SCANHINT.TXT October 1990 Written by Nigel Ballard 28 Maxwell Road Winton Bournemouth Dorset BH9 1DL ENGLAND Hello again, This article will just be a mishmash of my scanning hints and tips, these were gained from both personal discovery, and nicked out of other peoples various scanning publications. I guarantee you this will be one disjointed article, mainly as it will be written over a period of days, and will cover many different subjects. If you are willing to accept my lousy grammar, then please read on. GOING COVERT! I understand that in certain US states, going mobile with a scanner is against the law, something to do with thwarting the policeman hidden behind a bush armed with a menacing looking hair drier (RADAR GUN). In the UK however, going mobile with a scanner is not illegal, it is what you are tuned to that is guaranteed to get you in the Guacamole! Therefore, possibly the best way to avert the unwanted attention of the authorities, is to scan covertly. MOUNT IT! Firstly, mount the scanner in the glove box, and have the DC supply controlled via a switch mounted on the dashboard. Therefore if you get pulled by old smokie, you only have to hit the switch and all goes quiet. I guess leaning over to the glove box might indicate you are going to hide something, or worse that you are going for a gun! Taking it one stage further, use an external speaker, something with a good wattage rating, mount this low and possibly in the foot well aimed not at the floorplate, but at your ears. If you want to get really professional, you could put a volume pot in line, and also mount that into the dash. But there's still something that might give you away! THE ANTENNA Up until about one year ago, the only purpose built scanner antenna you could buy in the UK was the rather poorly engineered Radio Shack one. It was tuned for US bands as well which did not help it's performance over here. Anyway RS being RS, they sold very well. But to the trained eye they were a dead giveaway. Much like a discone on the roof of a house, it doesn't take a genius to work out what's on the other end of the coax. Likewise, with a mobile set-up, you may not wish the local police or car thieves to know you have something worth either checking out or worse stealing. *NOTE* As I type, because of the IRAQ/GULF crisis, I have a large amount of exotic RAF/USAF hardware flying low and fast overhead. I understand they are buzzing naval frigates off Portland Naval base which is near here. It's all to do with preparing the ships defences for the real thing. Anyway, as per usual I digress. MAKE YOUR OWN...Yep it's compromise time! Well of course you could buy one, Antenna specialists produce a whole range that are exact factory replacements for many popular US cars, or as we refer to them 'GAS GUZZLERS'. Trouble is, they are pre-tuned to specific bands, which is fine if you just want to scan 138 to 174MHz for example. But maybe your wallet will not stretch to such an item. Therefore in the time honoured tradition of electronics, we'll build the bugger ourselves. EASY VERSION buy a fairly robust replacement antenna from your local car mart. Using a sharp modelling knife, cut away the moulded joint where the coax meets the base of the telescopic whip. When you have bared just enough to see where the cable is soldered, un-solder the original cable and discard it. Get about four metres (do you use metres in the USA?) of good 50 OHM low loss communications cable with at least 80% outer braid. And using a good and hot soldering iron, make a new join to the whip. Make sure you get the joint good and hot as the metal whip will dissipate a considerable amount of heat, thus cooling your joint very quickly. When you have a good and shiny joint, get some ARALDITE or similar industrial glue, and remake the joint. It has to be totally waterproof as the elements will do their best to degrade the antenna's performance. Install your new whip, put a BNC plug on the other end, route the cable out of harms way (BRAKE PEDAL), and attach to your preferred scanner. If you intend to concentrate on 30MHz then fully extend the elements. If however you intend to scan UHF, try only extending just one element. It is important that the antenna is mounted on good quality bodywork. If you drive an old rust bucket then performance will be degraded as the antenna needs a good grounding with your cars bodywork. This will not be the best scanner antenna you ever used, but it is covert and cheap, and certainly kills a few hours on a wet and windy Sunday afternoon. HARDER VERSION The easy version is all well and good, but what about K-ROCK-FM, life just isn't worth living without a Phil Collins track every ten minutes! Accepting that you still want to use your car radio, then consider the slightly harder approach. What's needed here is a simple diplexer. I say simple because no R.F. is involved, therefore the task is very simple. This is what you need: 1/ 47 nanofarad capacitor (smaller the better) 2/ 200 OHM resistor (5% quarter watt) 3/ Small plastic box (one inch by one inch approx) 4/ Chassis mounting motorola socket 5/ Two foot of car radio coax (I cannot remember exactly the OHM value) 6/ Two metres of good quality (80% braid) 50 OHM coax 7/ One BNC connector, or whatever your scanner uses. 8/ One Motorola plug 9/ Three cable ties 10/ Some insulating tape 11/ Good industrial strength glue (not superglue) HERE GOES Mount the Motorola chassis socket into the plastic box, drill two small holes in the other end of the box, just big enough to run your two pieces of coax through. Solder one end of the capacitor and the resistor to the centre connector of the Motorola chassis socket. Bare about one inch off of each of your coax leads. Insert the leads through their respective holes. Solder the 50 OHM coax (SCANNER) to the free end of the capacitor. And solder the the car radio coax to the free end of the resistor. Join the two outer coax sheaths together and solder them both to the outer terminal of the chassis Motorola socket. secure the two coax leads with the two cable ties, this is to stop them being pulled out of the box. Use a little Araldite or similar glue to secure the coax and the two components. Make sure there is no way that the inner conductors, or the components can connect with the outer conductor. Put the lid back on your little box. Solder the Motorola plug onto the car radio fly lead. Solder your BNC onto the scanner fly lead. Now, gently remove your car radio from it's dash mounting, pull out the car radio's antenna lead, push it into your diplexer, take the car radio fly lead from your diplexer and push that into the car radio antenna socket. Push the diplexer back into the dash, out of harm's way. Run the scanner fly lead to the glove box or wherever you want it. Secure the diplexer with either a cable tie or some insulating tape. Re-install your car radio back into it's dash mounting. And there you have it. You will now be able to scan and listen to your car radio using your cars original antenna. This is not a World beating solution, but for a covert and VERY cheap compromise, what can you expect? POWER IT UP! Always better to connect your radio equipment directly to your car's battery. This will reduce interference from the ignition system. Also if like me you have a SAAB TURBO, and the poxy cigar lighter only operates when the ignition is turned on, then you will soon encounter as I did, that after getting carried away at a recent air show, when you decide to leave, the damn battery is as flat as a pancake. CHOKE IT If you still encounter interference from your car, whatever antenna set-up you use, then remember that some scanners (AOR2001) are pretty much immune to car interference, whereas some are not. Try adding chokes to the coil,distributor,windscreen motor. Or putting an in-line filter on your scanner power lead. And always, always put an in-line fuse on the hot side of your power lead. Many professional radio's in the UK now come with a fuse on the negative line as well. Use the correct size fuse, as too small and it will keep blowing. Too large and the radio will be well stuffed before the fuse decides to give up the ghost. And finally, always keep a few spare fuses in the trunk. WHAT ANTENNA SOCKET HAS YOUR SCANNER GOT. If you fancy yourself as a bit of a dab hand at soldering, then you might like to throw away those cruddy Motorola sockets and replace them with nice BNC ones. Now although the BNC is a far more superior socket with much less loss at 460MHz than a Motorola. There are however different qualities to be found. Firstly, you want 50OHM, 75OHM will not do. Why settle for chrome, when for a few cents more you could have a silver plated socket. If you are not over confident with soldering, get someone who is. Remember your guarantee may have just flown out of the window. *NOTE #2* Somebody who fancied himself as a bit of a coax expert once told me that if you have a 100 foot run of cable going vertically up a building, the cable loss was greatly less than the same 100 foot running diagonally across the building. I have never read whether this is true or not, but there may be some truth in it. So the next time you run up another antenna, try to keep the cable run as short as possible, never join cable lengths, never use thin cable if you can afford thick, always make a very loose loop where the cable enters the building. This serves two purposes, firstly, it stops the rain travelling up the coax and into your property. And secondly, sharp turns can cause the coax to pinch, which in extremes can cause the inner conductor to get squeezed very close to the outer conductor, this will cause a small mismatch, as the cable is no longer a constant 50 OHMS along it's entire length. ICOM R-7000 HINT I found after lifting the lid on mine, that there was a jumper marked AM wide and narrow. The factory had set mine to wide, by simply changing the jumper over to the narrow setting, I now get a better signal to noise ratio, and distant traffic seems easier to pick out of the noise. HANDHELD SCANNER BATTERIES I have found that whatever make of AA NICAD cells come with a new scanner, they are always 500MAH. I recently spoke to a salesman from SAFT batteries, and asked if there was a more powerful cell in the same packaging. He replied that they marketed 600MAH, 700MAH, and their research facility was perfecting the 1AH cell. Cap in hand I asked for some samples, duly six of the 600MAH and six of the 700MAH arrived. The difference between using the more powerful cells is quite remarkable. My YUPITERU MVT-5000 will go nine hours at an air show without failing. I therefore suggest you invest in some heavier duty cells if you are unhappy with the life of your current NICADS. A point of interest, the man from SAFT told me that NICAD technology was soon going to reach it's limit. Therefore they were now working on Nickel hydride and nickel hydrogen technology, which will allow a 1AH AA cell to be completely charged from flat in sixty minutes! THE ICOM R-1 MINI H/HELD SCANNER I know several people who now own them. I have not been tempted, mainly because size is not everything, or that's what my girlfriend tell's me! Anyway, battery life is said to be rather poor even with the battery save feature. The main gripe is the receiver front end. It has very poor strong signal handling qualities. Powerful local traffic tends to cause havoc with the R1's front end. And if you live in a town and put the scanner on an external antenna, then the situation get's worse. I hear tell that ICOM UK are working on the problem. As I know this scanner is not on sale in the USA, and as I also know that many of you wish to purchase one, I will try to get one of the owners to write you an honest revue. SHINWA A japanese radio producer, not currently exporting products to the UK or USA as yet I think. Anyway they have brought out a new scanner that is in the same case design as the rather sorry Kenwood RZ-1. The display has to be the best I have ever seen though. Lot's of different coloured LCD elements. And even a fully functioning I/R remote control. So if you are lucky enough to own a stretched Lincoln Continental and cannot reach the dash from the back seat, then this might be the scanner for you. My friends in Japan have tried one, and are less than impressed with it's sensitivity, which once again makes a great product fall flat on one of the most important facts. If your scanner can't hear it, then neither can you! WHAT'S ALL THIS 80% LARK THEN? Somebody looking over my shoulder, just asked why I kept referring to coax with this magical 80%. Well firstly, if you go and buy coax, and the black outer sheath has no manufacturer or classification printed on it, then I suggest you leave it well alone. Cable companies that produce good commercial quality cable, are only to pleased to state who made it and what it's specs are. Furthermore, the best cable has 100% screen, that is to say if you bare back some of the plastic sheath, then all you will see is a very tight and closely knitted copper braid, no white plastic insulator should show through. The cheaper (and lossier) the cable, the more white insulator you will be able to see through the gaps in the braid. So the next time you go cable hunting, forget Radio Shack, and your local C.B. shop. Instead head for a well known radio amateur supplier, ask what is the lowest loss 50 Ohm coax in your required diameter, and ask to borrow a knife so that you can examine the braid. In the UK we have a Swedish coax called POPE'S H100, it is a little thinner than usual, so if you are not very clever, the N-type plugs fall off. Apart from it's very low losses at 1GHz, it also has a very thick solid centre core, and underneath the outer braid there is a complete sheet of copper foil running the entire length. It is not the easiest coax to bend in tight loops, but remember you shouldn't be doing that anyway should you! However, pound for pound it is still a much better bet than Andrews Heliax, which if you have ever costed it out, you will know that the special connectors alone cost an arm and a leg (english slang). NEW PRODUCT An interesting new item for the cellular market has just been released over here. Suppose like me you have a portable cellphone, when you are chatting away on it in the car, much of the measly RF it generates, get's absorbed or just plain blocked by your car's bodywork. Well this new product is a passive antenna. It looks just like an on glass antenna, except on the inside of the glass is another small rubber antenna. The theory is that it picks up your signal, passes it to the outside of the car's bodywork via capacitive coupling, and then amplifies it via the 3DB gain antenna stuck onto your rear window. I think it is either a great idea or an elaborate con. If it appears to work, then it may have possibilities for h/held scanners that often get sat on the passenger seat. Because if it works one way, then surely it must work the other way as well. Certainly food for thought. And as it uses no components or power, it must be easy for anyone to install. To work well in the field of reception, I guess you would need one for lowband VHF, one for highband VHF, one for UHF and one for the CELLULAR BAND. Therefore if you have more money than sense, you could well brighten up my day by driving past my house with four assorted length on glass antenna's on your rear window. Any informed comment on this antenna theory would be appreciated. SATELLITE POSSIBILITIES Friends have asked me several times why I don't attach my R-7000 to the downlead from my satellite dish and see what I get. Well, so far I have not tried it, but I would be interested to hear from anyone who has. So if I'm talking about YOU, then why not write an article for the BBs, and let the rest of us know what's to be heard. THANKS I would like to thank John Henry who took the time to leave a message of encouragement on Howard's BBs. In fact it was John's kind words that convinced me to put pen to paper once more. It is nice to know that not only what I write is downloaded, but also appreciated. Thank's John. NEW SUBJECTS I am currently searching the old grey matter trying to think of new subjects and articles to write about. If there's anything I have touched upon that interests you, or you simply want me to write about a specific subject, then leave me a message in the mailbox section. If I know anything about the subject in question, then I will certainly knock up an article for you. Must conclude, as I have spent more time on this article today, than on work related matters. Cheers for now Nigel.