Jeff:
Was really great to see you yesterday at BreezeShooters! Hope to see
you again soon, maybe better yet, chat on the air!
73,
Jim
[email protected]
On 6/2/2014 6:11 PM, [email protected] wrote:
To the learned audience:
I agree that the 8410 is an excellent place to start to learn about VNA
architecture and issues. I, as well, learned the HP 8410, first as manual
system, then we did the automation ourselves (Westinghouse was too cheap to
buy a "bundled" system) using a 9825 desktop calculator, from the HP app note
of "Semi-automated Network Analysis". My education in this regard was
superb! My industrious Vietnamese grad student is learning the issues from my
8410 books and he is building a more modern version.
However, a slight clarification about the early VNA's: They were not YIG
based, that came later. The classic HP8542A system was a BWO based system
with the 8690 Sweeper and a bunch of plug-in drawers that worked with a Signal
Multiplexer to yield a 1-18 GHz system. A 5100 based synthesizer was used
to lock the harmonic converter to eliminate harmonic "skip" cal errors
(Brooke alluded to this) and the whole mess was driven by an HP 1000
mini-computer and had a reel to reel tape drive for mass storage! It was huge
( a
three bay rack) and cost $250K in 1968 money (a lot today, $1.5 M ??). I had
one of these systems and still have parts of it! I automated my own newer
8410 system in 1986 when I started my consulting company and used the 12
term error model software pak (HP11863??) in RM Basic on a 9826 computer (big
step up!). While I do not recommend this approach for anyone today, the old
literature provides great insight into the issues, where the errors come
from and so on, as HP had figured all this stuff out. It is a shame that
shipping to Europe is so high, as a lot of these systems and components are
still around (I have six 8410 systems still !). A mainframe is under $50.00
and I bought a working 8411A converter for $20.00 at Dayton this year (dont
ask why, I guess it was too cheap....).
I had just about every variant of this stuff, VLF through 40 GHz. Man,
HP engineering was tops in those days!
Still, I think a very dedicated homebrewer could build his own design for a
< 3GHz VNA from adapted "wireless" parts, but I am too lazy for that. I
much prefer hacking some proven hardware into what I need.
73
Jeff Kruth
In a message dated 6/2/2014 5:47:17 P.M. Eastern Daylight Time,
[email protected] writes:
Message: 7
Date: Mon, 02 Jun 2014 14:36:09 -0700
From: "Richard (Rick) Karlquist" <[email protected]>
To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] VNA design
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 6/2/2014 12:41 PM, Brooke Clarke wrote:
Hi:
I started with the HP 8410 and added an external computer.
Since it can be used manually I think it's an excellent way to learn
about VNAs.
http://www.prc68.com/I/MWTE.shtml#NA
For my last 8 years at Agilent before retiring in March, I
was doing advanced R&D on network analyzers. The newer
guys coming up didn't have an intuitive understanding of
network analyzer architectures like I did. I
started using the 8410 back in 1973 before I even worked
for HP. Because of the modular design, it was like a
teaching tool that forced you to understand what was
going on. When I mentored the young guys, I would
explain to them a lot of principles based on the 8410.
Modern network analyzers are too "automatic".
The 8410 puts modern VNA's into perspective. BTW, I used
to sit next to Dick Lee, who was a member of the 8410
design team in 1963 at the dawn of the golden age of
microwave instruments based on YIG tuned oscillators
and step recovery diode samplers.
As you noted, the architecture was built around the YIG tuned oscillator
and certain things were done that way they were because of that.
Rick Karlquist N6RK
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
---
This email is free from viruses and malware because avast! Antivirus protection
is active.
http://www.avast.com
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
