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Odds and Ends


Some assorted side projects that have been interesting and/or useful.
A small parts dryer.
Parts Dryer Parts Dryer
This is really pretty obvious, but I thought I'd toss it out as having been very useful from time to time. Hair dryers seem to accumulate faster than I can find places to put 'em to work. As soon as they start burping out a little asbestos, the wife gets all funny about using 'em, tho' they seem to work perfectly well for my purposes.
I built this when I was learning clock-repair. Have since used it many times when I was in a hurry to get some part dry, either to continue with the project, or beat some agressive rusting.
Image: 400x277k, 26k
Ref: 299-5

A homebuilt base antenna a'la Jim Weir
From: Jim Weir
Newsgroups: rec.aviation.homebuilt
Subject: Re: base antenna for my handheld navcom
Date: Mon, 27 Nov 2000 08:20:55 -0800

"Ken Mattsson"
shared these priceless pearls of wisdom:

->My problem is that my home is on low grounds and on top of
->that we have a power line running along one side of our home
->yard. I can hear the traffic from our local airport traffic
->cicruit but not the ATC tower, so I would like to build or buy
->a "base antenna" for that. One that I could mount on a 30ft
->high mast AGL and hopefully be able to hear the tower as well.

Just to "try it to see if it works" here is the cheapest, dirtiest way to go. If you mount this on a mast and it works well, then we can figure out some ways to make it better and more weatherproof...

Get yourself a BNC female connector (UG-1094) and four ground lugs that will fit onto the threads of the connector (Radio Shack stuff). Remove the nut and lockwasher from the connector.

Get yourself two 22" (56cm) lengths of plain old "romex" #14 (1.6mm) house wire, or five 22" lengths of any #14 solid copper wire. If you use the romex, strip five of the internal wires so that you have 5 lengths of solid copper wire each 22" long.

Solder one end of each of four of the wires to a ground lug. You will wind up with four lugs, each of which has a 22" wire attached to it.

Solder the last wire to the center pin of the BNC connector.

(See last paragraph before beginning this step). Put the solder lugs over the center wire and onto the threads of the connector. Arrange them so that they are all at right angles to one another. Fasten them down with the lockwasher and nut that came with the connector.

The wire on the center pin of the connector is the "radiating rod". With the radiating rod pointing up, droop each of the four "ground plane" wires down at a 45 angle from the horizontal.

Connect a BNC cable between your radio and this connector, and away you go. In $US, this antenna costs about $1 to make without scrounging too much stuff.

The problem with this antenna, of course, is that the elements are rather flimsy. If you try it and it does your job, you may wish to replace the soft copper wires with heavier wire, brass tubing, or some other more rigid conductor.

(Before you tighten down the nut, you may wish to fabricate some sort of bracket to hold the antenna to your mast. It really shouldn't make a lot of difference whether or not the bracket is made of metal or a nonconductor. The easiest way is to get a piece of 0.050" (1.25mm) aluminum about an inch (2.5cm) wide and a foot (30cm) long. Drill a 3/8" (9.5mm) hole at one end of the strap, bend the other end into a 90 "L" shape, and use the center nut and lockwasher to hold this strap along with the ground lugs to the BNC connector threads.)

Jim
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com jim@rst-engr.com

Hole Layout Hole Layout in Brass Sheet
Rather than use lugs, I fashioned the attach for the ground plane wire into the mounting bracket, made from a piece of brass sheet.
Image: 400x266, 18k
Ref: 295-11
Ground Plane Attached Wires Soldered to Bracket
I used a propane torch to solder the wires into the bracket.
Image: 400x266, 18k
Ref: 299-17
Tip Connection Tip Connection
A bit of sleeve from a crimp-connector was used to join the BNC and wire.
Image: 400x266, 25k
Ref: 299-15
Assembly Complete Assembly Complete
Here the BNC is mounted in the bracket, with the 'radiating wire' heading out the opposite direction from the ground plane wires.
Image: 400x290, 23k
Ref: 299-13
Installed in Rafters Installed in Rafters
The ground plane wires are splayed out at 45-deg, and the bracket is screwed to one of the rafter diagonals.
Reception is usefully better than the rubber-duck that came with the handheld radio. Cost -- about $12, mostly for the 12' BNC-terminated wire.

("Can it pick up Duluth?"; "Ah, my boy, it'll pick up Tierra del Fuego!" - Firesign Theatre)
Image: 400x290, 21k
Ref: 299-10

Send questions, suggestions, or other remarks to me (benton@siletzbay.com).

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