<azonenberg>
So I got the SMPM bullet puller tool the other day
<azonenberg>
it's expensive but it works *perfectly*
<azonenberg>
and does exactly what it should
<azonenberg>
I'm going to try to design my probes to not require the end user have one
<azonenberg>
by using full detent and smooth bore connectors in such a way that the bullets should in theory remain attached all the time
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<Degi>
What is a bullet here?
<azonenberg>
Degi: SMPM connectors are normally made in the male configuration only
<azonenberg>
which is to say, a shell with a pin in the middle
<azonenberg>
to mate two of them, you place a little pill-shaped coupler between them with two female ends
<azonenberg>
called a bullet
<Degi>
Ah yes
<azonenberg>
And removing them without damage is hard
<azonenberg>
There's basically two options
<Degi>
Yeah, it looks quite intricate
<azonenberg>
the first is grabbing the bullet with pliers about the center line
<azonenberg>
but they're normally rounded enough that the pliers are likely to slip
<azonenberg>
which results in pinching the contacts at the end
<Degi>
yes...
<azonenberg>
in my early testing, i had about a 50% survival rate for bullets removed this way
<Degi>
oh
<azonenberg>
half the time the pliers slipped, the rest of the time it worked :p
<Degi>
welp
<azonenberg>
anyway the second option is a dedicated puller tool which inserts a conical tip into the open end of the connector
<Degi>
Even if it worked, didnt it get deformed a little?
<azonenberg>
No, because i was grabbing the solid body between the open "leaves"
<azonenberg>
then a larger cylindrical shell slides over the outside
<Degi>
ah yes
<azonenberg>
so it's providing a clean pulling motion down the axis of the connector, no pinching of the body, and no way for it to slide
<azonenberg>
They work perfectly, they just cost like $300 because it's such a specialized tool
<Degi>
So basically it jams the outer pins between an outer cylinder and an inner cone?
<azonenberg>
Yeah
<azonenberg>
the two parts are spring attached together like a LA micro clip
<azonenberg>
so you squeeze the plunger to open and release to close
<Degi>
Neat
<azonenberg>
anyway, SMPM male connectors come in two varieties
<azonenberg>
"smooth bore" and "full detent"
<azonenberg>
the latter having much higher unmating force
<azonenberg>
my intent is to design the differential probes with a mix of smooth and full detent connectors such that the bullets always stay attached to the FD connectors, which can be treated as if they were just female connectors
<azonenberg>
and thus an end user won't ever need a bullet puller
<Degi>
Neat
<azonenberg>
For prototyping though, i need one because I need to be able to mate a test adapter to it for connecting to the VNA etc
<azonenberg>
and that has a female connector too
<azonenberg>
so i have to add and remove bullets
<d1b2>
<theorbtwo> I always wonder how hard it would be to 3d print or otherwise manufacture such things cheaply at the location of need ... and almost always come to the conclusion that it would be very hard.
<Degi>
What is some jtag cable that works fine on linux?
<d1b2>
<zyp> anything ftdi-based?
<azonenberg>
Yeah i mostly use either my own homebrewed ones or digilent HS1/HS2
<azonenberg>
theorbtwo: 3D printing lacks the mechanical strength
<azonenberg>
it would be straightforward to make on a lathe probably
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<bvernoux>
azonenberg, hello I'm tempted to buy a LibreVNA to check the performance
<bvernoux>
latest update even add harmonic mixing to go up to 8GHz(with performance decreased ...)
<bvernoux>
The only things I'm not too happy with LibreVNA is the Dynamic range after 3GHz ...
<azonenberg>
interesting. not familiar with it
<bvernoux>
it is less than -60dBm
<bvernoux>
anyway up to 3.5GHz (calibrated) it is more than -100dBm
<bvernoux>
I do not know if the version sold on Aliexpress have same performance ...
<bvernoux>
like we can see Dynamic range is lower than -50dBm near 6GHz ...
<bvernoux>
-60dBm in fact ...
<bvernoux>
it is -70dBm in fact as on right it is Phase in ° ;)
<bvernoux>
so it is not so bad but to be on par with my HP VNA or even PicoScope VNA it will be nice to have -90dBm or -100dBm up to 6GHz+ (with more linear dynamic range)
<bvernoux>
What is nice is the software App for LibreVNA is very nice and there is SCPI commands ...
<bvernoux>
and it is ultra fast Full S2P 10kpoints in less than 1s !!
<bvernoux>
when my HP VNA requires more than 40s(using raw calibrated data) for 1601pts full S2P...
<bvernoux>
something nice for a Pro VNA will be to have native Ethernet as there is only USB today to drive it
<azonenberg>
Yeah
<bvernoux>
So far my major issue with my HP VNA is it is quite slow and limited to max 6GHz and very loud and doing a SOLT calibration is clearly a long process (limited by memory too as I cannot store more than 6 Full S2P calibration)
<miek>
as a workaround you could do the correction offline with scikit-rf
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<_whitenotifier-3>
[scopehal] azonenberg opened issue #419: SPI flash: add support for 4-byte addressing - https://git.io/JOKhP
<_whitenotifier-3>
[scopehal] azonenberg labeled issue #419: SPI flash: add support for 4-byte addressing - https://git.io/JOKhP
<bvernoux>
miek, all is already integrated in PC LibreVNA tools
<bvernoux>
miek, it also support de-embedding which is nice ...
<_whitenotifier-3>
[scopehal] azonenberg opened issue #420: eSPI: implement "Put Virtual Wire" packet type - https://git.io/JO6fJ