Tricks of the Trade
Last Modified: August 17, 2010
Contents: Basics; Antennas; Bonding Material; Coaxial Connections; Fasteners; Save Your Money; Tools; Wiring;
I took so much time learning the tricks of the trade, I never learned the trade!
I think the above speaks for a lot of us. However, over the years I've learned a few tricks, so this is one way to pass them on. I've broken them down into several categories, so you can use the links above to take you to your interested section.
I'd like to lay claim to all of these, but the truth is they're not all mine. If I know who I got the idea from, I mention them (or it), and who knows, one of them might be yours!
Frequent visitors will notice some of the tricks are listed in other articles, but I thought it prudent to lump them altogether as well.
The old adage about a chain being only as strong as its weakest link is true, and that speaks for antennas as well. I've been lucky, and I've never lost an antenna due to a component failure. However, I have a few friends who have. There are several scenarios which can cause an antenna failure, and one of those is the lowly 3/8x24 stud.
Some stainless steel ones are okay, as they have a tensile of about 60,000 psi. The black ones sold by most hardware stores have very low tensile strength (<20,000 psi), and they rust easily, so avoid them. If you have a heavy antenna, and you're worried about the bottom stud or bolt breaking, here's a suggestion. Most Ace hardware stores carry Grade 8 bolts in 3/8x24. The head of the bolt will have 6 hash marks, and they're usually plated with an anti-corrosive which give them a yellow/green hue. If you need a 3/8x24 stud, you can easily cut the heads off and polish them with a Dremel tool. With a tensile of 150,000 psi, they're not liable to fail.
I mention this in my Antennas, Commercial article, and it bears repeating here. The Hustler® HF mobile antenna coils are held on the mast by a pressed-in stud with about 5 complete threads. If you overly tighten the coils, the ferrule will eventually loosen inside the mast. The result is a lost coil, and possible damage to those vehicles behind you. The safest way to make sure you don't lose one, is to guy the coil. Just make sure the material you use is not RF conductive! Phillystrand®works well as long as it isn't wet.
Flat, braided copper strapping isn't as difficult to find as some folks think. In most cases the shield salvaged from discarded RG8 will do just fine. You can lightly score the outer cover with a utility knife which will allow you to remove it. Just be careful not to cut clear through to the shield. The older the coax is, the easier the job.
Sometimes, the shield turns dark due to migration and contamination from the plasticisers in the outer cover. It can be easily removed with DipIt® or other tarnish removing liquid. Just remember to rinse and dry it before you try to solder lugs onto it.
If you're after the braided heavy-duty, 1 inch wide material, you can buy that from AES, HRO, and most other amateur radio dealers. Or, you might look here: Electric Motion. Their EM2080 product has eyelets crimped along its length which facilitates installation.
Sanding off paint down to bare metal is not advisable, as this removes the underlying zinc coating which facilitates rusting. All you need to do is use a star washer between the strap and the body. If you can find them, use the I/O style with teeth on the inside and outside as shown above left. Remember, zinc is self healing, so once you tighten down the connection, the zinc will do its thing and seal the connection from the elements.
3M's 1181 copper foil tape isn't technically bonding material, but it's good for shielding all sorts of RFI sources. These include wiring harnesses and spark plug wires. The adhesive is conductive,and it solders very easily. Type 1182 has adhesive on both sides for special applications, and there is also an aluminum version (1170). All come is various widths with 3/4 and one inch the most common sizes. It isn't inexpensive, but you can often find it discounted on ebay and other on-line auction sites.
I have an article which explains how to properly install UHF (PL259) coax connectors. However, tricks of the trade should include good tricks, and tricks to stay away from. One to stay away from is the PL259 crimping tool. Supposedly, the crimper offers as good a connection as soldering does. It doesn't! The ARRL reviewed the tool, and came to the same conclusion I did without trying one first-hand; the brass barrel tends to crumble, and the coax can be easily rotated inside the barrel. I understand they're no longer on the market.
Perhaps part of the problem is learning the skill to properly install PL259s, with or without the adaptor sleeve for the smaller diameter RG58 and RG 59 (RG8X) cables. It is not only the skill which needs to be learned, but having the right soldering irons (not guns!). If you really want to learn how to do it, read the article.
I usually seal my outdoor PL259 connections with 5/8 inch ID, double-walled, polyolefin heatshrink tubing. It isn't inexpensive (about $9 per foot), so not too many people use it. If you have a need to seal coax connections, here's an alternative; Rescue Tape®. It is self vulcanizing, and will seal out the weather like no other product, bar none! It is almost magical. The best part is, it's easy to remove when necessary. You can buy it directly, of at most Ace Hardware stores.
One thing you don't want to use, although most amateurs do, and that's vinyl electrical tape. Contrary to popular belief, it allows moisture to seep in, and even the really good grades tend to harden over time. Plus, there is always a residue left when you remove it. This is also true of coax seal, dum-dum, and just about every other tape product, except Rescue Tape®.
There are about as many different kinds of fasteners in the world as there are people, or so it seems. All the rage these days are self drilling, sheet metal screws. They're great for thicker materials, but if you're using them on thin sheet metal, they don't work very well. The best solution is to use a very sharp punching tool and hammer, which will roll the edges of the sheet metal over as the punch is driven through as shown at the right. This gives a sheet metal screw (self drilling or otherwise) a larger surface to grip onto, and less likely to loosen.
You can buy all kinds of screws, bolts, fasteners, clips, etc. from your local Ace Hardware. However, if you're looking for something really off-beat, here's a good source; Fastener Super Store. They even accept PayPal if you're into such things. Incidentally, they carry the aforementioned I/O star washers.
Another good source is Aaron's. They carry a very wide assortment of both inch and metric sized bolts, nut, washers, and fasteners. Even the really weird security items which are seemingly impossible to find.
We all need to bow to the East or whatever, to thank Thomas & Betts for the Ty-Rap®. The problem is, not all plastic ties are made by T&B, and in most cases the off-brand ones are inferior. If you visit their web site, you'll learn why. Honest-to-john Ty-Raps® utilize a metal keeper rather than a plastic one which makes them ever so much stronger. You should select the all-weather ones which have ultraviolet stabilizers for long life.
If you don't mind paying the premium, you can buy T&B Ty-Raps® that have a metal core running along their length. So help me, you can almost tow a car with one of them! Their web site lists their distributors, including GrayBar Electric. By the way, Ty-Raps® are available with eyelets in the ends, so they can be screwed down. I've tried those plastic clips which use double-sided sticky tape, and have never had them stay on!
The title of this section is probably misnamed, and here is why. At a recent hamfest, I notice a nearly new Ford Econoline van. Mounted hither and yon were 5 radios, 4 of which were FM units. Each one of these had it's own wattmeter. What's with that? Not only do you have to find room to mount them all, they become a major distraction! When I ask why so many meters, I got an inane answer.
The real fact is, if you did your install correctly, you don't need a wattmeter/SWR bridge on an FM radio! If you just have to know it is putting out power, buy yourself a cheap field strength meter which will work for all of your radios, HF through SHF. Further, you don't need a wattmeter/SWR bridge on an HF radio either, unless you're manually controlling a remotely tuned antenna.
When I say save your money, I really don't mean it. What you need to think about is buying the needed tools, and forget about the superfluous ones.
Want to know one of the most frustrating things in amateur radio? Believe it or not, it's not having the right tool for the job. Just as bad is having an inferior tool!
Referring to the tools at left; the one on the top is a Radio Shack RJ45 crimping tool, and the one on the bottom is from Allen Telephone. The RS one cost about $15, and the good one was nearly $50. One of the reasons for the difference is the crimping die in the Allen tool can be changed. This allows the tool to crimp not only RJ45 cat and telephone cables, but special ones like those used on Icom microphone cables.
Probably the most used tool is the lowly wiring lug crimp tool. Here too, there is a great difference in quality and capability. The tool (top right) is made by Thomas & Betts, and one I've owned for 40+ years. The one on the bottom is a $6.95 special from a hardware store. Yes, the cheap tool works, but the connections aren't nearly as good as those made by the T&B tool.
Here are three more specialized tools. The top one is used to crimp D-style connector pins. With the die, it was nearly $50 some 20 years ago! One thing is for sure, it beats having to solder the pins and melting the connector at the same time.
The center tool is designed to crimp F connector sleeves. Although they aren't often used in amateur radio, the tool can be used to crimp large wiring lugs like those used on welding cables.
The bottom tool is from West Mountain Radio, and is for Anderson Power Pole connectors. It handles 15, 30, and 45 amp units, which are the most common ones used by amateurs. The larger PP120 and PP180 can be crimped with the aforementioned F connector tool.
While I'm on the subject here's another wiring trick. After-market sound system wire, and welding cable are what's referred to as high strand. All this means is, the wire itself is comprised of a large number of smaller strands which makes the wire very flexible. It also wicks solder as a result. Unless you own a solder dip pot, you shouldn't attempt to solder high strand cable. If you do, you run the risk of wicking the solder past the crimp. If the wire is subject to vibration, which it is in a vehicle, this is the first place the wire will fail. Therefore, it behooves you to have the correct crimping tool to do the job right!
One of my favorite suppliers for hand tools is TecraTools. There are places where you can buy less expensive tools, but if you want quality, this is the place to go. They're located in the Denver, Colorado area.
It's difficult to find decent fuse holders these days, especially for Maxi sized fuses. When you do find them, connecting large lugs (#6 and larger) can be difficult. The wire size on those with pigtails are always to small for the load, require butt connectors, and there is no convenient way to fasten them down.
The solution is Anderson Power Pole connectors, which are available from West Mountain Radio (and others). The PP15-45 will hold an ATO fuse (40 amp max), and the PP75 will hold a Maxi fuse (80 amp max). The connectors are keyed allowing them to be sandwiched together. The keyway groove (used to lock the connectors together with a small roll pin) can be used to screw them down to a surface.
If you use PP connectors as fuse holders, you have to make sure the connector lugs themselves are fully seated into their respective housing. The blades of the fuse needs to be positioned between the lugs and the tension springs built into the housings. If the fuse simply falls out, you haven't done it correctly! Further, the blade thickness of the Maxi fuses makes insertion rather difficult, albeit not impossible. Personally, I prefer to use fuse holders made specifically for the Maxi fuse. Unfortunately, the MAB1 Littelfuse Maxi fuse holder is a discontinued item. However, Newark (at last check) had several hundred in stock.
I do have one suggestion. Anderson Power Pole connectors are very convenient, and make very secure connections. Once you start using them, you'll enjoy their ease of installation. That is, if you bite the bullet for the crimping tool. While it's about $50, it sure shortens installation time. Probably the toughest lesson to learn when you're using zip-type power cords, is orientating the connector pins on the ends of the wire correctly. If you'll read the directions that came with the crimper, you'll do it right the first time. But... if you're into using the PP75, PP120, and PP180 connectors, you'll need Anderson's commercial-grade crimper. Yes, it is expensive (>$200), and hard to justify, so there are others ways (see below).
The PP120 and PP180 size connectors are great for high current uses (mobile amplifiers for example), and will hold up to #2 cable. However, the aforementioned $50 tool will not crimp these high-amp connectors. However, an F connector sleeve crimping tool works well. I always solder these large-sized connectors (not a necessary step if crimped correctly). If you decide to solder them, just remember my comments about high strand wire above.