Re: Switching a Tek TDS 5204 to 50 Ohms input impedance - Strange!


Hi Raymond , I have a couple of TDS's , a 744 original version and a 420A . Both are protected on the 50R input setting so I would expect all others to be the same . I have noticed this behaviour when using the 50R input and until I got used to it having wondered what was happening at first I much prefer it to the action taken by the 7A29 7k plug-in which just disconnects the input - and you need to disconnect to reset it.Regrettably I am just a hobbyist pensioner nowadays so my experience with anything newer than a TDS744 is zero , give me 500 series or 7K series even a 661 and I am happy
Brian Skilton

On Monday, 15 June 2020, 23:04:51 BST, Raymond Domp Frank <> wrote:

On Mon, Jun 15, 2020 at 04:27 PM, Brian wrote:

Hi , sorry to but in but I think Tek have got it right . The scope has no idea
if the voltage measured is from a hi-impedance current limited source or a
low-impedance constant voltage source with little or no current limit . The
50R termination in the scope is expensive and difficult / costly to repair so
they play safe to protect it . I would not be complaining about that .
regardsBrian Skilton
These were my thoughts exactly. I wanted to add that the 50 Ohm input may be protected but for a fast 'scope, the circuits would be tiny, so difficult to fully protect. Unfortunately, I couldn't find (the BW of) a TDS 5204 so decided not to write my reaction. Probably an MSO5204?

On Sun, Jun 14, 2020 at 06:26 PM, Jokken Feldhaar wrote:

Did theĀ  engineers at Tek really commit this big time error? I cannot believe this!
So, not an error at all, just clever design!


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