Albert Kleyn 2021/08/01 09:06
I fully echo the sentiments expressed by Leon, NT8B, Dave... THANK YOU for
your encouragement , support and pearls of real life wisdom ! It is people
like you and several others here in this forum that help steer newbies
like me thru the uncharted NanoVNA swamp. We full well know Dave that you
could have chosen to "Sit by the pool, with the beautiful XYL, a Gin and
Tonic in one hand and a Pina Collada in the other, while looking at the
palm trees and the ocean" !!! Instead, you and a handful of others, are
voluntary here, helping/preventing raw novices like me from sinking
slowly under in the NanoVNA swamp.
It is appreciated much more that this short post can hope to express.
On Sat, 31 Jul 2021 at 21:53, David Eckhardt <firstname.lastname@example.org> wrote:
> It's generally OK to firmly grip the shield side of the connection to make
> a good connection. However, do not get near the center conductor side of
> the fixture. If you are doing differential measurements, do not hold
> either side of the fixture. In measuring differential loss, you are making
> a DM (differential mode) measurement and neither of the connections to/from
> the VNA should be grabbed. When making a CM (Common Mode) loss
> measurement, only one winding need be connected, and you are making CM
> measurement so the coaxial braid side of the fixture side can be grabbed.
> One caution when testing above 30 MHz: Do not use alligator clips or
> banana jacks/plugs. With *GREAT care*, they can be used, but not above
> 150 MHz *AT ALL*!!!
> I'm glad you found my postings useful. I initially made the measurements
> for my own edification because I have the tools. Then I thought I could
> help others by putting it all together. Thanks for the complement!
> If I can't help others in retirement with the knowledge and common sense
> I've gained over some 50 years professionally and in the hobby, it's time
> for my own personal pine box.
> On Wed, Jul 28, 2021 at 9:15 PM Leon - NT8B <email@example.com> wrote:
>> Thank you for creating and sharing these documents. I have been
>> searching for methodology to test the chokes I'm building for use in my
>> radio operations and your documents are very helpful.
>> I have a newbie question relating to the NANO calibration procedure
>> described in the document on CM attenuation measurement: how do you
>> correctly connect the 51-ohm resistor when doing the load measurement step
>> in the calibration? I'm assuming the correct procedure is to attach one
>> end of the resistor to the alligator clip that's connected to the CH0 port
>> of the NANO, and the other end of the resistor is connected to the copper
>> cladding on the test fixture. What is the best way to ensure a good
>> connection between the resistor and the copper surface of the test
>> fixture? Is it OK to hold it on the surface by hand or do you recommend
>> another connection method, like using an alligator clip?
>> Again, with great appreciation and 73,
>> Leon NT8B
> *Dave - WØLEV*
> *Just Let Darwin Work*