nis ([info]nis_) wrote,
@ 2007-03-29 08:14:00
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Bicycle

I'VE PUT TOGETHER a complete solution to the bicycle mobile radio problem. I have an antenna; it does not require a ground plane to work (Larsen self-mount). I have a huge sealed lead-acid battery (25 lb. and has a 33AH capacity). I have the 2 meter FM rig (IC-2200H) and an SWR meter and a chunk of coax to join the SWR meter to the rig.

Okay so it's not a complete solution -- I haven't quite figured out the mounting of all this on the Lightfoot. But it's a good start and will also serve me well as a battery-operated radio solution during thunderstorms (indoors of course). I generally run around the house unplugging things as fast as I can if I hear one clap of thunder; and do so at a more relaxed pace if I note in advance one [storm] is on the horizon (generally checking the weather frequently enough to be ahead of this).

My mother used to tell me about her grandmother; how she went out into the field to light the holy candle (whatever that was wasn't specified further) either during or just before a storm. My mother also did not like to see anything plugged in during a storm, and I think she even knew enough to keep the end of the cord away from the outlet it was just unplugged from.

I have tens of yards of cables here and I roll them all up -- and I do mean all of them -- for every storm. It's quite a sight afterward but it does keep me somewhat aware of the little short-cuts I take in cabling things together here.

 

FINALLY GOT a decent high-visibility jacket, and oh what a jacket it is. This thing is magic -- I was out shoveling during our March 2007 Nor'Easter (on St. Patrick's Day) -- a quarter after midnight. Sleet ('dry' sleet) was hitting me in sheets -- it was like being at sea, at times. The winds were gusting, and all the new fallen snow was systematically turning into a heavier mix on the ground. I was shoveling for all I was worth, but still fairly relaxed and taking my time.

Here's what I had on: a Tilley hat (T3); two cotton t-shirts, a heavier long-johns type of shirt (thermal waffle-stamped cotton inside and flannel outside in two layers; fairly thin); my farmer's jeans (Carhartt), an Oxford shirt (just to protect the outer shell from any tears the buckles on the farmer's jeans might offer)… and the new high-visibility shell, which is nearly as thin as silk. I could not fit even one sweater under the new jacket, which is why I layered with four shirts, all which fit easily under the jacket (but were a bit restrictive of motion).

It was 22°F. Sure it was a bit brisk for five minutes, but as I'm out of shape, whenever I do exert myself I quickly heat up -- my core temperature goes up. I was astonished though, that my ears were not just warm -- they were hot. I mean hot. I degloved a hand to verify this -- hot.

No ear protection.

The Tilley was doing its job, keeping the precipitation off my neck and ears (no scarf either). I always wear a scarf. I haven't figured out what's going on, quite, but the shell was just outstanding in performing under these conditions. I was certain, prior to obtaining it, that I'd need a much heavier set of clothing to go venturing out in 22°F weather, and I was concerned because I've made up my mind to become much more visible on the bikes, which means high-visibility colors worn on jackets. As I have none (besides the new shell) I was pretty sure I'd need a second jacket for colder weather.

Doesn't appear necessary since acquisition of the new shell.

Also, it folds to nothing -- much more thin and supple than any sort of modern fabric I'm used to working with -- I generally wear 'pack cloth' type of jackets, generally from a good outdoor supplier specializing in technical sports such as mountaineering and rock climbing.

I haven't heard from Lightfoot, and the trike is due to ship around 5-7 weeks from now or thereabouts. It is so hard not to write, not to wonder if my order got lost -- but I have confidence in them. I have a good eye for quality online vendors, and when I step outside my comfort zone, I'm almost always aware I am doing so -- never got that feeling when dealing with Lightfoot; they're a quality shop.

It's been a winter (can't bring myself to call it a long one; statistically that's untrue). Long for me, regardless -- I want some time on the road on wonderfully sunny mornings before traffic stirs.

 

HAULING AROUND a 25 lb battery on a trike might sound harsh or laborious, but I'm thinking differently. As the trike is compound–geared (two separate drive trains joined by a jack-shaft) it has plenty of easy gear-inches available for the most monstrous hill-climbs. I don't expect to tote the battery on every trip, but on the longer ones I'd like to have a 2 meter rig on board, and in these hills I don't think an HT is going to cut it. At any rate I've got it covered for maximum bicycle-mobile operations with 33AH to draw from.

[put in a blurb about what 33AH achieves.]

There's another device that's important to this -- if you read the owner's manual of any modern (automotive) mobile radio, it'll say quite clearly in the specifications that the radio is designed for 13.8 Volts, DC. Why they design it around that number I'm not sure about -- it may be the center-voltage of a typical car battery (or the combined effects of a car battery and the rest of the charging system in a car).

But for a battery that has to stand on its own -- no alternator replenishing it -- batteries sag. They quickly lose their terminal voltage, and can drop below 11.7 volts fairly early in the discharge curve.

Enter the battery voltage booster.

The booster takes a lower voltage (perhaps 10 volts) and boosts it higher, to a useable value. The one I'm acquiring will boost from 9 Volts to 13.8 Volts -- and hold it there, until the battery that is feeding it is exhausted (or sooner, if you manage it well). In fact 9 Volts is probably way too low to be draining a 12V battery -- might be catastrophic (killing the cells). However, there is a large useful charge left in a battery as it is transitioning just below the specified 13.8V +/- 15% (that's 11.7V on the low side) typical of mobile 2-way radios. It is that segment of the discharge curve that interests me, and that this gadget is designed to address.

All this thing does (in simplest form) is it creates an electrical oscillation such that it is able to drive some kind of transformer (it creates AC from DC so that a transformer can be utilized; transformers do not generally work with DC, as they require fluctuations in current to induce a voltage in the secondary winding). Once a transformer is employed, it is no problem to vary the ratio of the two transformer windings (coils of wire) which changes the induced voltage from whatever it is to whatever is desired. In this case, a step up from (perhaps) 10V to 13.8V (though it is certainly some other value while it is rendered in AC, it must eventually be converted back to DC to drive the mobile radio).

I knew that running a mobile radio off a lone lead-acid 'car' battery was not going to work out well, unassisted -- these radios are designed for a working automobile, not a lone battery. It was bothering me and I didn't want to address it; I knew it was going to cost some money to do so but I also knew the problem wasn't going away. The difference is I was determined to make the overall scheme succeed, so I kept tugging at the thread, doing more research. Eventually I supposed there must be a device in between the battery and the radio to do what I've described above.

It turns out that there is such a device, and that a very few companies vend them at hobbyist-grade prices. I'm not sure, quite frankly, what kind of a price I got, but I found someone making these things who was showing they understood the issue thoroughly. At least that's my impression; I'll know in a week's time if I got that one right. Again, though, I have a nose for this kind of thing, and I'm confident in the package I've put together to solve this engineering problem.

 

I'VE PUT UP another of Grumpy's stories -- jeez, I gave the guy one stolen suggestion (from Hemingway) to 'write only what you know about' -- he said he followed my suggestion, and I agree, he did.

You can view the results for yourself at grumpy1942.livejournal.com.

My in-basket is getting full -- Grumpy keeps giving me manuscripts to type into his journal (he has no Internet access and asked me to 'cut the word "computer" out of the dictionary').

Doesn't want to know about it, and overall I'd agree.

 




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