- Original NanoVNA a waste of money
Re: Original NanoVNA a waste of money
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THe SAA-2 is very different
On Sunday, 21 March 2021, 16:41:35 GMT, Andy G4JNT <andy.g4jnt@...> wrote:
I've had a DG8SAQ VWNA for a long time, now, which in terms of performance, quality of software, display capability and user interface knocks spots off these Chinese things. Its a really professional quality bit of kit and would normally be the only one I'd ever use. In use, it's as nice to use as the HP ones I used to use at work - just doesn't go nearly as high in frequency :-(
But it needs a PC attached, so when out in the garden or up a mast (!) a small self contained one has more than a few advantages.
These Chinese Mini VNWAs are a blatant rip-off of the DG8SAQ, that uses exactly the same hardware, NE602/612 mixers that conveniently have a differential input so perfect for taking the output from a resistive bridge right down to DC.
On Sun, 21 Mar 2021 at 16:27, G8DQX list <list@...
the block diagram and circuit (schematic) diagram are at https://github.com/ttrftech/NanoVNA/blob/master/doc/nanovna-blockdiagram.png.
What brings the machine alive, though, is the firmware, which has
had considerable development over time.
There are occasional reports on the nanoVNA list (https://groups.io/g/nanovna-users)
of touch screens failing due to cases fouling the surface. The
usual solution seems to be to add washers or shims. One also has a
vague recollection of solder splashes being a problem.
HTH, 73, Stay Safe,
On 21/03/2021 13:04, Andy G4JNT wrote:
removed front ang back covers, and it started to - sort of -
work. The touch screen is a total failure, but I can drive it
using the manual button thing. replaced the covers and it
stayed working. SO I'm guessing an intermittent in a ribbon
cable link on the touchscreen.
has been saved from the sledgehammer for now.
took the opportunity to look inside, including lifting the
covers over the RF portion. Pretty boring; three NE602 mixer
chips, something that is obviously a soundcard type interface
chip and one that is probably an Si family synth - although
the number was a bit meaningless.
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