HAM TO HAM - #3

Two months months have passed now since we inaugurated this column within the pages of 73 Amateur Radio Today magazine. Input from you, the reader, has begun to materialize, but we still need a much more enthusiastic response in order to fill this space with the very best of information that's available. We're looking for tips, ideas, suggestions and techniques that will help our other readers in their pursuit of amateur radio. Whatever you feel might be helpful, things that you've discovered in your own ham career that have proven worthwhile, both technical and from an operational standpoint. Everyone has something to contribute, the key to unlocking the idea for the rest of us to share is to sit down and write to me about it. Make your point as clearly as you possibly can, including all details, schematics, sketches, etc. Whatever you feel would be helpful to get your point across to others. One of the secrets to making sure that your written suggestion clear, is to have a friend read it over first, preferably one who's not familiar with the idea. If he has any questions, then you'll know what else you'll need to include for best clarity. We're looking for workable, proven ideas and suggestions, ones that will be repeatable by others with the same or similar problem and ones that haven't been published elsewhere. Send your contributions to:

73 Magazine's Ham To Ham column
c/o Dave Miller, NZ9E
7462 Lawler Avenue
Niles, IL 60714-3108

For each idea used within this column, Uncle Wayne will send you ten real U.S. dollars for your time, trouble and postage costs, but the real satisfaction is in knowing that you'll have helped others benefit from your experiences and knowledge.

If you've sent in ideas and suggestions to other publications, only to be ignored or forced to wait for months - years? - to even receive a response, I can guarantee you that it won't happen this time. I'll acknowledge all legitimate contributions expeditiously, giving the contributor an idea of whether his or her idea will be used, and roughly when. Nothing turns people off more quickly than to have their ideas and suggestions viewed with indifference...I know...I too have been ignored at times by other publications. I promise you that it won't happen here, it's one of the reasons that I first contacted Uncle Wayne about starting this type of column in the pages of

73. We need a place where good ideas are valued enough to be treated respectfully, and this is it.

There are tons of good ideas out there. With all of the equipment now available to the average ham and all of the different and varied modes of operation, any number of problems and their solutions have to have been discovered by Joe or Jane average ham. These are the ones I want to hear from. The dyed-in-the-wool engineers and contemplative theoretical physicists are welcome to send their thoughts, ideas and drawn-out treatises to the other magazines. We're looking for real hams with solutions to real ham-related problems, within the down-to-earth context of our hobby. As the masthead says, Ham To Ham, not physicist to physicist or theoretician to theoretician.

By the way, I've no problem with engineers, physicists or theoreticians particularly, it's just that I don't think that most other hams are really all that interested in long, boring soliloquies on concepts that can be explained much more succinctly. Brevity in explanation is often the key to understanding; it's surely the key to staying awake after a long day at the salt mines while you sit back and read the latest issue of 73. Not everyone who reads a magazine like this one, or who holds an amateur radio license for that matter, is an engineer, nor may they be involved whatsoever in the electronics profession on a day-to-day basis. I've the feeling that most of the folks who might be reading this just want a straight-forward solution to a perplexing problem within the hobby, and that's where this column is heading. If this is vastly different from your own interests in the pursuit, try to step back and view it from that perspective. Now, if what I've said is already your viewpoint, or you can at least momentarily make it your viewpoint, then sit down and write about some of the things you've run into with commercially made equipment, antennas, station accessories, etc. and send them in to me. Knowledge is only usable if it's in understandable form. 73 Magazine has always had the reputation of being a practical showcase for real hams, with real, duplicatable ideas and articles. Let the others print things that no one wants to read, build or do, we'll stick to actual reality, not virtual reality.

When you do contribute ideas to this column, however, please try to be fair to the manufacturer of the item if you have a suggestion for an improvement Everything ever made can be improved upon. Equipment manufacturers often sacrifice one feature for another, or they may drop something because of cost and competitive design reasons. We're usually wrong if we consider everyone other than ourselves to be fools! We're also definitely not looking for unsubstantiated complaints nor libelous accusations about any particular manufacturer or company. That's not the purpose of this column. Our purpose is simply to help others who might be experiencing the same or similar problem with a piece of gear, with the thought in mind of fixing the problem, not fixing the blame for it.

Anything in and around the ham shack is open for acceptance on this page. We're all involved in electronics in general, as well as in amateur radio specifically, so consider sending in ideas that may not seem solely for use in ham radio - though I do want to keep the main focus along the ham equipment lines. In fact, my first tip this month is something that reaches beyond the ham shack and into the world of TV's, VCR's, etc. as well.

A Simple Infrared Control Verifier

Some of the current ham gear is showing up with infrared remote control capabilities, just like the vast majority of new TV sets, home VCR's, stereo audio setups, etc. Infrared headsets and microphones have also invaded the ham shack in the interest of keeping desktop cable clutter to a minimum.

Here's a simple way that you can verify if your hand-held infrared remote transmitter is at least putting out a signal when a button is depressed, since our eyes can't see an IR beam of light directly. By the way, many of the problems with infrared remote controls can be traced to a faulty hand-held transmitter unit. Either a button(s) not making good contact, dead batteries or batteries making poor contact or a cracked PC board from one too many drops on the floor! But to test it, all that you really need to do is to tack an IR detector diode across the input of any high-gain audio amplifier, turn up the amplifier's volume, aim the remote transmitter at the diode's face, and you'll be able to hear the pulses being sent out by the IR transmitter. That's it.

Any high-gain audio amplifier that's usable down to microphone levels should work - such as the Radio Shack #277-1008 portable battery operated test amplifier. The IR detector diode can be one-half of an infrared emitter/detector set, such as the IR detector diode in the Radio Shack #276-142 combo. Even a glass encased 1N914 or 1N4148 silicon switching diode can be pressed into service, but it's much less sensitive than a real IR diode - did you know that all glass-encased diodes are somewhat light sensitive? They're temperature sensitive too, but the ones specifically made for light or temperature sensing are specifically formulated to enhance those particular properties.

Painting Antennas

I can remember overhearing a conversation on the ham bands one day - between two fellow hams who seemed to know each other fairly well - on the virtues and drawbacks of painting a new 2-meter vertical antenna that one of them was planning on putting up soon. The one putting up the new vertical asked the other if he thought that painting his new antenna, to help preseve it, would be okay. The second ham answered very authoritatively "Oh my gosh, no, you'll be insulating it from the air and it won't work!"

Even though we talk about getting on-the-air, and our signals radiating through the air, direct contact with the air isn't a factor in whether a particular antenna works well or not. When the astronauts were on the moon's surface, with no air anywhere except within their spacesuits, their radio signals made it back to earth in fine shape. The rubber ducky type of antennas seen on vitually every hand-held transceiver, though not in direct contact with the air, seem to do a pretty good job for the most part. In fact, I've painted several ham antennas using a flat lacquer-based spray paint without any regrets, only longer life from the antennas!

It's true that using insulated wire for a horizontal dipole will change the dipole's length requirements slightly, but it certainly won't prevent it form working just as well as a bare-wire antenna. Most people don't use insulated wire for wire dipoles simply because there's no point in paying for insulation that isn't really needed. A dipole is normally srung up high enough in the air to be out of reach of children and others, so insulating it from accidental human or animal contact isn't usually a factor. If it's not up high enough to be out of reach, I'd definitely opt for the safety factor of insulated wire!

But a thin coating of non-metalic paint on your 2-meter beam or vertical won't affect the resonant frequency to any appreciable degree and it certainly won't render it an ineffective radiator or receptor of RF energy. Just make sure that any metal to metal contact points aren't inadvertently insulated, and I'd stop short of getting any paint on the matching section - just in case it requires a minor change in tune-up - or on any insulating connection blocks to avoid possibly changing their insulating properties.

Before any painting, I would also make sure that the aluminum is thoroughly cleaned of any oil that might have been used during the machining process and that any shiny aluminum be lightly sanded to give better grip to the paint coating. Flat gray primer spray paint is usually a good choice for this type of situation since it's formulated for good adhesion on bare metal. And it's best to do all spray painting out-of-doors, in calm weather, for safety and health reasons.

A Word Of Caution In Using Spray Contact Cleaners Near RF Circuitry

Spray contact cleaners, those commonly sold to clean noisy switches and potentiometers, should be used with a great deal of caution around any parts carrying RF voltages and high RF voltages in particular. This would include using these sprays on any band-change rotary switches used in many of the older ham transceivers, linear amplifiers and the current lineup of manual antenna tuners.

Before the broad-band, no-tune final RF stages became commonplace in ham transceivers, most rigs used mechanical, multi-section rotary switches to accomplish all band-changing functions within the radio. The temptation to use ordinary spray contact cleaners on these switches, however, especially the sections carrying high voltage RF, should be strictly avoided.

Many of the popular spray cleaners will leave behind an oily deposit, used to lubricate the item being cleaned, but in RF circuits, this oily deposit can soak into the switch's insulating wafers, causing them to lose some of their non-conductive RF insulating properties. That oily surface will also cause dust and grime to collect on the insulator, futher exacerbating the problem by gradually creating a semi-conductive surface on the insulating wafer. The final result can be arcing and eventual carbonization of the wafer material - particularly if it's of a phenolic base - with almost certain destruction of the switch - and perhaps other associated parts - in the end analysis.

The lesson to be learned here is to never use ordinary control-cleaning spray on RF circuit parts, particularly if that spray leaves behind an oily lubricating film. If RF switching sections absolutely must be cleaned, take the time to do it by hand, with a swab, using only small amounts of cleaning medium and then only a medium that will evaporate completely without leaving behind any left-over residue. In reality, rarely do these switches need any more cleaning other than simply being "exercised" several times through their entire rotational range. The switch contact wipers will usually clean themselves with this simple procedure. They're normally plated with silver, and even though the silver appears black because of tarnish, silver oxide is nearly as good of a conductor as shiny silver, so don't be fooled into thinking that a "really good" cleaning is needed. Looks can sometimes be deceiving.

I'll return with more Ham To Ham tips, suggestions and techniques next month, but in the meantime, jot down some of your ham-related favorites and send them to me at the address shown near the beginning. I'm not able to return all submissions, however, so please make sure that you send non-essential copies, or include a self-addressed and stamped envelope for any material that you must have returned to you and I'll do my best to get it back - no guarantees though. But here's the best part, Uncle Wayne Green will send you ten dollars for every tip that we use in this column, plus make you a hero with all of your fellow hams! What an incredible deal!

73, DE Dave, NZ9E

Note: The ideas and suggestions contributed to this column by its readers have not necessarily

been tested by the column's moderator nor by the staff of 73 Magazine, and thus no guarantee of

operational success is implied. Always use your own best judgment before modifying any

electronic item from the original equipment manufacturer's specifications. No responsibility is

implied by the moderator or 73 Magazine for any equipment damage or malfunction

resulting from information supplied in this column.

Please send all correspondence relating to this column to 73 Magazine's Ham To Ham column,

c/o Dave Miller, NZ9E, 7462 Lawler Avenue, Niles, IL 60714-3108, USA. All contributions used in

this column will be reimbursed by a contributor's fee of $10, which includes its exclusive use by 73

Magazine. We will attempt to respond to all legitimate contributor's ideas in a timely manner, but

be sure to send all specific questions on any particular tip to the originator of the idea, not to this

column's moderator nor to 73 Magazine.