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From: Leif M

Are any these able to show close sidebands. Like what happens with 1kHz or 100Hz SSB modulation
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The minimum receiver bandwidth range is currently 2 MHz, but the Pluto can be used very successfully as a narrow-band receiver so I think this is just a programming limitation at the moment. You could buy the programmer (that's NOT me) a beer or two via PayPal along with with request for narrower receiver spans!

Cheers,
David
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

I have discovered that this happens and everyone tells you the problem has
been solved. But when you try all the fixes, it still does not work! It
seems that the WIN10 virtual comport gets confused by having made many
changes. I don't know exactly why, but I found a site that has a "driver
fixer" and that worked for me.

Here is a link:


Please let me know if this solves your problem too!

Robert M.

Thanks, Dragan - clearly seen on the web page!

Parts ordered...

Dave

Recommended capacity and dimensions are listed on tindie page.

On Tue, 10 Mar 2020 at 01:59, David Feldman <[email protected]>
wrote:

Please excuse this post if it's been covered previously, but with a
nanovna-v2 enroute via tindie, I realized I believe it is not fitted with a
battery by default. Is the battery specification (part number or dimension,
anda any specific additional requirements) available?

Thanks,

73 Dave WB0GAZ wb0gaz@...
(originator of nanovna-users on groups.io, so with precious little time
then left to actually play with the thing!)

On Sun, Mar 8, 2020 at 08:00 AM, Kerr Smith wrote:

Using my NanoVNA I want to measure the impedance (and return loss / VSWR) of
my RF input circuit so I can adjust the windings to get a good match but the
NanoVNA outputs around -13 to -9 dBm, this is too high for the NE602 RF input
which has a maximum input of about -25dBm.

How would I go about attaching the NanoVNA to the RF input of the NE602
without causing an overload?

The NanoVNA output with older firmware is around the levels you posted. With Hugen's latest firmware it goes up to 0 dBm.

Let's assume you are using the older firmware and you want to get a test level lower than -13 dBm. There is a technique you can use to reduce the level being input to the Device Under Test (DUT). What you need is a good 20 dB SMA attenuator like the ones posted below. Connect a short SMA cable to CH0 of the NanoVNA and the other end to the input of the attenuator. Then set your frequency range to the band of interest (like 6 to 8 MHz for your 40M tests). Go into the Cal menu and do a Reset to clear all the cal parameters. Then do a calibration in the normal way placing the short, open and load on the output of the attenuator. When you have finished save to one of the memory locations (1-4).

Now you have calibrated with the attenuator in place and you can measure Return Loss and VSWR by setting your Traces accusingly. The maximum signal into the device, in this case your impedance transformer, will now be -29 to -33 dBm. This "trick" has some inaccuracies compared to the no attenuator method but I find it works well with a VSWR from 1 to 4. It works even better with 10 dB of attenuation but much worse with 30 dB.

Disclaimer: This is not my discovery. I found this technique posted by someone else on this group several months ago. Maybe they will follow up this post with their comments...

Please excuse this post if it's been covered previously, but with a nanovna-v2 enroute via tindie, I realized I believe it is not fitted with a battery by default. Is the battery specification (part number or dimension, anda any specific additional requirements) available?

Thanks,

73 Dave WB0GAZ wb0gaz@...
(originator of nanovna-users on groups.io, so with precious little time then left to actually play with the thing!)

All nanovna-h sold by us have version number marks on the PCB. Since rev3.4, we have also added version number marks on the shell labels.

hugen

In case it matters - version 0.4.0-2-g7c2f745
No version marking on any of the PCBs as far as I can see (I took off the front and back covers).

Kerr,

I have wound these high ratio transformers using FT50-43 and FT37-43 toroids and always found leakage inductance which affected VSWR, Bandwidth and Insertion Loss. I then read about W8JI's experience with BN73-202 and BN43-202 binocular cores. You get better coupling with these and less leakage inductance. The initial permeability (2500) of the BN73-202 is so high that you only need a few turns to meet the minimum 4X reactance at the lowest frequency. So for a balanced input with a 3000-50 ohm match 1 turn on the primary and 8 turns on the secondary would work well @ 7 MHz. The 73 type material has low resistivity so I recommend that you use kevlar wirewrap wire or Cat5/6 insulated wire becasue enamel wire might nick and contact the core.

Hi all,
I bought a new NanoVNA-H on ebay and received it today. It seems to work, but when I connect it to a laptop using the supplied USB-A to USB-C cable, I get a warning "USB device not recognised. The last USB device you connected to this computer malfunctioned and Windows does not recognise it". I've tried connecting many times, different ports, rebooting, and a different laptop, but always get that message and the device shows up as "not working" in device manager.

I had a quick look at the board, the connections to the socket and soldering of the processor look OK, no shorts that I can see.

Has this been seen before, is there a solution or do I need to buy another one?

Thanks for any advice.

Hi David,

Do you have some information about the maximum dynamic range the pluto can
do in sa/tg mode?




Le dim. 8 mars 2020 à 07:43, David J Taylor via Groups.Io <david-taylor=
[email protected]> a écrit :

For those of you with an ADALM Pluto SDR, here's a 70 MHz - 6 GHz spectrum
analyser & tracking generator:



Looks very interesting. Anyone played with this software?

Cheers,
David
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

Ground loop due to residual inductance.

EMRFD has a detailed example of what that is and how it can degrade a filter.

Experimental Methods for RF Design, ARRL press.

Allison
-----------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

Any idea when it is available at Ebay. I am lazy and would not want to open one more account to somewhere.

Are any these able to show close sidebands. Like what happens with 1kHz or 100Hz SSB modulation

Thanks for the book page image - this is essentially what I have currently breadboarded up although my toroids are wound for 1.5k rather than 3k. I am going to try removing a turn off the primary side and adding a turn on the secondary side initially as this will give me a 50 to 3k ohm match (well 50 to 2938 ohm).

The other difference is that the output transformer in the image uses an FT-50B-43 and I am using an FT37-43 for both input and output transformers as these are the ones I have plenty of.

Once I have made a few measurements I will then wind new toroids using the Wes Hayward numbers and see how they compare, this should be a 50 to 3828 ohm match. It will be interesting to see what difference the two windings make to the return loss / VSWR and output.

Thanks again for this suggestion.

Kerr,

Wes Hayward (W7ZOI) did some tests on the NE602 (lower temp range than SA602) and published them in his book Experimental Methods in RF Design. The balance input configuration will give you better performance. Here is an excerpt from his book showing the test results and how to wind the transformers....

ground loop or pcb residual capacitance?

I put it online in pdf because that can be read/viewed by anyone.
The pptx format is not compatible with e.g. OpenOffice, and the file is also quite large.

If you want the original pptx file, no problem, send me a mail on my qrz.com email address.
(This also gives me some feedback about who is interested or using my work, hi)

If you want to make a translation into your language, please post it here, so that maybe you can collaborate with others on it.
(and hopefully agree on the fact if the Return Loss is negative or positive ... hi)

73 - Luc ON7DQ

...maybe.

Since last I posted, I've experimented with a variety of possibilities; none of which worked...8^(

But, I reverted back to a message where I mentioned building a filter with half of the circuit on each side of a common copper substrate that didn't have the anomaly.

That construction gave me the idea that maybe there was a ground loop; I'd read about that sort of thing but not for HF. Anyway, I reworked one of the LPF PCBs to put all the RF ground connections on one common plane. Via's were added to connect the planes physically otherwise. The attachment shows an ExpressPCB model.

This corrected the effects for 20m, don't know about 30 yet.



--
Chuck, W5USJ

On Mon, Mar 9, 2020 at 07:31 AM, <mcebokli@...> wrote:

"... I have the cables and standards from the old one, so no problem there."
=================================================================

Marko,
The RG-174 cables and SOL standards delivered with the original NanoVNA are only rated up to 1 GHz. If you intend to use the V2 (SSA-2) to its full 3 GHz capability then you should consider the cost of adding 3 GHz rated cables and standards, in addition to the 3.7V battery.

If you only intend to use SAA-2 at your desktop connected to a PC then a battery is not needed. For portable use I believe either a 3.7V Lion or LiPo battery can be installed. A battery from an unused cellphone would probably work fine.

- Herb