Archive for category Amateur Radio
The main reason for taking the FC1002 frequency counter apart was to replace the failed quad-AA NiCd battery pack. Rather than buy new cells with tabs, I recycled some low-discharge “ready to use” NiMH cells from the heap. Back in 2009, they looked like this:
Nowadays, they’re a bit less peppy:
The red blooper shows that you can’t trust a smart fast charger to get the right answer; it concluded that pair was fully charged. After the discharge test and an overnight C/10 charge, they regained as much enthusiasm as they’ll ever have.
They have slightly less capacity than in 2009 and also a somewhat lower terminal voltage. That shouldn’t matter here, as the frequency meter has a power supply to take care of that problem.
Although I’ve sometimes been able to (quickly!) solder directly to ordinary AA cells, a trial run on a defunct RTU cell showed that wasn’t going to work on whatever variety of steel they used, no matter how much I scuffed it and despite using aggressive flux that normally blends silver solder onto stainless steel.
Fortunately, the top half of a four cell case fit exactly in the space available, so I used woven copper fabric tape inside the case to interconnect the cells, then lashed everything together with the obligatory Kapton tape:
That cracked faceplate isn’t the nicest thing to confront, but it’ll suffice until I get more motivation:
I’ve misplaced my stack of Round Tuits again…
The plastic faceplate over the display cracked quite a while ago:
I don’t recall dropping the poor thing. Given the interesting pattern, it could be inherent stress that finally let loose as the plastic aged.
While I have it apart to rebuild the battery pack (more on that later), I’ve been easing acetone/MEK into those cracks by capillary attraction in the hopes of dissolving just enough plastic to rejoin them, without slobbering solvent all over the faceplate and scarring it.
If all else fails, I suppose I can mill out a replacement from thin acrylic sheet, but those nicely rounded cast / molded edges lie well beyond my abilities…
It arrived with a plastic grid embossed with the helpful notation “Use this height adapter under battery if necessary”, but I figured lower was better. A little bending, two snippets of mouse pad (remember mouse pads?), and a section of white plastic rod faced off / drilled on the lathe anchored it flat on the platform with no wiggle room at all.
With any luck, that’s the last battery the van will ever need…
One of the battery packs powering the GPS+audio interface on our bikes has completely failed, with zero volts at the output and no charge indication. The other five chug along as well as can be expected:
The push-to-test button on Pack 4 has become increasingly erratic over the last few months, rendering the charge status LEDs mostly useless, so it has two curves: the lower capacity came directly from the bike, the higher hot off the charger.
For reference, here’s what they looked like in May 2012:
And right after they arrived:
Given their nearly constant use and charge cycling, I’m impressed.
Those Lenmar DVDU923 packs look similar, at twice the no-name 2010 price. So it goes…
The DCRT folks held a “soft opening” last week at the bridge over Rt 55 completing the rail trail from Hopewell Junction to the Walkway Over the Hudson; the Hudson Valley Rail Trail continues westward to Lloyd. I hadn’t actually planned to ride the whole thing, but Monday was a lovely day and, hey, why not?
So here’s what a pleasant, mostly off-road 36 mile ride looks like:
Hadn’t realized it was Columbus Day until well into the ride, which accounted for a Hudson River crossing at 3 mph embedded in a solid 1.5 mile scrum. Being no fool, I returned over the Poughkeepsie (a.k.a. Mid Hudson) Bridge.
Back in the day, you wrapped with cork tape and had to worry about the direction on each side. Silicone tape fuses into a solid mass and the orientation shouldn’t matter; that’s a Good Thing, because I’m not sure what direction would be correct in this situation.
The yellow section covers the SRAM twist grip, which means it has a moving joint at each end. I suspect the tape will pull back from the larger part of the grip and form an unsightly lump just behind it.
It’s certainly much grippier than I expected…
The first two charges for those Baofeng BL-5 batteries show that the actual capacity isn’t quite up to the 1800 mA·h spec:
The (meager) instructions say that the batteries will reach “full capacity” after three charges. Unless there’s a miracle waiting in the wings for that third charge, I very much doubt that they’ll get any better than the 1400 to 1500 mA·h you see in that graph. Note that the two batteries have quite different capacities and that the capacity for Pack B decreased on the second charge (purple vs. green trace).
Compare that with the Wouxun batteries (plotted with Gnuplot, rather than a screen grab):
Those are all at 250 mA, which is certainly less than the peak current and probably more than the average current. It’s close enough for now, anyway, and shows that the Wouxun batteries actually live up to their spec.
Huh. Who’d’a thunk it?
It looks like the blinky lights should go into power-save mode under 7 V, because there just isn’t that much capacity left when the cells start rolling over the edge of the cliff.