It can't hurt to try. I wish I had bought a cal kit when I purchased my FA-VA5, but most of my measurements are at HF, so I convinced myself that the basic 50 ohm load was good enough.

Have you considered building a few calibration loads, just for a 'sanity check'? I used a BNC-to-SMA adapter, but you can also use a BNC panel mount...



I've been pleased with the unit's performance measuring components at HF. From my perspective, it's more intuitive than a nanoVNA. Now I want to turn my hand to measuring crystal ESR or Q, as some filters I've put together for my NC-40A projects are very odd...

Hi Wes,

scalar SWR against scalar SWR. Should be the same, shouldn't it?

The entire mess started when I tried to safe presets and the VA5 lost every setting and I had to do a factory reset.? If I will not find a solution this thing will end up in the scrap. As sad as it sounds...

Edit: when it was working at least better a couple of month ago, it sometimes hang up during calibration of the load. This was really a pain in the ass thing because when you're out in the field and you are screening a large area of some MHZ (a multiband dipole im my case) and the VA5 hangs up after 10min of waiting time for SOL calibration and you have to start over again...my mood-S-Meter loses the first db of happiness...?

vy 73, Peer?
?

Hmm, the manual says for the Amphenol CAL Kit -41,66ps for S and -113,52ps for O. Now I'm a but confused. I mean I will try your values, perhaps they will solve my problem mentioned in the other thread.

vy 73, Peer

Peer,

I think you mean that the indicated SWR is lowest at 7060 kHz.? That is not necessarily the resonant frequency (X=0).

The FA-VA5 is probably giving you the correct answer.? How you are determining SWR?? Regardless, everything measures > 1:1.

Wes? N7WS

Roger - in the interim, you could manually add SOL data. Should work ok for 30MHz and down as long as you aren't measuring xtal filters or anything exotic...

Open delay: -99 ps
Short delay: -284 ps
Load: R = 50
L = 4.9 nH
C = 0 fF
delay = -151 ps.

vy 73 de va3rr

...therefore I asked Jan G5BB with the hope that he reads occasionally in this forum.?

Hi,

you need to have the whole code for the calibration kit. Example für my kit:

This will download the B005_4_SMD_STE_FGG.zip file. I assume that this code is only printed on the original data sheet.

73
Marco

Hi Marco,

found that link, but doesn't work for my code. Thats why I'm asking ;)

73

cal kit data manual download link:

?

https://www.sdr-kits.net/index.php?route=calkitmodel/download&f=B007................................

?

automatic download code:

?

B007.............

Hi folks,

my FA-VA5 is driving me nuts. My Gap Antenna eg. is resonant with a SWV of 1.1 at 7060khz. My VA5 says its resonant at 7243khz. I tried several resets, master calibration with 2 different cal sets, calibration of the frequency range in use. Did I miss something? This phenomen happens at every band of the Gap. Right know, my VA5 is unusable :(

Best 73,
Peer, DL8YF

Hi Jan,

I'm in the same situation. I lost my printout for the Cal Set B103_9. A chance to help me?

Best 73,
Peer, DL8YF

开云体育

Got mine from SDR? kits as well.

Excellent device, you will soon get to grips with the menu system.
The icing on the cake is its compatibility with the DG5SAQ VNWA software.
You will then have a versatile single port VNA.

Keith
G4MIU

I've had my FA-VA5 for a year or so. Best VNA I've had with a great price point.? The three buttons give simplicity to use once you've read the manual and it's robust enough to take into the field. I've had a Nanovna, and? a Metrovna 250 and the FA-VA5 beats both of these in ease of use.

I'll jump on the bandwagon to say that I use my FA-V5 more than my nanoVNA-H4. I used it just this week to compare 'relative' Q at 7MHz of various of some moulded inductors for a Norcal NC40A that I am building.

In fact, there was a S2P "inductor challenge" on the groups.io VNWA group, and the FA-VA5 did ok on some frequencies.

I have found the VA-5 to be an excellent choice. I have owned it for about 2 years.

True, the 3-button interface may not be the fastest way to change settings, but after experiencing an initial learning curve, I find myself remembering the menu structure and changing settings without much effort. That is true even when I have not used it for a few months.

Some would prefer an encoder - but there are downsides to a component with moving parts and a shaft which sticks up out of the device. The button arrangement makes for a smaller overall size, easily packed for travel without suffering damage. Touch screens are interesting gimmicks as well, but they are fraught with many practical issues.

Bottom line, I would say ‘simple and durable is best’, especially for a device which is often used in the field.

--
73 de Gary, AF8A
Cleveland, Ohio, USA

Hi Frank,

I own a FA-VA5 and I am more than satisfied with its performance. It is very accurate when carefully calibrated.

Admittdedly, the 3-button user interface was slightly frustrating when I started to use it but I quickly learned to live with it. It is not a real problem. However, a rotary knob (encoder) and a button or two would have been better in my opinion. Anyway, don't let this stop you from buying it. FA-VA5 is a very good and solid instrument with impressive performance/price ratio.

I don't know about the warranty, ask your dealer.

73 Johan SM6LKM


Frank wrote:

I got mine from SDR kits with the case and additional calibration lements

Very happy as I wanted the sweep function and the swr adjustment tone

and covers a wide range and cheaper than a Rig Expert
--
John VE3IPS

Hello Gary

Yes, lead inductance creates a positive reactance in series with the negative capacitor reactance. The "effective" measured capacitance is then necessarily larger than the capacitor's capacitance and this larger effective capacitance is frequency dependent.

Xc_eff = Xl - Xc

and

C_eff = 1 / ( 2 x PI x f x Xc_eff)

So, if you notice a change in measured capacitance when you change the frequency of the FA-VA5, then this is because of your lead inductances. Towards lower frequencies you get closer to the actual capacitor's capacitance. The lead inductance can be measured by disconnecting the capacitor and connecting the leads together, keeping the leads in the same or similar shape as when they were connected to the capacitor.?
You can measure your loop inductance at different frequencies with the FA-VA5. It will also vary with frequency because of its large size which gives it the character of an end-shorted transmission line to some extent. Your 3.5m loop is not a "lumped element" because it is not very small compared to the wavelength.

73
Dieter, VK3FFB

Dieter - Would it be correct to state that we will have a similar experience measuring capacitance, due to the small value of inductance which is present in the capacitor leads, body etc.?

I ask because I am about to test some air-dielectric variable capacitors. I need to know their minimum and maximum capacitance. The goal is to build a receiving loop antenna (~3.5m circumference) and I expect that I will need somewhere between 20 and 200pf to tune it to resonance.

--
73 de Gary, AF8A
Cleveland, Ohio, USA