Yes, very true, my statement made is seem like 50 Ohm impedance was an absolute, but it is simply to accomodate the specified input impedance of the test equipment. Most RF test instruments use either 50 or 75 ohm native input impedance simply to accomodate an intended application. Very few amateur techs posses the collection of attenuators and pads to transform an odd impedance to one compatible with their test instrument.
In reality, it depends on the circuit under test. Then again, I find absolute level measurements are seldom critical. I have fount that in most Transceivers, circuit implementation ditcates the native impedance of Internal RF paths between components, so absolute level measurements there are challenging, which is why the Japanese service manuals typically document the internal IF levels in terms of gain in dB from the previous stage or relative to the specified Rx or Tx source input.
Cheers
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73's
Dave - KB7JS
73's
Dave - KB7JS
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