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Hi Dave,
no, not really. What I meant saying: I never needed to recalibrate the AA-600 between ham bands. That's(And that is exactly on the topic (NanoVNA and Antennascope software working well together:) The RigExpert is calibrated at it's N connector plane, once and (almost) forever but nowhere else. That is the only cal plane I need. Calibration with a huge number of cal points (I don't know the exact number at present, though) covers the full 600 MHz range at close enough spacing. So no recal is needed, except for aging reasons, perhaps. A practical example: I measured my antenna (i.e. a narrow banded W3DZZ on 80m) at the rig side coax cable end in the shack. The RigExpert Antennascope (1.0 and 2.0) software permits saving that in an .s1p file that I can use in SimSmith, that allowed me to obtain the exact feedpoint .s1p (sweep impedance) data file. No need to: 1. leave the shack for terminating the coax at the (hard to reach) antenna feedpoint, 2. go back to the shack and calibrate the RigExpert for that (one-antenna-unique) cable length feedpoint plane, 3. go back to the feedpoint and reconnect the antenna, 4. go back to the shack to obtain the feedpoint impedance sweep data. Instead, with that easily measured and calculated feedpoint sweep impedance file I could cut my cable length and use an LC tuner such that I now have much better than before, and now also flat, SWR across 3.5 ... 3.8 MHz without retuning. A big improvement. This could also have been done with the NanoVNA - but for o n e b a n d o n l y because of the small number of 101 only cal points. After recal for any next band, the same procedure would have been needed again with the NanoVNA. Instead: On the AA-600, all calibration is (almost) once only: 1. for all frequencies 1 ... 600 MHz 2. at the RigExpert's N connector plane. No other plane is needed. That is why that calibration can stay for all my needs on all (in my case below 30 MHz) bands. There is no need to recalibrate the RigExpert - except for aging reasons. The manufacturer's cal can stay in many practical ham cases for all uses. Probably to start with, that is better that what many can calibrate. Needless to say, that in my (below 30 MHz) case the N socket's precision is not of major concern. It's ruggedness, however, is. Neither my MFJ-259 nor my NanoVNA has such rugged, long lasting connection. This is why I love my AA-600 most of my three analyzers. 73, Hans DJ7BA -----Urspr¨¹ngliche Nachricht----- Von: [email protected] <[email protected]> Im Auftrag von Dr. David Kirkby, Kirkby Microwave Ltd Gesendet: Freitag, 12. Juni 2020 19:25 An: [email protected] Betreff: Re: [nanovna-users] RigExpert's PC software now Supports NanoVNA and is Open Source #applications #consolecommands #measurement On Fri, 12 Jun 2020 at 17:48, DJ7BA <dj7ba@...> wrote:
You can not avoid the need to calibrate virtually any VNA (RigExpert, NanoVNA, Keysight etc) if you wish to measure the actual complex impedance of an antenna because the impedance is changed dramatically by the connecting cable. If you only measure at the cable in the shack, then you are not getting as much information as you can. It is only being used like an SWR meter. Dave. -- Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@... Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom -- Diese E-Mail wurde von Avast Antivirus-Software auf Viren gepr¨¹ft. |
