Antenna problems

[JMertz]

After reading about this option here, I installed the Jensen Heavy Duty radio with bluetooth on my 07 RT. Works well except I don't get any AM reception. I was told that if you don't get AM, your antenna isn't working correctly. I have a standard 31" whip antenna, not amplified or powered in any way, mounted next to the license plate. Cord didn't reach so I had to use an extension. I don't know a lot about antenna electronics but I know some antennas need to be grounded - this one is not but I don't know if that makes a difference. Picks up FM stations pretty well though not crystal clear.

 

Any advice on what I might have wrong in the setup? Do I need a different type of antenna?

 

Thanks,

 

John

[AnotherLee]

John - have you tried to connect the antenna without the extension? (Just as a test)

[kgerry]

AM reception is critical to a good antenna source, whereas FM you can usually pick up without an antenna even plugged in (although it will picketfence a fair bit).... try another antenna plugged into the radio and see if it works... if it doesnt you likely have a bum AM front end in the radio or blown AM tuning FET's.....

[upflying]

It sounds like the antenna needs to be grounded to the bike.

Here is a photo of how my antenna is mounted for my Jensen radio.

That plate is the former communications antenna mount when this was a CHP bike. That mount is grounded to the bike.

The antenna is just a cheapie car radio setup. I also had to plug in an extension because the cable was too short.

[JMertz]

Nice looking setup. I'll try better grounding and see if that works.

 

Thank you,

[lkchris]

Here's a bit of not useful but maybe interesting info: the silly looking mounting of the OE R1200RT antenna on the front of the fairing presents virtually no problem fitting the BMW OE bike cover.

[JMertz]

Update: I have mounted a 31" whip antenna and have grounded it to the frame well (good continuity checks, 100% ground against battery positive). What I have now is a LOT of ignition noise. It starts as soon as I turn the key, bike not running. Bike running does not make it any worse. Radio is powered through an Eastern Beaver fuse block, which is itself powered directly off the battery with relay tapped into the tail light.

 

Any thoughts on where the noise is coming from and how to deal with it?

 

John

[upflying]

The noise is coming from the fuel pump.

An ignition suppressor might be needed.

Is the reception any better?

Any tornado damage last night?

http://www.crutchfield.com/S-ivhm5JpV6tb/learn/learningcenter/car/noise_suppressors_installation_guide.html

[kgerry]

as a rule the ground plain for an antenna is used for noise rejection, has nothing to do with signal strength... the inverse can apply whereby you can pick up a lot of radiated noise thru the ground path if it's there... i mount antennas on bikes and boats all the time without worrying about grounding them...

 

try ungrounding the antenna and see if your noise goes away... then you just have a signal strength issue to deal with... as suggested try another antenna just laying on the seat etc plugged into the radio, does it get good reception? then you have a bum antenna... is it the same as before? then you have a bum radio.... the Jensen Industrial units are not a great quality (i used to sell them)and are fairly suceptible to ESD damage... especially on AM (especially on tractors)

[JMertz]

Thanks for those quick replies. Ungrounding the antenna worked! Thank you!

 

So now I'd say I have reception that is good on FM, pretty good on AM, meaning I get lots of stations, but with hiss. Sounds like regular AM hiss like I used to hear on car stereos sometimes (in the old days, when you actually used to be able to put your own unit in a car).

 

I have both a rubber ducky and whip antenna. Switched them and both seemed about the same, slightly better reception with the whip, but both have same amount of hiss.

 

So, now I know I don't want to ground these particular antennas, but I could still try to get a more solid signal, perhaps with a different type of antenna. Maybe a no-ground-plane antenna, or is that what I effectively have now that I'm not grounded to anything? Or is there an entirely different type of antenna that might give a stronger signal?

 

I've heard that the amplified antennas make whatever noise you have louder, but do not strengthen the signal. Doesn't seem like that would help.

 

Making progress...any more suggestions welcome.

 

Thanks again

[JMertz]

Oh yes, and no tornadoes around here yet. One really big elm tree fell on a house not far away but was strangely localized - nothing around that particular house looked like it had even been blown around. I feel for those guys in OK.

 

John

[lkchris]

I probably way off here as I know nothing about antennas, but I'd still venture the factory antenna mounted on the plastic fairing might be less likely to be grounded than one mounted on a metal bracket. Do you have plastic washers?

[upflying]

I probably way off here as I know nothing about antennas, but I'd still venture the factory antenna mounted on the plastic fairing might be less likely to be grounded than one mounted on a metal bracket. Do you have plastic washers?

Could be, my lack of knowledge comes from Corvettes and antennas. I thought I recalled reading somehwere they had to be grounded.