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hi all,ive an old hp limitre from an old rectum paralyser,its a 5086-7282 0- 1.8ghz,is it worth putting this on the input port of my nanovna as a protection,is it a goog idea or bad?,73.

Spell checker smile of the day...... :-)

This is a 10W limiter
is similar to yours, so I would suspect you could use it on CH1 without issue as long as you re-calibrated with it attached.
...Larry

cheers larry,looks like it cant do any harm using it then,may save the vna front end incase of a cock up.

looking at it,as i right in thinking they provide an overlod path to ground?,ie shunt or thru/series,ie do i need to ground the body or will it do that via the sma conectors on it?

Read up on the various messages that talk about the reference plane.
The limiter will limit when it is connected to the Nanovna but if you are performing antenna testing, if the Nano is floating, it becomes part of the antenna system and readings can be incorrect.

On Tue, Dec 10, 2019 at 05:20 AM, <nanovnauser@...> wrote:

hi all,ive an old hp limiter from an old spectrum analyzer. Its a 5086-7282 0-1.8ghz, is it worth putting this on the input port of my nanovna as a protection,is it a goog idea or bad?,73.
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The 5086-7282 is a diode limiter. Diodes are non-linear devices and can introduce uncertainties in your measurements. The input port of the NanoVNA is CH1 and placing the limiter there would protect the port from signals greater than 30 dBm (if I remember the specs for the limiter correctly). I believe 30 dBm might be higher than the NanoVNA is rated for and would give you a false sense of security.

I can't recall any commercial or amateur VNA designs with a limiter on the output port (NanoVNA CH0) because of the non-linearity issue previously cited.

- Herb

I may stick it on ch0 and do some back to back like for like,ie with and without comparisons.