• scanhint

    From LU9DCE@21:5/101 to BBSRT on Wed Jul 3 02:40:06 2019


    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.






    --- Mystic BBS v1.12 A43 (Linux/32)
    * Origin: HAMRADIO telnet lu9dce.dynu.com (21:5/101)