EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: IDEngineer on December 27, 2020, 06:56:10 pm
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I'm looking for a ready-made DC block to protect the input of my spectrum analyzer. The SA goes to 13GHz and I'd like to reach as low as possible, which may require more than one block. I'd like to go N male to N female.
The Weinschel 7003 is pretty wide for the top end (9KHz-18GHz) but I'm having trouble finding where to purchase one. I presume there are other reputable units out there but searches aren't turning up a whole lot. The usual sources (TEquipment, Saelig) don't have much in terms of selection.
I'm also wondering about options below 9KHz.
Yes, I could build one, particularly for the lower frequencies, but for the high end I suspect dialing in the wide range impedance performance is more than just soldering a large value cap.
Any recommendations appreciated. Thanks!
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Have a look at MiniCircuits blocks.
Be aware that DC bloc!is won't completely protect the input. When you connect a DC voltage there will be the obvious RC exponential transient. The larger the capacitor, the bigger the transient, i.e. the lower the cutoff, the bigger the transient.
It is good practice to measure a source before connecting it to an SA input.
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Yep, that's my standard practice. I check signals on a scope before connecting them to an SA. But I've long thought it would be good insurance to ALSO have a DC block in the circuit. A slip of the finger on the touchscreen of the AWG while adjusting amplitude, for example, could instead tweak the offset and result in a DC bias. (Those touchscreen "buttons" are darned small.) SA's can be expensive to repair, preventing a single damage incident could more than pay for a DC block.
I looked at MiniCircuits, but IIRC they only have one N connector option and it has a rather high bottom frequency.
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I'm a belt-and-braces guy too :)
I usually leave a sacrificial N-SMA converter on the SA, and attach an MiniCircuits 10MHz-18GHz SMA connector blocks to that. If I want below 10MHz, I can use other instruments.
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I'm like tggzzz, I use SMA blocks. I know that's not what you asked for suggestions for, but they are way easier to come by. I don't have anything that wide range to suggest (so why am I posting?). My go-to are some MiniCircuits 100k-8G that I have: BLK-89-S+. Last N DC block I bought at work was MiniCircuits; seems like whenever I've looked, they've been the best bang for the buck. But that one was only needed for SATCOM. When I need to go higher I have an HP 11742A 45M-26.5G, but I don't often pull it out because it would be expensive to replace (I got it relatively cheap on eBay) so I'm overly careful with it.