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Port ratings


Marcus Gustafsson 2020/05/13 13:53

Hi all,

what would the port ratings be on the NanoVNA-V2?

I mean the max x VDC and y dBm RF you see on the yellow stickers on instrument ports.

Looking at the schematics one could assume that the 10uF capacitors after the SMA connectors on both ports are 35V rated or lower? If so, how low?

Port 1 goes directly to a RF input on a RF switch which specifies absolute max to 28dBm.

Port 2 has a pi attenuator of 0402 resistors before the antenna input of a RF switch. What are the power rating on 0402 resistors? I guess 1/16W ie, around 18dBm but first resistor does not take it all so I guess a bit higher, 20 dBm? The max rating of the RF switch antenna input is not specified in the datasheet but it ha the same P1db point as the other RF ports so can we assume 28dBm here as well?

So 10VDC and 20dBm RF for both ports?

Best regards
Marcus

hwalker 2020/05/13 17:05

On Wed, May 13, 2020 at 01:53 PM, Marcus Gustafsson wrote:

Looking at the schematics one could assume that the 10uF capacitors after the SMA connectors on both ports are 35V rated or lower? If so, how low?
======================================================

Per Gabriel:

"The DC blocking caps are 10V ones, so I'll say probably up to 5V DC at the ports is safe subject to transient current limits."

- Herb

OwO 2020/05/14 12:42

20dBm + 5V DC is safe. Capacitor rating is >= 10V. I wanted to specify
higher rated caps but there is a global shortage of certain MLCC
capacitors right now. Maybe in the future.

On 14/05/2020 08:05, hwalker wrote:

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