Thursday, 28 May 2015

Some dx, but not my greatest radio day.

Actually, yesterday was a pretty awful day.

I had to avoid a car crash with another driver who was going too fast and could not brake in time. I had to decide to take a risk which almost made me crash into a third vehicle. Once everybody had stopped amidst a smell of hot tyres and brakes, I became very angry and could easily have got out and had a good set too with the idiot who caused it all. But I didn't. Instead I tried to ignore it and ended up shaking like a leaf later and being unable to sleep. But enough of that.

Yesterday there was some dx, including CT1XC on 4m. Being in Coimbra he was in a new square for me - IN50 (1793 km).



So I have managed most of my targets for 4m this year already. Must set tougher targets.

I also worked the usual 4m suspects, CT1FFU (IM59 1897) and CT1HZE (IM57 2122).

There was a good opening on 6 metres, but I spent most of that chasing round a fault on the antenna. I connected the 6m antenna to the Flex and everything went weird. After quickly checking that every plug was tightly screwed up, I started at the antenna end and worked towards the rig (a mistake, as it turned out).

When I moved the SWR meter the antenna lead fell out of the back of the compression PL-259 plug. Strange. It turned out that the centre had not been soldered. Anyway, after a lot of ferreting about, it also turned out that even when the coax was in the plug there was an open circuit between the barrel and the pin. As the antenna is an HB9CV there should be a DC short. Without the plug, the braid and centre of the plug had a short circuit, so how could the plug be faulty?

There then followed a long spell of trying to resolve this issue, and eventually I changed the plug for another compression one and still it would not work. Then I found a thin sliver of the coax dielectric was sitting proud of the washer and stopping it making contact with the barrel of the plug.  It was very thin and almost invisible to my eyes.

Quick snip with the knife. Problem solved.

Except it wasn't.

After checking with the antenna analyser that a good match at 50MHz was out there on the end of the co-ax, there was no signal on the SWR meter. Not into the dummy load either. Could the SWR meter have failed at the same instant. No, but change it anyway. No still nothing, can 2 meters fail at once? Can 2 faults happen at once?

Yes, two faults can happen at once. If you forget to solder up a compression PL-259, it can fail when you moved the meter, but the original fault lies somewhere else. Took me a while to work that out.

Attention then turned to the patch lead between the meter and the Flex. Sometimes I buy these rather than make them and often they fail after a while and need to be resoldered. It was OK.

Finally my attention turned to the way the patch lead was connected to the Flex.

The Flex has BNC sockets. At some stage I have been in a rush and turned to a BNC to SO-239 socket to make the connection. Better would have been to make a single patch lead with a BNC for the Flex end and a PL-259 for the SWR meter end, but that takes time. Why not use my reliable BNC to 239 patch? That is hardly likely to fail...
The idea is not as crazy as it seems, as it allowed me (from time to time) to swap out the SWR meter and occasional linear and connect the 6m antenna direct to the Flex, or switch to the HF antenna, etc., using the SO239 socket.

It looks like the brass inside the pin slot of the socket has lost its spring, become deformed or broken. Anyway, it has stopped gripping the pin, and hence the basic problem.

I had bought the lead ages ago from Garex to release the strain on a handheld used in the car (I use handhelds as mobile rigs). Somewhere along the way, the handhelds changed over to smaller connections, the BNC one was redundant, migrated to the shack, and ended up here. There was no plan to it, it just happened by chance, Your Honour.

The whole process of fixing this took a couple of hours and I was QRT while I struggled with it.

It often says on railway level crossings "one train can hide another", a warning against impatience. I should paste on my shack wall "one fault can hide another".

If the compression plug on the SWR meter had not allowed the coax to pull out at the precise moment I was looking for a different fault, and if the coax had not happened to allow a tiny piece of plastic to prevent it being re-installed, a lot of this frustration would not have happened.

However, the basic cause to both these things was impatience on my part. No doubt in a hurry to do something else, I did not remember to solder up the compression plug. And no doubt to avoid making a BNC lead I used the handy patch. In both cases I should have done a better job. The fact that both situations worked without a problem for years does not excuse me.

Guilty of slack working.

I promise to be a reformed character and not cut corners again.

Now, I am off to shut my eyes - but when I do I only see a red Ford Fiesta sliding towards me at great speed.

73

Jim
GM4FVM
P.S. I am just pasting the QSL image into the text. I do not know if this shortcut will work; if it doesn't I will do a proper job of saving it as a file and adding it later. But I am busy and I need to get on and do some work ... as the Simpsons say, "do it the American way ... do a half-assed job" (I can do those here too).
Edit - the shortcut didn't work so I have saved the file. So much for short cuts. Don't I ever learn ????

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