<bvernoux>
Attenuation figure of merit: 0.2 dB/inch/GHz, for a lossy channel, 0.1 dB/inch/GHz for a low loss channel.
<miek>
how much loss is too much for a cal standard? i know that ideally open/short standards should maximise the reflection for best results, but i don't know how important it is
<azonenberg>
miek: no idea. but the loss is not something you can ignore and consider "zero"
<azonenberg>
i would imagine that any delta between the actual and modeled loss of the standard is going to directly translate to measurement error
<Degi>
How much effort would a cal standard be based on air coax lines? Like soldering two coaxial gold plated copper tubes between two coax connectors
<azonenberg>
Degi: basically, its doable and is the way to go if you need ultra high grade accuracy
<azonenberg>
but 99% of the time is more trouble than it's worth
<Degi>
I see, yeah PCBs are much easier to assemble
<bvernoux>
miek, for a cal standard we do not care in fact
<bvernoux>
miek, as we will de-embedded it after as it will be fully caracterized
<bvernoux>
miek, On my side what I want is to use the eCal LibreCAL also as a switch in some case and for that it is important to have something linear from few KHz up to 6GHz (or even later 8GHz)
<bvernoux>
miek, Anyway I have computed in worst case the path loss (depending on trace length+width FR4 properties with ENIG) will be less than 1dB
<bvernoux>
That does not take into account the switch loss
<bvernoux>
So the answer if we will use a better PCB than FR4 with Er 4.6 like OSHPark FR408HR with Er 3.66
<bvernoux>
We will have a gain of maybe 0.3 or 0.4dB max
<miek>
yeah, of course it'll be fully characterised but surely the quality of the standards still matters to some extent
<bvernoux>
So it will be better but clearly who cares about 0.4dB especially as OSHPark PCB you will need to assemble all yourself
<bvernoux>
I have chosen the best possible RF Load already used by @azonenberg
<bvernoux>
So I do not have lot of doubt especially to reach up ton 8GHz easily without any strange things
<bvernoux>
At the end the performance will mainly depends on the switch (if the Impedance of the PCB traces are respected +/-10% with Z=50 Ohms)
<bvernoux>
On my case I will do all at JLCPCB
<bvernoux>
as they will do also the assembly of the 5 units with the components I have bought
<bvernoux>
Anyway I will do all measurements when I receive the boards to check everything and also see the variations over 5 boards
<bvernoux>
It is what is missing on the LibreCAL GitHub as there is no any S2P files
<bvernoux>
or S1P files
<bvernoux>
In my case I will do full 2 ports S2P files with S11/S21/S12/S22
<bvernoux>
with my VNA HP8753D which goes from 30KHz to 6GHz with 1601pts
<bvernoux>
Of course the HP VNA will be fully/freshly calibrated with my expensive Calibration Standard before
<miek>
nice. yeah, i've been following the progress on github but it'll be great to see some measurements
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<bvernoux>
@miek, I have done some measurements on lot of experimentations with stripline/TRL
<bvernoux>
Up to 6GHz which is the limit of my VNA so far
<bvernoux>
With some other stuff I have not pushed but I will finish with the eCal(LibreCAL) as doing so much test will kill my Calibration Standard/VNA Cables(which are very expensive) I have already planned to buy new VNA SMA cables to replace my older ones
<azonenberg>
bvernoux: i've been eyeing some Koaxis cables for VNA applications, if you are interested in trying them out
<azonenberg>
i've used a lot of their other cables and they're excellent
<bvernoux>
it is EMI Gaskets, Sheets, Absorbers & Shielding 80 - 115dB D Shape L-22" Shield Gasket
<bvernoux>
For the LibreCAL
<bvernoux>
I was planning to buy some additional connector saver like that SF-SM50+ but it is out of stock
<azonenberg>
woo good news from lecroy
<azonenberg>
the 4 GHz differential probe i sent in with a suspected bad cable actually had a failed connector
<azonenberg>
which was covered under warranty so they fixed it at no cost
<bvernoux>
ha great !!
<bvernoux>
What was the result with that probe it was totally usable ?
<bvernoux>
unusable
<azonenberg>
So the way LeCroy's WaveLink system works is they have the "platform" which has a bunch of power supplies, dacs, etc
<azonenberg>
to supply power and bias / offset voltages
<azonenberg>
and then the amplifier mates with it
<azonenberg>
One of those power connections was intermittently failing open when you bent the cable a certain way
<bvernoux>
ha yes very bad
<azonenberg>
and the amplifier output would peg at -Vdd because it wasn't getting a positive supply
<bvernoux>
yes can be crazy to debug that
<azonenberg>
it would work as long as you held the cable at exactly the right angle :p
<azonenberg>
but yes was useless for practical work
<azonenberg>
the amplifier was quite old and i was ready to just declare it a write-off as it was an older model and i didnt want to pay for a repair
<azonenberg>
so i sent it in on a "let me know before you fix it" basis
<azonenberg>
turns out while the amplifier was old, the platform was fairly new (from 2020)
<azonenberg>
and under warranty until october of this year
<azonenberg>
So free repair
<azonenberg>
My 16 GHz scope is done and shipping back shortly as well
<azonenberg>
at least, as soon as I pay for the upgrade
<azonenberg>
Which is a bit tricky because i had to cancel the credit card they have on file due to some fraudulent charges recently :p
<azonenberg>
So i'm in the process of sorting all of that out
<bvernoux>
What do you have upgraded on the 16GHz scope ?
<bvernoux>
Upgraded it to >20GHz ;)
<azonenberg>
Swapping the processor board out from the old core2quad running vista to a modern i7 running win10
<azonenberg>
swapping the analog system out from the original 8Zi platform to the newer 8Zi-A which comes with a newer frontend, i think like 30% lower noise
<azonenberg>
replacing the 14 year old touchscreen which would often register touches at the wrong spots
<bvernoux>
ha great
<azonenberg>
and then a few other random odds and ends like a missing screw on the front panel
<bvernoux>
the i17 could maybe run glscopeclient ;)
<azonenberg>
Yes, it definitely could
<azonenberg>
anyway so at some point in the indefinite future I will be sending it back to upgrade to an 8Zi-B, the current platform, but that was too expensive to do right now
<bvernoux>
Main issue I think is there is no GFX card so using HD7000 or similar of the CPU could be a bit limited
<azonenberg>
The big benefit from the base to the -B is that the B can interleave channels to get you 2x 80 Gsps
<bvernoux>
Ha yes clearly amazing feature
<azonenberg>
and then i can also bump max memory from 128 to 256M points (or 512M if interleaving)
<azonenberg>
or bandwidth from 16 to 20, 25, or 30 GHz
<azonenberg>
but i wanted to get it on the current hardware platform before doing any of those upgades
<bvernoux>
I imagine does they have asked if you want to buy software options ;)
<azonenberg>
No they didnt
<bvernoux>
And you told them no I will use glscopeclient ;)
<azonenberg>
if i was buying a new scope maybe, but this was just done through the service department
<azonenberg>
but it's no secret that i use scopehal
<azonenberg>
i've met the service engineer at lecroy who worked on my scope last time i sent it in for repair
<azonenberg>
he knows about scopehal and has actually mentioned it to other customers who were trying to do multi scope sync stuff
<bvernoux>
The items are disposed exactly like periodic table yes ;)
<bvernoux>
Too fun
<azonenberg>
marketing nonsense. but they are nice scopes lol
<bvernoux>
Do you have some option to do eye pattern for SerDes/DDR... on yours ?
<bvernoux>
Just to compare with glscopeclient
<bvernoux>
On an other subject I'm working with some well know security companies to do an HydraDancer ;)
<bvernoux>
All will be opensource and based on WCH CH569
<bvernoux>
It will clearly beat anything which exist in term of price/features
<azonenberg>
yes the SDA comes with eye pattern and such features standard
<bvernoux>
So if anyone are interested to help as there is tons of things to do on embedded side and host side(libusb...)
<azonenberg>
the SDA is basically a bundle of the base WaveMaster scope plus th serdes analysis software package, the CDR trigger board, and increased memory depth
<bvernoux>
ha great as lot of others like Keysight/Tek provide such features not freely and not as standard
<azonenberg>
i mean, if you buy a wavemaster then you have to buy those options
<bvernoux>
ha ok
<azonenberg>
the sda is basically just a package deal for getting them all at once
<azonenberg>
and for some reason it's a new SKU
<bvernoux>
Yes yours was intended to be refurbished with 2 years warranty ?
<azonenberg>
on the 16G scope? there wasnt much of a warranty, i bought it third party
<azonenberg>
i think 30 days
<azonenberg>
i was willing to accept the risk of something expensive going wrong because it was such a huge discount vs a new one
<azonenberg>
even after all of these upgrades and fixes it's going to cost me like half of a new one
<bvernoux>
Yes it is clearly a big deal even if there is some risks