Good aerial for Icom R5

[wlm-21]

I live near the flight path to Newcastle upon Tyne airport and have used my scanner quite a lot, but now find if i am sitting with the computer on, there is too much interference to hear what's going on.

I want a simple external aerial to stick on the gable of the house ... nothing too big or expensive, just something suitable so i can listen to the 'air-talk' while computing.

Thanks in advance !

ps I sometimes pick up the Coastguard or the Tyne Harbour master, so need the aerial suitable for that too

[enicalyth]

please noooooooooo

I don't know the legalities of listening in the UK but your problem appears to be that your PC is causing RF interference and it is your duty to cease that nuisance not get a bigger aerial.

Anyway that aside a golden rule of RF is to try a quarter-wavelength whip of length 234/ frequency in Megahertz. Suppose you were listening out on 234MHz then one quarter wavelength is one foot. That length produces a characteristic impedance which must be matched into your receiver and if your receiver has been designed by any half-way decent RF engineer then the stub aerial will be a good catch-all for your frequencies of interest.

So first clean up the interference your PC is causing and make sure that there hasn't been any damage to the stub aerial connection. If performance is still unsatisfactory you can waste a lot of money trying this and that wunderkind antenna so if there is an Amateur Radio Society in your area, ask for advice.

Suppose still no go. Well you can build an antenna booster for $10. Riffle through the pages of "A Practical Introduction to Electronic Circuits" by Martin Hartley Jones and you'll find his little common-base amplifier. Any one can build it though a friend in amateur radio will make a better job and knowing what you are listening to adjust Hartley-Jones component values to suit. Just adding one thing for that friend. The characteristic impedance of such an NPN transistor, looking into the emitter is 25 / IE where IE is the emitter current in milliamps. Thus if your friend suggests a different aerial impedance, adjust the emitter current according to this rule of thumb.

If your reception improves then job done. If it doesn't then where you live is exceeding the capabilities of your little receiver and no aerial is ever going to cure your problem.

Best of Luck

The "e"

[wlm-21]

Thanks for your detailed reply, although not being a real fanatic, some of the jargon went over my head a little

I listen to the following frequecies :-

119.700
124.375
156.000
156.600

Would you be able to show me a link of the type of aerial which would be best. I obviously wouldn't buy it from Australia, but I could look at the specifications and get something similar in the UK

thanks again !

[magpienja]

Hi there when you say cheap? I made my own or do you prefer a shop bought one,

These work fine and handy if you have a steel gutter on the house to mount it on,

TAXI MAG MOUNT AERIAL on eBay (end time 17-Dec-09 13:36:27 GMT)

I would presume the further away from the PC the less interference you will get.

Nick.

[HEATHROW DIRECTOR]

Given that taxis do not operate in the airband I would not waste £15. A simple vertical dipole made of wire would help and cost pence... Remember that small scanning receivers are compromise radios and if you attach an outdoor aerial you may swamp the radio with unwanted signals.

As already suggested, clean up your PC so that you get no QRM.

[frostbite]

All PCs (and a lot more besides these days!) put out 'birdies' on various frequencies. Some you can suppress, some not. They're only short range, but of course your kit is in range.

Look out for a 'slim jim' aerial (which you can also make yourself). It's basically a half wave dipole over a 1/4 wave stub. The amateur band 2m one should do nicely for you as it's tuned (for transmitting) roughly dead centre of the frequencies you mention.

[magpienja]

HEATHROW DIRECTOR yes of course you are correct about the taxi/air airband freq,

I suggested that antenna as it would no doubt come with a longer whip than req for airband use, its then a simple job to cut to the req length, but on rx length is not as important as it is with tx as I am sure you know,

But I think WLM-21 also likes to listen to marine traffic being around the 156mhz section of the spectrum, so I think that antenna would be a good compromise.

Nick.

[frostbite]

The taxi band is a higher frequency than either of those wanted by the OP, so an aerial intended for that use would be shorter than ideal for him.

[magpienja]

Not enough to matter on RX, anyway the add does state can be trimmed to suit your req freq, and your plug choice, no doubt he will put a cable on to suit your needs, sound ok to me for £15.

Nick.

[wlm-21]

Thanks everybody for your replies

I'll get a 2m slimjim and hope that does the trick.

Kind regards !