Improperly stored AN/UPM-84 military surplus spectrum analyzer is not having a good time.
It covered 10MHz - 40GHz.
N connector input up to 12GHz, then waveguides up to 40GHz.
It’s just been pointed out to me that the reason Apple runs a trade-in programme for older devices is so they can reduce the size of the used market, and has fuck all to do with recycling.
New thread on my big ongoing embedded project since the other one was getting too big.
To recap, this is a pilot project for a bunch of my future open hardware T&M and networking projects, validating a common platform that a lot of the future stuff is going to run on.
The primary problem it's trying to address is that I have a lot of instrumentation with trigger in/out ports, sometimes at different voltage levels, and I don't always have the same instrument sourcing the trigger every time.
So rather than moving around cables all the time and adding splitters, attenuators, amplifiers, etc. to the trigger signals I decided to make a dedicated device using an old XC7K70T-2FBG484 I had lying around.
Of course, as with any project, there was feature creep.
I'm standardizing on +48V DC for powering all of my future projects as it's high enough to move a lot of power but low enough to be mostly safe to work around live. So I needed to design and validate an intermediate bus converter to bring the 48 down to something like 12 for the rest of the system to use.
The FPGA has four 10G transceiver pairs on it. I used one for 10GbE (not that I need the bandwidth, but I was low on RJ45 ports on this bench and had some free SFP drops) and the rest are hooked up to front panel SMA ports (awaiting cables to go from PCB to panel) to generate PRBSes for instrument deskew.
Since I'm pinning out the transceivers and am planning to build a BERT eventually, I added BERT functionality to the firmware as well (still need to finish a few things but it's mostly usable now).
And since I have transceivers and access to all of the scope triggers, it would be dumb not to build a CDR trigger mode as well. That's in progress.
@gsuberland@manawyrm@DM_Ronin
That seems to often be the suggested paste mask by manufacturers as well.
3x23 or the lesser 2x2 grid instead of on large plate.
It's more or less widely known that especially high-capacitance ceramic capacitors have significantly less capacitance at their rated voltage than at 0V. While this effect is detrimental for bypass applications, has anyone ever turned that effect into something useful?
I was thinking of using this effect to make a variable capacitor for a VCO or maybe getting some use out of the non-exponential RC charge characteristic.
@gsuberland@karotte
Unfortunately I think it is likely too temperature dependent to do that.
But it could be interesting to see.
A 1:47AM thought, could the body diode be used to measure the die temperature?
Then you'd have the built in temperature sensor for temperature compensation as well.
But back to DTC's. So far all of them that I have seen used a pile of switched capacitors.
Or were just ST8P switches with "bring your own capacitors".
What uses would there be for 7638MHz and 7554MHz DRO oscillators?
Not phase locked, so not super stable, don't multiply immediately to any interesting bands either, so not that usable as a marker either.
And these have a negative supply voltage.
Is there such a thing as a cost optimized "discharge-only" RF terminator?
Basically, something that you use for discharging ESD from cables and is built to tight mechanical tolerances on the mating interface so as to not risk damage to expensive connectors, but need not be optimized for good return loss out to mm-wave frequencies etc.