Products > Test Equipment
Another radio amateur about to buy a DSO ...
tggzzz:
--- Quote from: Mike99 on November 16, 2023, 12:29:32 am ---
--- Quote from: ebastler on November 15, 2023, 01:13:17 pm ---
--- Quote from: 2N3055 on November 15, 2023, 01:02:43 pm ---Anyways, it shows 50Ω path is not made by simply putting 50Ω terminator in parallel with 1MΩ/20pF input...
--- End quote ---
This would be a nice opportunity to demonstrate the difference.
@Mike99, any chance you could repeat the measurement with the scope's input set to 1 MOhm and an external 50 Ohm pass-through terminator? Thanks!
--- End quote ---
I don't have a pass through terminator, only a 6dB BNC attenuator.
Mike
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A 6dB passthrough attenuator followed by the imperfect internal attenuation will be better at reducing VSWR than an external terminator. That technique is frequently used inside equipment where components/subsystems have poor impedance matching.
Basic principle: gain is easy and cheap, wideband matching is difficult and expensive. But don't stick an attenuator in front of a low-noise front end, of course :)
Mike99:
I have made some more measurements.
First was the 50 ohm input bandwidth, measured using an RF millivoltmeter:
Next was input VSWR. The graph compares the 50 ohm input with the 1Mohm input, the latter using a T piece with a 50 ohm load.
Finally, the impedance of the 1Mohm input.
Mike
Orange:
Hi Mike,
An impedance plot for 50 Ohms would make this information complete :-)
Mike99:
--- Quote from: Orange on November 16, 2023, 12:52:39 pm ---Hi Mike,
An impedance plot for 50 Ohms would make this information complete :-)
--- End quote ---
OK I'll do that later today.
Mike
dshorthill:
I use this device to monitor the RF output of a 1 kw ham amplfier on my 1204xe Siglent scope. I have a bnc t with a 50 ohm termination on the scope end. Works great.
https://www.ebay.com/itm/193686855709
Dave
k1xd
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