you have a VSWR meter and you
have now decided to replace the coupler. The meter movement is
actually intended for another project.

It might not have occurred to you that if the diode voltage drop is
small wrt the RF voltage being rectified, that the 0 to 100 meter
scale could be taken to be rho (the magnitude of the complex
reflection coefficient) in percent. But, there is an if in there,
verification is needed.

The calculator at http://www.vk1od.net/calc/tl/vswrc.php accepts rho
as an input (it is called the voltage reflection coefficient in the
calculator). So, if you were measuring SWR and you had 'set' the fwd
direction for fsd, then read for example 15/100 reflected, rho=0.15
and the calculator will tell you that VSWR=1.35.

Owen

In other words, half scale will be 3:1 !

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Best Regards:
Baron.