If this 6ghz VNA also functions as a spectrum analyzer with tracking generator,
that makes it worth twice as much to me.
Perhaps have a stuffing option to use an external bridge as previously mentioned by Jim Lux.
An external resistive bridge should have a BOM cost dominated by the SMA's.
No need to have the external/internal bridge selection be jumper selected on the main board
if that compromises performance, the external bridge is cheap to build.
Then sell a variety of bridges as accessories.
Perhaps one with an attenuator and booster amp for Jim.
Could there be an external "bridge" with a V/I type sensor, and thus able to measure
a wider range of impedances in the device under test?
But the important thing is to get something done and working as a VNA
with something like the specs cited. Don't let me slow this down.
Extra features can come with the the next version out,
and then we will all buy yet another VNA.
Jerry, KE7ER
toggle quoted message
Show quoted text
On Tue, Oct 6, 2020 at 02:13 AM, Hugen wrote:
Yes, using binary data transfer, USB-CDC is no problem at all. But this is a
completely restarted project. Jan developed this project completely
independently. We can consider compatibility in the future process, but please
don't put any pressure on Jan now. Although the APP currently provided by Jan
is not perfect, it works very well and already includes simple spectrum
analyzer and signal generator functions. It can also be manually configured
and firmware upgraded, which is a very good innovation and experiment.
On Tue, Sep 29, 2020 at 09:59 AM, Jim Lux wrote:
On 9/29/20 9:27 AM, Jerry Gaffke via groups.io wrote:
I would think attenuators and booster amps may as well be in the external
cables.
Not terribly familiar with all this, perhaps there are special tricks
involved to measure
something like s12 on an amp?
Oohh. that's everyone's first guess.. but think about it.. if you want to
measure the S11 of a LNA, you can't put 50dB of attenuation in front of it.
You put 50 dB of attenuation in the stimulus line, then the bridge, then 50dB
of amplifier in the receiver line. Then calibrate as per usual. If your
receiver has good dynamic range, you don't need as much amplifier.
Adding them to a $300 VNA board adds complication and sources of trouble.
Modular is good when it comes to seldom needed features.
True - maybe a different version of the board, that just leaves out the
resistive bridge. And some extra SMA connectors
The ability to use a different bridge would be interesting.
Perhaps lay out the board such that one could insert vertical SMA's
and stir some surface mount parts to accommodate this?
Yet another product variant for Hugen to sell at some time in the future.
But I suspect most nanovna users have never felt the need for an external
bridge.
Requiring an external bridge for all work with the VNA is perhaps a bridge
too far
towards modularity.
Typically, the way it's done is to have two connectors with a removable jumper
between them.
I would venture that for most VNAs that have this, the jumpers have never been
removed except when doing factory cal/re-cal. Or when someone sets the VNA
down on a non-smooth surface and breaks the jumper.
Jerry, KE7ER
On Tue, Sep 29, 2020 at 08:47 AM, Jim Lux wrote:
yes, it's going towards the fieldfox type of capability, not the "bench
VNA" -
The latter would typically bring out the source and receiver inputs with a
loop, so you could use different bridge or insert attenuation to make it
easier to test amplifiers.
This design has a 30dB sep attenuator, but still, if you're testing a LNA
with
a maximum input of -70 dBm (because it's designed to receive signals at
-150
dBm) this probably isn't your box of choice. Assuming he's putting +10
into
the attenuator, the output power will be -20 dBm or around there. That's
enough to saturate a lot of LNAs.
Likewise, if you were testing a 10W PA, you might want a booster amplifier
in
the drive on port 1, and an attenuator in port 2.
