BMW K bikes (Bricks)

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1Back to top Go down   AM/FM Radio Antenna  Empty AM/FM Radio Antenna on Tue Nov 03, 2015 5:27 pm

floyd

floyd
Life time member
Life time member
Howdy Krew,

This isnt a K question as such....but its an accessory fitted to my K so good enough Wink

I have a marine stereo installed on my bike. It plays digital files from a USB stick, and it also has an AM/FM radio. I really like listening to the radio - particularly all flavours of the ABC.

Anyways, I have never been able to get the radio to pick up a good signal. I have a rubberised bendy antenna installed on the front fairing. The radio will only get a clean signal if I am touching the antenna's cable. 

Do I simply need to ground the antenna? Perhaps its designed to go through a car roof and be grounded on the sheet metal? I did try earthing it with a bit of wire but no luck. It was a bit of a half ass attempt though, using what I had on hand at the time....

Anyways, hoping one of our electro-gurus will point me straight. 

Cheers all,

Floyd


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K100 with lots of K1100 bits - mongrel of a thing...
    

2Back to top Go down   AM/FM Radio Antenna  Empty Re: AM/FM Radio Antenna on Tue Nov 03, 2015 5:39 pm

indian036

indian036
Life time member
Life time member
Stretching my limited memory of radio basics, the antenna usually requires a "ground plane", which is more than just a wire. 

As you say, in the old days, the metal of the car roof or mudguard did this job. I've also seen a 1ft square piece of metal under the roof of a fibreglass half cabin boat which has the aerial attached through the middle. 

I've not experienced a radio on a bike, but given the fairing being available, I'd be inclined to put a piece of thin aluminium sheet behind it, more or less centred on the aerial mount and grounded to it. Aluminium because it won't rust and can be easily shaped and cut to fit the curves of the fairing. 

Interested to read contributions from people with more expert knowledge or better memories. 

Bill


__________________________________________________
1985 K100RT  VIN 0028991  My original Very Happy   (Historic rego)
1985 K100RT  VIN 0029036  BOB the Blue Old Bike  (Historic rego)
1990 K100LT  VIN 0190452  Work in progress
1984 K100RT  VIN 0023022  Work needing lots of progress

1986 K100RT  VIN 0090542  Work needing lots and lots of progress
1993 K1100LT  VIN 0183046  Work in progress
1993 K75S  VIN 0213045  Newest toy, slightly non-original
    

3Back to top Go down   AM/FM Radio Antenna  Empty Re: AM/FM Radio Antenna on Tue Nov 03, 2015 8:55 pm

K75cster

K75cster
Life time member
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The R100rt Fairing I had on the K75c when I bought it had an CB aerial on the right side and a radio on the left it was one of those short rubbery ones with a pivot point at the attachment to the fairing so it would point up, my radio was above the instrument binnacle so maybe it provided a ground plane effect that way, it did have an earth wire to the frame though and worked a treat. I went through a heap of them plane car radios from the wreckers, one day though I'll invest in a marine radio so as to keep them for more than a year or so.


__________________________________________________
Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt 1992 K1100LT a blue one

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

4Back to top Go down   AM/FM Radio Antenna  Empty Re: AM/FM Radio Antenna on Tue Nov 03, 2015 9:28 pm

RicK G

RicK G
VIP
VIP
You don't really need a ground plane for good reception it's only necessary for transmission of radio signals and even then you can get antenna that dont need a ground plane but they are usually only for the UHF CB.
Usually if you get a big improvement in signal by touching the antenna it means you are a good antenna. To explain it would take around 10 pages and boredom would kill you.
It is quite possible that the radio need a strong signal and that wont happen unless you are near the transmitter. Maybe tie a real long bit of wire to the antenna and let it fly in the wind. Rolling Eyes


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

5Back to top Go down   AM/FM Radio Antenna  Empty Re: AM/FM Radio Antenna on Tue Nov 03, 2015 10:02 pm

charlie99

charlie99
VIP
VIP
your little rubber duckie type antenna is the issue Floyd

from memory all of about 3 inches of them actually act as an antenna ....have you tried a automotive type antenna (after market type ) the ones that are about 300 mm  long and extend ?


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OAM/FM Radio Antenna  Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

6Back to top Go down   AM/FM Radio Antenna  Empty Re: AM/FM Radio Antenna on Fri Nov 06, 2015 7:44 am

floyd

floyd
Life time member
Life time member
Thanks gang

Ill try a big arse wire antenna soon and see how it goes


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

7Back to top Go down   AM/FM Radio Antenna  Empty Re: AM/FM Radio Antenna on Fri Nov 06, 2015 8:58 am

AL-58

AL-58
Life time member
Life time member
I have an original BMW K100LT aerial available if you want to try. Rigid, maybe 18" long (dont like to brag though)

Al


__________________________________________________
'87 K100RS/HRD sidecar (1100 motor)  sc25 
'92 K100RS-16v (Paint it Black)

'87 K100RT with Paralever backend

"When I'm too old and too foolish to handle a sidecar I'll buy a Sportsbike"

AM/FM Radio Antenna  K-dogs10
    

8Back to top Go down   AM/FM Radio Antenna  Empty Re: AM/FM Radio Antenna on Fri Nov 06, 2015 9:35 am

floyd

floyd
Life time member
Life time member
@AL-58 wrote:I have an original BMW K100LT aerial available if you want to try. Rigid, maybe 18" long (dont like to brag though)

Al

lol! AM/FM Radio Antenna  44271  SO i should take 3" off that to get an accurate measure? Still rather 'generous' in proportions.

Thanks for making me aware there was a stock BMW item for this. didnt even consider it. According to the diagram there is a thick-ish earth strap-on. Might give that a try on my 12" floppy rubber member and see if i can induce a response. 

AM/FM Radio Antenna  B0002140


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

9Back to top Go down   AM/FM Radio Antenna  Empty Re: AM/FM Radio Antenna on Fri Nov 06, 2015 5:31 pm

AL-58

AL-58
Life time member
Life time member
Didnt notice the earth strap, but then the RT is ex police and there are additional earth straps everywhere (I cut them off whenever I find them, just a nuisance)

Al


__________________________________________________
'87 K100RS/HRD sidecar (1100 motor)  sc25 
'92 K100RS-16v (Paint it Black)

'87 K100RT with Paralever backend

"When I'm too old and too foolish to handle a sidecar I'll buy a Sportsbike"

AM/FM Radio Antenna  K-dogs10
    

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