开云体育

Yes.

Typically, this is what SCM (Source Control Management) is all about. A wiki is usually not the first tool of choice for providing SCM, though (I've used a bunch of them over the years for both hardware and software design files). The wiki could be used to *document* the contents of the SCM repository, but then there is the problem of keeping the repository and the wiki in sync, and if they are out of sync, the purpose of the wiki is obviated (the repository is what it is, good, bad or indifferent; if the contents are "broken", then the product is probably broken, but the code in the repository can be "fixed"). So, my thoughts on using a wiki to provide documentation for what is where and what is what for the nanoVNA stuff are mixed. Is something that is out of sync better than nothing? How would one know that they are out of sync? What would be the consequences of relying on information that is out of sync? Do we care? I'd have to cogitate on that a bit.

DaveD


On 7/27/2019 7:50 PM, Dave Daniel via Groups.Io wrote:

David,

Why does the nanoVNA group need one more than most other groups?

I have administered Wikis in the past. The one that I like the most is MediaWiki. MediaWiki is the one used for the TekWiki (w140.com) wiki.

Maintaining a wiki, particularly one edited by a group of people, can be challenging.

DaveD


On 7/27/2019 1:26 PM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:

groups.io supports the creation of wikis. I think it would be useful to
have one, with different pages allocated to different topics - a user
manual, instructions to build from source, bugs, etc.

I don't have much experience of wikis. I have thought of setting one up for
the HP/Agilent/Keysight group I am owner of, but have not done so. I think
the NanoVNA needs one more than most others.

David,

Why does the nanoVNA group need one more than most other groups?

I have administered Wikis in the past. The one that I like the most is MediaWiki. MediaWiki is the one used for the TekWiki (w140.com) wiki.

Maintaining a wiki, particularly one edited by a group of people, can be challenging.

DaveD


On 7/27/2019 1:26 PM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:

groups.io supports the creation of wikis. I think it would be useful to
have one, with different pages allocated to different topics - a user
manual,? instructions to build from source, bugs, etc.

I don't have much experience of wikis. I have thought of setting one up for
the HP/Agilent/Keysight group I am owner of, but have not done so. I think
the NanoVNA needs one more than most others.

David,

Why does the nanoVNA group need one more than most other groups?

I have administered Wikis in the past. The one that I like the most is MediaWiki. MediaWiki is the one used for the TekWiki (w140.com) wiki.

Maintaining a wiki, particularly one edited by a group of people, can be challenging.

DaveD


On 7/27/2019 1:26 PM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:

groups.io supports the creation of wikis. I think it would be useful to
have one, with different pages allocated to different topics - a user
manual,?? instructions to build from source, bugs, etc.

I don't have much experience of wikis. I have thought of setting one up for
the HP/Agilent/Keysight group I am owner of, but have not done so. I think
the NanoVNA needs one more than most others.

groups.io supports the creation of wikis. I think it would be useful to
have one, with different pages allocated to different topics - a user
manual, instructions to build from source, bugs, etc.

I don't have much experience of wikis. I have thought of setting one up for
the HP/Agilent/Keysight group I am owner of, but have not done so. I think
the NanoVNA needs one more than most others.

On Jul 27, 2019, at 2:00 PM, alan victor <avictor73@...> wrote:

There is one menu structure missing.

All the way to the top right. TRACE 0...TRACE 3.

Selecting any one of those leads to MENU:

OFF
SINGLE
BACK

Thanks, Alan

Hi Mike. Sure, I understand. Measurement of a 50 dB pad, at -50 dB is fine
business. I would set the display reference position so that the 0 dB
insertion loss line is at the VERY TOP of the display. There are 8
horizontal grid lines, so select ref position to 0008 puts you at the top
in log mag display. Hence, the bottom of the display is at -80 dB below the
top, if we set 10 dB/div.

At HF frequencies, say 10 MHz, I can sweep a 10 MHz filter and given
enough selectivity, at 1 MHz for example that sweep attenuation is down 8
divisions or -80 dB below the center pass band response. If you bring such
a filter data set into the PC program, it appears the data set is in fact
better than that! And I have seen nearly 90 dB down on one of my filters.
So at low frequency, this box is good for a least 80 dB dynamic range. As
we approach 900 MHz, things get a bit worse. The best dynamic range I have
seen at this point is 40 dB. I suspect, if you were to read your 50 dB pad
up at 900 MHz, it would not show 50 dB of attenuation. Now, the query will
be, is the PAD crappy... at nearly 1 GHz... or am I limited by the range of
my instrument?

Alan

________________________________
From: [email protected] <[email protected]> on behalf of Mike
Brown <mbmail@...>
Sent: Saturday, July 27, 2019 4:43 PM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] Semi-bad clone - port isolation

Hi Alan, thanks for that.

Maybe I'm misunderstanding what is meant by 'measurement limit' or have
some other issue but aside from glitches at 300 and 600 I am seeing 50dB of
attenuators measuring -50dB, ±1dB or so, on the logmag scale all the way up
to 780MHz. It is within ±2dB up to 800MHz. (The spec seems to say 40dB
dynamic range in the 600-900 MHz band.)

There's a residual calibration error of about ?dB as the test leads without
attenuators show a small but fairly level loss all the way to 900 MHz.

Surprisingly still no visible effect from a metal plate placed directly
behind the device.

Best regards

Mike


On Sat, 27 Jul 2019, 15:54 alan victor, <avictor73@...> wrote:

Mike,

My measurements below 30 MHz on the black case unit show 80 dB. The limit
at 900 MHz is 40 dB.

This black unit has brass shields cut and formed in the guard ring area.
Although they are kissing the SMA connectors the shields are not soldered
to the connector body.

Alan

________________________________
From: [email protected] <[email protected]> on behalf of

Mike

Brown <mbmail@...>
Sent: Saturday, July 27, 2019 1:35 PM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] Semi-bad clone - port isolation

Hi Roger

Just measured 50dB of attenuators between ports with a range of 1.5 to 30
MHz and it was flat but with 0.05dB of fluctuation due to noise. Upped it
to 60dB with a similar result but about 0.8 dB fluctuation. Placing the

VNA

on a metal surface made no difference in either case.

I assume the isolation calibration is helping but wonder if a complex
impedance might be more challenging.

TBH I was intending to buy some copper tape to solder on but decided to

buy

a better made Nano and keep this one for playing around with. Might still
be worth a go once the other one arrives.

Mike



On Sat, 27 Jul 2019, 13:39 Roger Henderson, <hendorog@...> wrote:

Hi Mike,
No problem :)

Just solder a bit of conductive tape for a shield - i.e. copper tape -

onto

the exposed grounds you have on the board. Should do the same job :)

I am not sure what difference it will make if any. In the low range my
unshielded unit is perfectly adequate. In the high range its not much

chop

at all. <= Scientific terms used freely here.
I think the bridge layout may be the bigger issue, and possibly the
components used.

I also wonder what the effect of adding a common mode choke would be on

the

differential mixer input after the bridge.

Cheers,
Roger

On Sat, 27 Jul 2019 at 23:51, Mike Brown <mbmail@...> wrote:

Hi Roger

Thanks for that - I obviously hadn't experimented enough! Bit of a

nuisance

only having a 4-trace manual.

I have just successfully measured a 6dB sma attenuator at 6dB via

both

ports. The lack of screening will obviously be a problem for serious
measurements though.

Regards

Mike




On Sat, 27 Jul 2019, 11:29 Roger Henderson, <hendorog@...>

wrote:

Hi Mike,
It is not correct that the two trace analyzer will only use CH0.
You can choose which channel to use for each trace.

I have a white gecko branded device which only has two trace

firmware

loaded, and I haven't bothered to update it. So I am sure what I

say

is

correct.

Please feel free to reply if you can't figure it out and I'll

upload

some

screen shots.

Cheers,
Roger

On Sat, 27 Jul 2019 at 22:19, Mike Brown <mbmail@...> wrote:

In case anyone is interested I took some photos while I had my

NanoVNA

apart to solder the sma sockets to the back of the PCB. Rather

than

clog

the forum up they're here:

As noted before this clone has no screening on Ch0 & Ch1 circuits

and

the

panels are both plastic. It came configured as a 2-trace Antenna

Analyser

so the lack of screening may not be too critical as Ch1 is not

used.

The

battery is stuck down with a sticky pad and is slightly too close

to

Ch1

circuitry.

The case is this one:

Mike

-----Original Message-----
From: [email protected] [mailto:[email protected]]

On

Behalf

Of Mike Brown via Groups.Io
Sent: 27 July 2019 09:48
To: [email protected]
Subject: Re: [nanovna-users] Case for black VNA

Just got my calipers out in case a few measurements would be

helpful.

My

sma sockets are as best I can measure, 33.3 mm apart. PCB/panels

86.5mm x

54.65mm. Total height, including slight bulge in plastic rear due

to

battery attached with sticky pad, 14.2mm.

I just noticed my sma sockets are only soldered one side of the

pcb

despite

pads on both sides. About to get my soldering iron out!


Mike

On Sat, 27 Jul 2019, 09:11 Mike Brown via Groups.Io, <mbmail=
[email protected]> wrote:

Hi Frank

My semi-bad clone from seller sqcase has USB C. NB it looks

different

to

the one in the listing:

Dimensions seem slightly different to others. I printed a case

designed

for

another black clone. I'm using the same printer as the designer

but

found I

had to increase the size of the case by 0.7pc to get the clone

to

fit.

The

screw holes don't line up with the screws and didn't before

scaling

(fortunately they're not needed as the case is a nice tight

fit).

The SMAs were slightly too close together and the USB slightly

closer

to

the switch so I had to do some filing. Probably partly due to

the

rescaling

but I think the SMAs really are in a slightly different

position.

Mike


On Sat, 27 Jul 2019, 02:52 Frank S, <ka2fwc@...>

wrote:

I was able to get a Black unit to measure to see if the case

is

different. From shat I found, the white one has nylon

standoffs

(of

the

same size) and the black one has brass standoffs (that are a

different

size). This black one has a USB "C" connector, and the switch

is

a

thru

hole mount. It is a little higher than the PCB (as compared

to

the

white

that is flush with the PCB).
Can anyone tell me if all the black units have USB "C" and

what

the

switch looks like?
Thanks trying to make the best fitting cases for these

"toys".

Frank