*** SIGLENT FEATURE REQUEST ***
The new SVA1032X firmware upgrade 3.2.2.6.0R7 upgrade works, BUT...
The field "IF bandwidth" for the VNA is still grayed at 10 kHz and this seriously limits the performance of the instrument.
So, please, if somebody here can contact Siglent, ask them to change this! Even the NanoVNA can configure lower BWs, improving the measurement noise and hence the dynamic range.
Based on the hardware performance in SA mode, the instrument should be able to reach 100 or better 10 Hz BW.
The DANL is specified in the data sheet with -156 dBm/Hz. At 10kHz ENBW, this should result in a noise floor of -116 dBm. Is that so bad?
OTOH, the DANL of the NanoVNA is certainly worse, so a narrower RBW is needed to compensate. However, this does not come for free, but it comes at the cost of a slow sweep.
DANL is specific to the SA mode. In VNA it is much worse: preamp is missing and the bridge introduces a loss in S11 mode.
In VNA it is much worse: preamp is missing and the bridge introduces a loss in S11 mode.
In VNA it is much worse: preamp is missing and the bridge introduces a loss in S11 mode.Show us this with a load and Mag Loss trace.
0dB stimulus should return a ~0dB trace.
In VNA it is much worse: preamp is missing and the bridge introduces a loss in S11 mode.Show us this with a load and Mag Loss trace.
0dB stimulus should return a ~0dB trace.
The question is, what's the S21 noise floor when you measure S21 of a "zero-gain DUT" using a stimulus of (say) 0dBm?
(an example of a zero gain DUT is if you terminate port 1 and port 2 with 50R each)
[ And (any) bridge or directional coupler certainly does introduce some additional dynamic range loss for S11 readings, since only a fraction of the signal is coupled to the receiver. ]
Member RoV has no issue with S21 measurements, a through measurement and only makes comment on S11 measurement, a reflection measurement.
I asked for a loaded Mag Loss trace which will show if there is a problem or not.
Member RoV has no issue with S21 measurements, a through measurement and only makes comment on S11 measurement, a reflection measurement.
I asked for a loaded Mag Loss trace which will show if there is a problem or not.
I mentioned S11 because it tends to be more noisy due to the additional loss introduced by the internal bridge. S21 doesn't use the bridge, because the analyzer is a T/R, not a full 2-port, so in S21 mode is equivalent to the SA in tracking mode (however, in VNA mode it misses the BW setting respect to SA mode).
If you measure a load you will find S11=0 with some noise. If you look at it in Log Mag mode, you'll see a noise level around -something (perhaps -50 dB?). Decreasing the BW, this would improve.
This is particularly critical if some device is inserted. For example, when measuring an external antenna impedance, in order to avoid the risk of damaging the VNA due to external signals, I prefer to insert a limiter in series to the port (full limit @5-10 dBm), followed by a 10 dB attenuator . Then I calibrate AFTER those devices. In this way the VNA port is very well protected, but >20 dB attenuation are added to the measurements (the chain limiter+attenuator is passed twice, first by the test signal and then by the reflected one), so traces tend to be very noisy (even during calibration) unless BW is kept small. This procedure worked very well with an old hp 8714ES, but doesn't with the SVA1032X.
Average safe reverse power Total : 30 dBm (1 W)
Maximum safe reverse level Voltage: ±50 VDC
How any ordinary antenna we might sweep might exceed these levels is unclear.
Average safe reverse power Total : 30 dBm (1 W)
Maximum safe reverse level Voltage: ±50 VDC
How any ordinary antenna we might sweep might exceed these levels is unclear.
Antenna measurement was just an example.
I don't think the 30 dBm rating applies to port 1. It does, for a brief time and -I believe- with at least 20 dB internal attenuation inserted, for port 2 (SA port).
Average safe reverse power Total : 30 dBm (1 W)
Maximum safe reverse level Voltage: ±50 VDC
How any ordinary antenna we might sweep might exceed these levels is unclear.
Antenna measurement was just an example.
I don't think the 30 dBm rating applies to port 1.
It does, for a brief time and -I believe- with at least 20 dB internal attenuation inserted, for port 2 (SA port).
When having longer antennas, eg. 40+ meter you get to certain times quite impressives levels. Especially when ROV is starting to transmit nearby - or somebody else e.g. in a car.
To that comes - and that is more important for magnitudes - a static charging of the Antenna and coax cable to several hundreds of Volts, which generates enormous HF-Spikes when the max Voltage of the insulation at a certain point in the structure is reached and an arc will occur.
This is not hypothetical - it's a matter of fact. I had a ground plane Antenna, which was not having an inductor to ground on the roof - for 2m only - I measured nearly a 1000v during a rain shower with an electron tube multimeter (ancient) .
I have seen cases where the input and power transistors of transceivers were killed by the peaks produced by static arcs.
From the User manual preface:
Electrostatic Prevention
Operate the instrument in an electrostatic discharge protective area environment to avoid damages
induced by static discharge. Always ground both the internal and external conductors of the cable to
release static before connecting.
From the User manual preface:
Electrostatic Prevention
Operate the instrument in an electrostatic discharge protective area environment to avoid damages
induced by static discharge. Always ground both the internal and external conductors of the cable to
release static before connecting.
but one time grounding does not help if the capacitors (coax line) are re-charged. I would never use port 1 or 2 of the VNA without external protection with an Antenna mounted outside.
Understood however I have never used such practices for S11 antenna measurements of which I have done many.
Hi...
I am still missing a spectrum analyzer for home, but I also want to be able to measure the overtagunsfunktion of filters, so I will probably need the combi device from siglent:
https://www.batronix.com/versand/spektrumanalysator/Siglent-SVA1015X-VNA.html
Are there any reservations about this device ?
I had skimmed the manual earlier, the VNA section.
If I have interpreted correctly, the start frequency is at 10Mhz ?
That would be high, if one wants to represent e.g. the transmission line of a 10Mhz filter.