Stephen Tompsett wrote:
Kristinn Andersen, TF3KX wrote:
Hi - I am looking for an impedance analyzer. Primarily for antenna
measurements (only 1,8-30 MHz) and secondarily for misc. lab
measurements (L,C,Q measurements, signal generation, etc.). The
possibilities I have been looking at are (in no particular order,
prices approximate):
a) MFJ-259B ($300)
b) MFJ-269 ($220)
c) AEA VIA ($600)
d) Autek VA1 ($200)
d) Micro908 kit from AmQRP ($210)
e) N2PK Vector Network Analyzer project ($150)
At first glance I have the following points/questions:
- Does MFJ-269 offer anything over 259B in addition to VHF/UHF?
- W8WWV tests (web) don't indicate that AEA VIA performs better than
the MFJs.
- Micro908 is new. Any experiences, comments on impedance accuracy?
- N2PK may be the most accurate(?) but needs a PC and involved
construction.
- Any comments on the Autek?
All suggestions are appreciated, based on experience and technical
quality.
73s de Kristinn, TF3KX
I have used three of these
MFJ-259B - OK while it was working, but it has failed twice. I do
not recommend!
Autek VA1 - Nice - but fiddley to use build quality not good
eats batteries!
AEA VIA - Very nice, the display makes on-site adjustments and checks
easy, ability to store and transfer data to a PC is useful
Solid build - won't run off NICAD/NIMH - it needs 12V!
N.B. I find the third party PC software better than the
official AEA software
At the time I attempted to review the AEA-CIA a few years ago, my worry
was with the built-in firmware, which produced weird results in R-X mode
(like, physically impossible).
The difference between the "amateur" and "professional" leagues for
impedance measurement is that the professional Vector Network Analysers
use a calibration procedure to compensate for their own internal errors.
This boosts the measurement accuracy into a completely different league.
Of all the ones mentioned, only the N2PK and the TAPR designs can do
this. All the others really are playing in the amateur league.
--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek