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Other Equipment & Products / Re: Any opinions on the AiXun T3A?
« Last post by Ungolian on Today at 08:03:11 pm »
This looks like a winner.  Assuming it really is 200w (manufacturers have been known to overstate specs), you get better performance than the KSGER, better display, easier FW updates with USB port, sexier casing, supports 245 handle out of the box...  It's a hard upgrade to the KSGER.  Plus it's roughly the same price as a KSGER+245 handle+3 tips.  The tips are probably garbage, but having a few junk tips on hand isn't always a bad thing.  The board quality may be an issue, but most people on here should have no problem fixing a few joints.  Is it possible to get the power board out too?  Is it hot glued in or something?
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One more graph:



Doesn't have any more information as the rc-frs from above, but looks nice ;)
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Somebody else PM-ed about a MEMS microphone, too, https://www.digikey.com/en/products/detail/pui-audio-inc/AMM-3742-T-WP-R/14289962 with very good response around 50kHz and above, indeed, but I don't think I have any analog MEMS based mikes.

Might be a few MEMS mikes through the scraped parts boxes, but AFAIK those were with digital output only, and not sure if their sampling rate would be high enough to record at 50kHz or more.  Never tested any of those digital MEMS microphones.  Should look for some analog MEMS microphones, but not sure if I have any.

Tested today some miniature speakers and the piezo discs from singing post cards.  Nothing promising so far.  The speakers doesn't play well at more than a few kHz, and the piezo disks have some strong resonance peak at approx. 7kHz and multiples, but above 30kHz couldn't get any signal with them.   ???

Searching the scrap boxes for electret microphones now.  Would search for any MEMS mikes, too.
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Metrology / Re: Keysight (lack of) calibration & other services
« Last post by rf-messkopf on Today at 08:00:25 pm »
I will contact the mentioned email address to get my Gloris account back working, and I'll report here about the outcome.

My Gloris account is working again. Thank you R&S for resolving this quickly.
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Who wanted a LCD 'scope?
www.ebay.co.uk/itm/203537268248?

Dang... 100 quid...? Even I would buy that just to see what makes it tick...

mnem
 :popcorn:


Bugger, has that been pulled? or was it ending tonight & I just missed it?
The redesigned ePay bidding page doesn't give a start date anymore.  :bullshit:

David
Ended on schedule no bids.
Looks OK to me seller is a house clearence type
Watch for relist.
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Beginners / Re: Analog versus digital oscilloscopes 2
« Last post by TheUnnamedNewbie on Today at 07:55:11 pm »
WRONG - your perception is that chinese instruments aren't dominating in the entry-level market?  ok, just google "best oscilloscopes", LOL.

I'm not even going to try to respond to the rest of your incoherent ramblings, but the whole point of what I said is that there has been an 'entry level' market for oscilloscopes and other test equipment for a very long time and none of the players in that market have gone on to become an A-brand leader.  The A-brands don't really compete in this area and they never have.  Where did I say that Chinese instruments weren't dominating the current entry-level market?  I'm well aware that they are and I don't think that gives them a clear path to join HPAK/Tek/R&S/LeCroy anytime soon.  "Making hundreds of millions"--where do you get your facts?

I'm with you on this one. Our lab keeps buying some of the Rigol and siglent entry level equipment now and then, and every time we get one, and then decided that it's just inferior to the ones by the A brands and nobody uses it. None of the big labs I've gone to used anything but the big names (Keysight, R&S, Tek, Yokogawa, Anritsu...).

It's all about service. The fact that we regularly get asked by R&S to provide questions we have which they will then have their engineers put into a presentation and come explain us. The fact that Keysight sent a applications engineer when we struggeled with their equalization software package, free of charge, within a week.
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FPGA / Re: FPGA VGA Controller for 8-bit computer
« Last post by BrianHG on Today at 07:54:39 pm »
You can try a Diodes inc mosfet 'DMN53D0LQ' in place of the 3904 as it's turn on is ~20ns, but it's turn off + fall is also around 30ns instead of having that 10x hold time of 200ns.

NXPs NX138AK mosfet is also good and it's also completely on on when the gate-source reaches 3v.
The NXP mosfet is faster...
But we are talking just over 5ns faster.

However, they are drop-in replacements for the 3904 transistors and you can change the series base resistor to 0-100 ohm for top speed.


Diodes inc 'DMN2230UQ' is also good and there exist a lot of fast mosfets with will turn on really hard at 3v g-s.  Though I think your final solution may be a logic IC with open-drain output so you have a few outputs on 1 device at your disposal.
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Microcontrollers / Re: Why do people not like Microchip?
« Last post by nctnico on Today at 07:53:27 pm »
I have hard time believing that Microchip MCUs have had such quality problems that they just "stop working".

OTOH, it's normal to have very mysterious problems when working with MCUs because these are complex devices with many possible failure modes; not only limited to ESD, reset pin connections and power bypassing, but also some software issues seem to cause something like hardware failure while it really is a software problem! (I always refer to the case where a small bug in I2C initialization code made some 3-4 units out of batch of 30 fail in the init, others work perfectly, appearing like a soldering/ESD issue!)
But you have to ask yourself if you want to use a microcontroller which is so finicky to use. In the end such bugs end up costing time. Time which costs money and delays product introduction which in turn reduces sales. For smaller volume you are better off using microcontrollers which have not been optimised down to the last transistor and which have proper I/O pads. If you look at the Attiny for example: the Vih level of 0.8V has no meaningfull noise margin. This can be problematic in noisy environments. Especially compared to a proper CMOS input which typically has a Vih of 0.7*VCC.
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...Capacitor bodge attached.   



mnem
 >:D

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First 24h measurement with the new frequency difference meter:

First graph: my GPSDO vs. the FRS rubidium (rc-frs)



Second: my GPSDO vs. the TruePosition GPSDO (rc-tp)



Third: the difference of the above - FRS vs. TruePosition (frs-tp)



And the ADEV graph by TimeLab:



1sec ADEV apparently is dominated by FRS noise. Looks my GPSDO is somewhat better in the short term (10s ... 300s), medium term (1000s ... 10000s) the TruePosition wins. Long term should be defined by the FRS, but I can't see the trend yet. Of course, this is somewhat comparing apples to oranges, they have different antennas with different view of the skies.

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