will do - thanks

Specially for RFI hunting this hack may be very usefull:?https://tinysa.org/wiki/pmwiki.php?n=Main.LNA
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Jim,
I feel the pain of noise as well. I have noise sources that are well into my IC-9700 at 1296 here, and I'm out in the countryside by a good distance. One would think the area would be RF quiet but, with the occasional use of welders on nearby farms, electric fences, older power lines and transformers, a neighbors solar panels, another neighbors wind generator, not to mention the cell tower with apparently a large amount of LTE data on it in the field down the road and the surprise FM Broadcast tower a few short miles up the road it's noisier than I had hoped when we moved out here.

The FM station I only just discovered so close because it is the first thing I found when I turned on my Tiny SA for the very first time just 2 nights ago.? I too am in the process of sweeping the house and area for noise and find this little device amazing.

You are going to find a lot of weird stuff.? I once found a band blanking noise source in my kitchen late at night that was a total eye opener. A major appliance that had a single LED that led me to find it - our dishwasher. The heating element had an indicator LED as to when it was active. That heating element took me out totally on more than one band and took me about 6 months to figure out walking around with a small radio. This thing would have been so much faster. Intermittent use of the dishwasher made that even harder mind you.

Also, in my current house I have an LCD TV that makes far more noise when off (yes, when OFF) than when on.? I suspect a mostly unloaded PS is doing that. Anyway, best of luck in your hunting. Watch your steps when sweeping. Too wide a step and you may miss a narrow source totally.

Sean

On Fri, Jul 30, 2021 at 06:03 PM, Jim Dawdy wrote:

I would like to be able to do a more accurate and sensitive survey for stronger RFI sources in my home and neighborhood.? What settings would be good to plug into the SA so that I can get a bit more granular reading of RFI sources, identifying the worst offenders?

Hi Jim,

A lot depends on the type of noise source and it's location.

For 'sniffing' emissions from stuff in the home, such as power supplies, chargers and other assorted domestic electronics, where you can get right next to the item. A small antenna such as a short whip (E-Field probe) or 1" screened loop (H-Field probe) is usually good enough to identify the worst offenders. The noise level will increase dramatically, when you place the antenna alongside the offending item, so it's relatively easy to check though a room in just a few minutes.

In this instance I tend to use a relatively large bandwidth of 100KHz or larger, and a sweep width of 0-50MHz, in order to keep the sweep speed reasonably high, whilst being able to observe the most problematic part of the spectrum in one go, but this does mean that the overall sensitivity is reduced. When doing this, beware that any conductive material will act as an antenna, so it's quite normal to find that the noise source may increase in strength (along with SW broadcast signals) due to re-radiation from the conductor, when you bring your 'sniffer' antenna close to them.

When walking around the neighbourhood, trying to locate distant noise sources, I use a different tactic. In these cases it's usually better to concentrate on a specific frequency where you know the noise to be present, and use a narrower RBW and sweep width, so that you don't get confused by other interference and signal sources, that may not be what you are trying to find.

You will also need to use an antenna with some gain and directivity, as the TinySA isn't quite sensitive enough to be able to pick out weaker signals that you can hear on you main radio. Setting one trace to maximum hold is also handy, so that you can compare if you have passed the source and then determine if you are getting closer or further way from it.

I've successfully used a small tuned loop with a 50cm (20") diameter in conjunction with the TinySA to triangulate and locate noise from roof mounted solar panel optimisers, whilst walking around at street level.

There is a plan for a simple QRP tuned loop towards the bottom of this web page.



One other useful tool when interference hunting, is to implement the audio output modification on your TinySA. It's a lot easier to be able to listen and identify the interference whilst walking around rather than having to keep your eye on the screen all of the time, especially in bright sunlight.?



/g/tinysa/message/4045

Good hunting,

Martin

This video is for people that are more familiar with the tinySA and how it can be connected to a computer and how the tinySA can be controlled via the computer.

For new users? its best to follow the "tinySA first use" video:?
That will show a far easier way to do power calibration of the low input.

Here is the full list of video's


--

Spiff72:

I decided to attach the -3db attenuators as 'savers', since they seem most likely to be used?

Thank you,

Chris, KJ7BLE

This is from the example "Calibrating the low output level". The first part talks about setting up a 30MHz, -25 dBm signal and seeing it with a scope at the HIGH INPUT after setting CAL OUTPUT to 30 MHz. I thought the? high output/input was for above 350 MHz signals!? So why are we looking for a 30 MHz signal at the high port? Then we do a similar setting for the low output port and compare the levels for calibration.? In the example the signal level has to be corrected by -1.5dBm. So now we are supposed to? connect a USB cable and enter

leveloffset low output -1.5
saveconfig 1234

to calibrate the low output cal signal

Somehow the user has to? have a program running to enter these commands, and all I can see to do this is have a USB serial monitoring program installed.? A little more info here would be a great help.
syd/wt1v

To answer the question from Christopher about the foam, I think this would be roughly equivalent to the foam I used for the upper case:


The above should be a 5-pack of 12" x 8" x 1/8" thick neoprene rubber closed cell foam - MAKE SURE it is the 1/8" thick option.? This is WAY more than would be needed, but it could have uses elsewhere, I suppose.? Reviews seem to indicate that some of the thicker options (1/2", for example) are a bit less than the nominal values stated on the product page.

The sheet material I used under the tinySA (lower case) is probably equivalent to this:


The above is a pack of 10 pieces of roughly 8" x 10" 1mm sheets.? From the reviews, it looks like this is not "grippy", but it doesn't really need to be.? I put the bottom rubber-like sheet in mine for cushioning more than for grip.? Really just about any 1mm thick material could work for the lower case application.

The power went out in my neighborhood yesterday after an early morning storm.? I got up and out of curiosity, hooked up my FTDX-1200 to the battery I keep handy for just such occasions.? I wondered what the noise levels would be like, and lo and behold, noise levels on every band were between S0 and S1, except for 80m,, which as expected was an S5.

With the power back on, the only band that's close to S1 is 30m.? All other bands are S4-5 with 15m being almost S8.? If I wander around with my tinySA and the telescoping antenna, the baseline noise level, without any adjustments to the default settings other than scanning the HF band, is about -95 to -80db across the bands.? If I put the antenna close (within a few inches) to something like a computer or fan, it drops down to maybe -70db, which i would pretty much expect..

I would like to be able to do a more accurate and sensitive survey for stronger RFI sources in my home and neighborhood.? What settings would be good to plug into the SA so that I can get a bit more granular reading of RFI sources, identifying the worst offenders?? In other words, to maybe discern an RFI source that's REALLY contributing to the S5 levels, as opposed to an RFI source that contributes only minimally.? I.e. to identify the worst offenders,? but those which are still not massively obvious +10dB RFI sources (which, thankfully, I don't seem to have).

I had thought to construct a simple HF loop antenna for DF such as the one here:?? to use.

Any thoughts are appreciated: I have hardly taken my tinySA out of the box, so I'm quite unfamiliar with it.

Jim
KQ9I

UPDATE:? The Thingiverse page looks like it has updated now.? I had to clear by browser cache for it to show correctly.

I have updated my Thingiverse page to DELETE the old STL files and STP assembly files, and uploaded the new versions (filenames include 073021a as a datestamp).? This may time to update correctly (that site is pretty flakey sometimes), so please give it a while before you try to download them, and confirm that timestamp is in the names first!? Here is the thingiverse link again:??

To avoid complicating the Thingiverse listing with the new "narrow footprint" option, I am going to attach the files for that version to this post for now.? If someone prints it successfully and can confirm that it works - specifically the fit of the cables in the left side compartment - please let me know, and I will create a "Remix" for the case on thingiverse for the narrow footprint option.

Again - the size of this one is 135mm wide by 120mm front to back.? The height did not change.? All the instructions and comments on the thingiverse page should still apply (settings, post printing, etc).? The ZIP file contains STLs for each part (lower case, upper case (foam), upper case (nofoam), and STP files for the assemblies (foam and no foam).

Thanks

开云体育

Ahh okay thanks Andrew. That makes sense now.? I've only had my SA for a day now, so still learning the ropes.

No. As I understand it, lowercase indicates automatic mode; uppercase
indicates that you've made a manual change to the setting.

Andrew, KI5HYC.

开云体育

Awesome thanks Barry!? Can I assume that uppercase means the given setting is ON, and lowercase is OFF?

Nice!? I see you have some longer SMA connector savers (I assume that's what they are).? Those look longer than the ones I accounted for.? Do you have a similar attenuator in there that you can check to see if it fits in those slots (at least the left one) and still lets the lid close?? As I mentioned above, I caught an error in the upper case that may prevent the lid from closing on those.? I just fixed my models and will add new STL files to my thingiverse page in just a bit.? I also increased the height of the space beneath the "bridge" that supports the tops of the attenuators in the hope that it will provide room for both cables, even when they are stacked on top of each other.? My original only had enough height for one cable, so they had to nest side by side (or one bend inside the other bend).

Mine didn't have an issue because I printed it prior to making the adjustment for the connector savers.

If you have support material under that bridge between the connectors, you can remove it and the cables should tuck into the space under it so they only need one bend - that might not have been obvious from my earlier photos.

Finally, here is a screen grab of a smaller footprint option for those with a smaller printer bed.? This one is 135mm wide and 120mm front-to-back (plus about 10mm for the hinges).? It sacrifices some space in that left compartment , and I am not 100% sure that the cables will still fit, but I think they should (especially with the change in the clearance under the bridge).

I honestly don't know where I got the foam - it was something I had on hand - I may have grabbed it from work a long time ago.? I will do some googling and see if I can get an idea of what it is.? The backer was labeled "3M Bumpon".

There is an alternate model with protrusions for that upper case that may be used without foam, or possibly with a very thin rubber or foam pad, but if you choose to print that - WAIT until I upload the new versions with the correction to that attenuator hold-down feature!? They will be named with today's date (072021a).? You would want the one with NOFOAM in the title.

I printed it in blue PETG, and it looks and fits great! Thank you!

?

Where do you get your self adhesive foam that is in your pictures?

?

Thank you again,

Chris, KJ7BLE

Is this the example where the frequency or level of the cal output is measured?

If so this is the explanation:
The high connector is used for both the high input/output, the cal output and the LO output when using the LO output option for creating an tracking generator.
When measuring the frequency or level of the cal output very accurately you do not want any other signal leaking to the high connector possibly disturbing the cal output
This is done by setting the tinySA in high input mode effectively shutting down the biggest part of the circuitry that could cause leakage to the high connector while the cal output is still being generated as the cal output is created be a separate circuit.


--

It seems that I had forgotten to adjust those little scallops in the upper housing after I made the adjustment to accommodate the SMA connector savers.

Forgot the image for the above comment...

Oops - I was just looking at the assembly to see if I could shrink it without too much work (I can), but I noticed an interference between the attenuators and the feature in the upper case that is supposed to hold them in place when it is closed.? See image.?

I will fix this and upload new versions of the upper case shortly.? Mine was printed with this error, and it still closed, so the actual amount of interference is probably less than what is shown, but it still should be fixed.

I will also be sharing some images of a narrower version later...

Stay tuned.