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RF, Microwave, HAM Radio / Re: PocketVNA Any idea what its like?
« Last post by hendorog on Today at 02:58:32 pm »
 :horse:
I found a good site explaining that technique with the attenuator.. Might be interesting for others:
https://www.evaluationengineering.com/features/0200loss.htm
It also mentions "The technique is not appropriate for S-parameter VNAs because a full 12-term, two-port calibration inherently will produce accurate results." So the issue could be overcome by not using a pad; but doing a 12-term 2port calibration? Maybe that's why it's in the new beta? Hopefully eb4fbz can chime in  :)

12-term calibration can't be done on a T/R vna because the second port does not have a signal source and can't measure reflection.

Both the miniVNA tiny and pocketVNA are of the T/R (transmission/reflection) type.

The full two port version of the xaVNA supports this kind of calibration.

There is a cal type called one path two port which can do this on t/r network analysers. You need to manually reverse the dut.
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RF, Microwave, HAM Radio / Re: EXPLANATION OF THE REGEN RECEIVERS
« Last post by Audioguru on Today at 02:42:08 pm »
Regen and super-regen are used for kids' cheap remote controlled cars today, not for radios.
They were used for radios many years ago when you had only a couple of radio stations in town so the poor selectivity did not cause interference. A regen radio needed you to fiddle with the regen amount control.
The quenching of a super-regen provided automatic regen amount control and was used before FM stereo because of interference from the 19kHz pilot and the 23kHz to 53kHz sidebands.
Morons did not notice the AM clicks and static on a regen FM radio since its sensitivity was seriously reduced by it being tuned to one side of an FM station for "slope detection".
A regen aircraft receiver must not be used in an airplane or near an airport since it causes interference.
A regen or super-regen radio in your home or car might cause interference to neighbours.
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My rules:
1. Wired.  Cut wireless anything to an absolute minimum. Then cut some more.
2. F*ck the Cloud. All personal play and work data must be local and private. No exceptions.
3. No subscription software/IOT services. None. This includes OSs, so excludes Win10.
4. No 'auto-updates.' Disable them all, ditch anything that doesn't allow disabling auto-updates.
5. If you have a choice between a thing that has a CPU, and something that doesn't, pick the latter.
6. Any company that progressively reduces utility of their products, is your enemy. Boycott them absolutely and forever.
    (That includes Apple and Microsoft.)
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Yes I understand that as I have been following this thread for about a year now, I'm just providing information that I think people might find useful.

I purchased the parts to upgrade the computer in my scope about 10 months ago:  AIMB-581 MB and NEC NL10276BC20-04 LCD.  I finally made an LVDS cable for the MB and did the upgrade to Win7 right after my last post here.  I used DXL's modified drivers for Win7 and had no trouble installing X-Stream 5.8.1.1 32-bit.  I don't think it really gains us much over 8.1.0.1 / 8.1.2.0, though.  I think the main additions are for features that our scopes lack the hardware to support like triggering on protocol decode.
5
Let me know if you guys need any help determining thermal stability of the paints you're using.  I have a PerkinElmer TGA in our lab and I'd be happy to run some samples.
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Test Equipment / Re: Hack of Sigllent spectrum analyzer ssa3021X?
« Last post by dazz1 on Today at 02:23:19 pm »
Hi
Currently exploring my SSA30xx. 
I saved some files of scans in the local:/ folder.  Copying these to a USB stick is painful.

Is there a simple way of transferring these by Telnet session or other means?
Where is the local:/ folder?

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I first want to thank the all mighty flying spaghetti monster that Comcast does not operate in our area (although Spectrum isn't all that great either).

If you're using the AP and router that your ISP provides you, don't expect quality, nor anything decent. They are designed to benefit them with low costs, and whatever else they want to throw on.

A cheap straight router and a nice Ubiquiti AP, then you have everything you need for about 150 bucks, and it will be faster, more stable, and likely more secure than what your ISP throws you.

It's the same reason why you should almost never use the locks storage companies give you, as they are probably some cheap 4 pin cheaper than master lock chineese shit.
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Beginners / Re: 12v stable from a 4S5P li-ion pack
« Last post by Audioguru on Today at 02:20:14 pm »
If your battery can supply 20A continuously then each cell provides 4A. It has 4 cells in series so its fully charged voltage is 4 x 4.2V= 16.8V. The poor voltage regulator will heat with (16.8V - 12V) x 20A= 96W. Do you have a voltage regulator powerful enough and a heatsink large enough?
The voltage regulator has a minimum input voltage of about 14V but your battery will drop to 12V. Then when the battery is 14V each cell is 3.5V which is almost only half a discharge.
   
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The presence and importance of the window have been known for a century:

https://en.wikipedia.org/wiki/Infrared_window

Yet another case of "discovering" something old and spinning it for research dosh.
It's not that the infrared window was discovered, it about developing a modern material which makes use of it.
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Wow there is another transgirl here?

IIRC there are many, like a half dozen or so.
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