Sunday, 3 May 2015

Fault finding gets into my head.

Fault finding gets into your head.

That was what I was going to say.

But Mrs FVM doesn't get fault finding. Maybe nobody else does. Maybe it is only me who chases round in circles for hours after things.

Not that I find fault with Mrs FVM. Not an exercise worth pursuing. Painful.

No, I mean when the washing machine breaks down I go through this process which she doesn't understand. She is used to me by now.

FVM: "What were you doing when it broke down?"
Mrs FVM: "Washing the clothes"
FVM: "No, what program was it on"
Mss FVM: "The one I use to wash the clothes"
FVM: "No, there are 8 programs, which one"
Mrs FVM "I dunno"
FVM (getting steamed up): "Well, was it a rinse or was it a wash?...  Had the water filled, ... had the pump emptied the remaining water, ... has the water jet thrown the powder into the drum, ... did the drum sound uneven, ... has the fuse blown, ... were the clothes all cold, ... are the room lights still on, ... does the paper shredder still work?
Mrs FVM: The paper shredder? I am trying to wash the clothes and they are all wet.
FVM: Why didn't you say that? You mean the spin cycle is not working?
Mrs FVM: I dunno. Just fix it.

This is married bliss.

By the way the paper shredder is in the same room as the washing machine and shares the same circuit breaker, though they are separately fused. I did not try to explain, though it makes me look like a screwball to have mentioned it.

You see, it was a mistake to ever talk about the paper shredder. To a fault finder it makes sense, but to the rest of the world I seem to have taken leave of my senses, Which is possible. I spend most of my days under the bench with a torch, plugging in and out USB plugs. So much, that I plan to install mains lighting UNDER my desk.

I just cannot help it. If I cannot find a fault I imagine one. I built a diplexer to separate the signal from a dual 50MHz/70MHz antenna into two rigs. It is a vast thing, about four metres by three meters and it lives in the loft above the house. It works by stub co-ax filters so it has to be big. I tested it before applying RF to both ends at the same time. But this nagging doubt arose ... does it attenuate the signal too much. How much is too much - no time to ask, just find out.

Every so often, I ran co-ax up to the roof and ran myself down to the rig. An arrangement of rigs and co-ax switches was not much help as you really need to test it in situ. So I ran up and down the ladder instead. I tested it on the Carrickfergus beacon in GI - 263 km over a tricky path. Is it stronger this way or that way? With the diplexer or not?

I never got a proper answer. The beacon is too variable in strength to know anyway, and the loss would be tiny. This is not fault finding. There is no evidence that there ever was a fault. But I want to find one if there is one. AND NAIL IT FOR GOOD.

Hard to do if it isn't there.

This is more like "fault-causing", and I am good at that too.

So I stopped using the diplexer, just in case.

Even real faults, like computer generated noise due to poor USB connections, are given the same treatment. Have to find them even though they are tiny.

Today it is the regular issue of the USB sockets. The present shack computer is a 4 core AMD processor built into a mini-ATX box. So there are only a few slots for multi-socket USB boards. Outboard USB boards seem to make a lot of noise to be picked up on the rigs.

This PC is on an ASUS board. I have a much better 8 core one on a Gigabite board, but it is full ATX size and does not fit under the bench !!!. The ASUS board USB sockets are so noisy I cannot use them and I have 8 USB3 sockets on plug-in slots on the PC, and an outboard USB3 board to make up the numbers. They are ALL used. I cannot put any more plug-in USBs onto the PC (I've tried !!!) because I need to use a slot for a Sound Blaster audio card to make nice pure WSPR.

So stand by for a messy photo. This is my subsidiary PC display ..
Left to right along the bottom:
WSJT10 on meteor scatter duty on 70.230 (lots of garbage)
WSPR on 6m from the Flex (Power SDR above)
WSPR on 10m from FT-817.
At the top is Spec JT for 4m WSJT10.

And on that Spec JT are two thin lines. Arrrggghhh. USB QRM. Find it Jim.

FIND IT. There are only 11 permutations of USB sockets, two video boards, and a host of devices which might be to blame. Printer, scanner, wi-fi, three rigs, 5 power supplies, 4 fans plus the PC itself. Then there is the work computer, screen, DVD drives, DVD duplicator, ... Easy?

Digging about under the desk I feel pain - the cat has come in and is scratching the top of my bald head, demanding food, just as I try to jiggle the leads and all those ferrites (there are dozens of both). Fault finding is really getting into my head now. I am on my hands and knees and there is no point trying to shoo her away. Easier to go and feed her than have my head ploughed.

Back again in the dark - it is almost all coming from the Flex 1500 USB lead. Bah! Out of my filters drawer comes a REALLY BIG TDK ferrite filter which makes very little difference. Turn the Flex on and off to test a bit more (hence the noise bars on the 6m WSPR). Bah, Cannot stop it.

This was not here yesterday. What have I done? Oh yes, I unplugged all the USBs to stop another noise and then plugged them all into different sockets. Which stopped that noise, but  ...

And so it goes on. Plug in USB, unplug USB. Chase the noise. Find the fault. Get it stopped.

Not this time.

At what age do slightly overweight men with Celtic genes die of heart attacks?

Really, as young as that?




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