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[Ham-Antennas] FIXTURE for XMSN MEASUREMENATS 2.0
I can't give you numbers of improvement as I didn't record those. But I
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can give you the order of additions. 1) Lengthened the shield between the ports. It was originally only the width of the main board. supporting the BNCs. 2) Playing with a thin sheet of double sided board, I added the additional orthogonal shields. I was going to enclose each port except for the lond ends, but in "playing" with the essentially scalar network analyzer, I discovered I gained just as much by shielding opposite sides of each port. 3) That looked pretty good, but again playing with just a piece of AWG #18 stripped solid copper wire, I discovered the added wires on each side of the alligator clips really bought me a lot. And, yes, I believe your analysis that the wires form a transmission line which electrically looks much like a trough line but allows access to the clips. 4) From there, I could make minor improvements in isolation, but all those severely limited physical access to the alligator clips. The additional improvements traded off against physical access was clear I'd stop where I was. The 70 dB (somewhat +) isolation between ports was quite satisfactory for me. I could dig deeper into the noise by increasing the output of the source port on the 8753C, but, again, any additional physical components would limit access to the clips. So I stopped with what you see. Now I gotta wonder how high in frequency it maintains the isolation and good RF performance. Maybe tomorrow? I have too many projects lined up in retirement. It's the satisfaction and joy of having good RF test equipment in retirement! Dave - W?LEV On Tue, May 20, 2025 at 8:06?PM Michael Carter <Mike.Carter@...> wrote:
Hi Dave (W0LEV), -- *Dave - W?LEV* --
Dave - W?LEV |
Having the 8753C is a privilege of once having worked for HP. As you may
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know, HP (before Carly - the wicked witch of the west) encouraged dumpster dipping. There were two of these in the dumpster. I chose the one with all the adaptors in place. All the cal kits were also there. So....... the rest is history. My interests end when one has to involve waveguide. Dave - W?LEV On Wed, May 21, 2025 at 12:03?AM Michael Carter <Mike.Carter@...> wrote:
Thanks, Dave - the incremental improvements are less critical than the-- *Dave - W?LEV* --
Dave - W?LEV |
finding anything like that in the dumpster. I am envious. I worked with Lab Grade VNA since 1979 and continued until I retired in 2001. I received a nanoVNA for Christmas 2024.
having a VNA which fits in my pocket and I can take anywhere I choose is amazing. I feel so spoiled now being able to test my antennas with a nanoVNA any time I choose. I can see the results of my calculations come to life one the screen on the VNA. Reminds me of college where the theory we studied in the morning was exercised in live applications in the afternoon. |
I see another person who asks themselves where did I ever find time to work. Retirement while every day "may" seem like Saturday there are days when it feels more like the first day after after a long weekend and the work is piled so high you can not see any daylight.
"The Golden Years, more like "Fools Gold" at times. "More Work and No Pay." |
But in retirement the work IS play!
My 8753C weighs nearly 100 lbs.! No way is it going to accompany me outside to make measurements of antennas. The NANOVNA certainly can and does go outside to make measurements. Further, the 8753C can not make direct measurements of my long doublet fed with open wire line as it is connected to the power grid and house wiring. The NANOVNA is small enough to make those measurements in the shack with nothing between it and the NANO. I just hope and pray that it will continue to be available to amateurs, professionals, and the schools in the future. It's indispensable for anything associated with RF! Dave - W?LEV <> Virus-free.www.avg.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> On Wed, May 21, 2025 at 5:11?PM VE6LX via groups.io <dclarke2= [email protected]> wrote: I see another person who asks themselves where did I ever find time to-- *Dave - W?LEV* -- Dave - W?LEV |
Thank you Dave for your experimentation with this little VNA wonderbox. I am discovering what it can do. So far it has enabled me to avoid frustrations with some uhf antennas I am playing with. Retirement is indeed busier than when I was employed in the Bell System.
-- 73 de W8NSI Jim New NanoVNA User, please be patient. I build my own antennas and need this. When Tyranny becomes Law, Revolution becomes Duty! |
Well I have a varied Career in Broadcasting from floor Technician to RF Engineer in Transmitters, AM, FM and TV 5 Watt relays to 50 KW base stations.
Then I went on to Telus a Telcom was involved it cellular Antennas and RF Systems.professionally the VNA was indispensable. Now in Amateur radio it is an affordable tool giving incredible results. I may have to invest in a Tiny SA next. Chip technology has made so many thing almost common place. Enjoy your retirement I know I am. 73 Dave VE6LX |
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