EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: 6SN7WGTB on April 21, 2022, 01:01:02 pm
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I have the IFR 2025 and have noticed something I do not understand - can someone explain/help...?
As you wind up the RF level/output there are occasional clicks of reed relays as I presume attenuators get switched out or different output stages get switched in.
When I have it connected to an RF mV meter (input impedance 1MΩ plus tens of pF), and with the mVM on a set range of say 3V, and I wind up the RF level towards 1V, the meter smoothly reads up to that 1V from basically zero (through the ranges of the mVM). And going through several relay clicks on the 2025.
At that 1V level, continuing to increase level (to say 1.01V) causes a typical click and this is accompanied by the mvM reading DROPPING by about 20%. Ramping the RF level on the 2025 causes the mVmM reading to smoothly continue back up.
Thinking something might be duff with the 2025, I then attached a 50Ω through load. This pretty much halves the reading on the mVM as expected (the 2025 is set to 50Ω). So the 2025 would not appear to be duff at all.
Now as I ramp up through 1V on the 2025 (and the click) the meter shows no perceptible discontinuity.
(Tried this from 10kHz to 20MHz and same effect at same RF level)
Using an AVO 8 to measure the RF output (at a low freq. the AVO can cope with), the discontinuity through the 1V 'click' is very small.
Could someone explain?
Thank you.