Re: Poor Quality 50 Ohm Load - Where to get accurate ones?


Jim Lux
 

I used Pasternack as an example of what's available at a variety of retail price points. Not as a recommendation of what to buy.

It was too much trouble to hunt through Keysight's website to look for loads, calkits, etc., but yes, they have them, and I think I'd trust them more than Pasternack.

On 8/16/20 8:17 AM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:
On Fri, 14 Aug 2020 at 02:34, Jim Lux <jimlux@earthlink.net> wrote:

On 8/13/20 5:52 PM, Glen Jenkins WB4KTF wrote:

The 50 OHM load (SMA-Male) that came with my nanoVNA-H4 measures 51.13+
ohms. Not a good start for calibration. Where is a good source for GOOD
loads that are accurate?



that's a VSWR of 1.023:1 and a S11 of -39dB
That’s true only if the reactance is zero.

How much are you willing to pay?

Pasternack has a SMA Male load (PE6002) for $38
Many RF engineers call them Pastercrap. I tested 10 Pastercrap loads and
not one met the specification.


For $1900 they'll sell you a 3.5mm load for a cal kit

up to 4GHz they claim S11 mag <-40dB
A Keysight load, with a better specification, would cost less, and would
actually meet its specification.
That's about the same as the load you have.


The chart in the data sheet actually shows better than -50dB at 1 GHz
That’s “typical”, but I don’t believe much from Pastercrap.


https://www.pasternack.com/images/ProductPDF/PE5TR1001.pdf
My company could supply decent loads, but I would need to charge nearly
twice what a NanoVNA would cost.
<https://www.pasternack.com/images/ProductPDF/PE5TR1001.pdf>

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