Powernumpty

I posted this to the UKQRM group.
Turns out this specific issue and charger type was mentioned in RadCom (RSGB magazine) a few months back.
The actual issue is that the manufacturers are leaving off the mains filter components.
They are still being sold on Amazon.

Would not an OV per minute with logging or max hold be better than relying on the the visual indicator?

Always good to hear it worked in the end!

That Beagelbone voltage dip thing has caught a lot of people but the general power management and control has probably saved more hardware and installs than we will ever know.

I can still vividly remember the shockof discovering I had not managed to kill my Kiwi with serious over voltage. I corrected the voltage it just went on without holding a grudge. It's that sort of event that reminds me there are still some things available that have been engineered not just built.

Why is it not good?

I know feeding 5.3V to the Kiwi sounds a bit agricultural but I have unintentionally fed much more than that into the Kiwi (not Beaglebone direct) over an extended period without issue.
Unless you are going to use sense wires in production I'd tweak the supply up to that. A good few of those who post on the forum set the supply above ~5.2V to reduce the chances of issues caused by brown out as described in the quick start. There is DC filtering and traces before it gets passed to the BeagleBone.

Power the lambda on, tweak to 5.2-5.3V, connect only one Kiwi, report back.

Thursday I noticed my WPSR results and spot ranking had tanked, I check a receiver and there was an almighty level of QRM, checked the noise charts and spotted that it started at around 8:15 the previous evening (Wednesday).
I rotated the Wellbrook loop but it was already nulling in roughly the right direction so the signal was large. Here is a screen dump from a CB vertical.



As I have been through this many times here I often feel like just giving up and finding another hobby but after a few misserable hours I figured use the S Meter extension and gather evidence.
All through Thursday, Friday and today really bad though different patern to the first day or so.
Checked after running for nearly eight hours today and it had gone off!



By now I had taken the Wellbrook on an extension coax to a number of points so that I could identify it was coming from one particular house (who I have only spoken to once when they moved in).
Despite previous wasted time approaching neighbours about this sort of problem I knocked on the door, they were great.
Turns out it is a cheap battery charger (£18) in a shed being used to charge, and desulphate by pulse, a lead acid vehicle battery.

Don't buy this charger type please, if you see them kill them with fire and bury them at least ten feet deep.
Foxsur!



I said I'd try to sort him some filters for tests and lend him another charger but I might just give him my half decent branded one made back when compliance was a thing, can't face this level of junk again.

One for Rob (no follow up needed),
Checking my Grafana plots, 40m together with 60m were virtually a straight line, all the others looked normal.

Long story short I had a -1000dBm/1Hz recorded at the same time on those two bands so the "Auto" scale was doing it's best to keep everything in view.
1:36AM was the exact moment we had a fairly local, singular, lightning discharge.
I am somewhat impressed that it caught it, equally disturbed that all my Kit was connected to the antennas at the time.

Stu

Hi Tom,
Quite interesting idea to have a "follow" feature, would probably need the users permission (or a pop up "user x wants to follow") or it gets a bit creepy.
Yeah, "stalker mode enabled...".

I've seen people on my SDR and wondered what they were looking for.
Stu

Project needs a "Thermal Cape"
I've ordered some bits as my scrap box only has a couple of heat pipes and both need a lot of work, would get round the space issue though.
This is just waiting for some themally conductive double sided tape plus a pad for the PMIC and a bit more inspiration on physically retaining at the network end.

The ML-30 has an impedance mismatch that means there is a noise spike around 5MHz with the supplied loop, DSL creates loads around 15MHz so phone lines are an issue.
That said for a balcony install your noise level is better than many. I don't think mine 7m from the house had that few interfering signals.

I would try another BiasTee - feed the voltage to the loop through that. The supplied BiasTee has a 5V-12V step up which does create noise. I used mine with an unregulated "6v 600ma" Linear from a DECT phone, that gives about 10V at the load presented by the ML-30. You could see a bit more noise generally but also some wanted signals may come up throught the noise.

Also buy Ferrite beads, large sizes (11-13mm) wind all your in-home cables through those a few times while watching the waterfall. I did that unitl I could not longer see a difference.
Concentrate on VDSL/ADSL lines and any switchmode supplies.

I aslo found that a large FT240 size ring on the coax (as many turns as possible) realy helped, they are expensive but really do sink the QRM.

73 Stu

It would be interesting to test both the ethernet cable and the supply to the Nano router with a few turns through ferrite.

This is a remarkable difference so I assume the Kiwi is also physicaly very close to the antenna?
If the setup is that sensitive it is probably also seeing other, less obvious noise.

I tend to purchase clip on ferrite for 11-13mm cable then add those to any cables around the Kiwi and close to the antenna.
Pass as many turns through the ferrite as will physically fit. Run the waterfall a little slower and make sure there is a decent bit of "before" prior to any changes.
One advantage of the Kiwi is that the user can have a phone right beside the cable or item under test.
I also leave another device on at the same time with the full span waterfall at half speed, I check that later to confirm any improvement.

I spent far too long doing that but it does mean now that my setup is reasonably resilient in a noise prone location (terraced houses).