FM Band Expander and Aerial Booster

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Goosey

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#79709 21-Mar-2011 18:20

Hi there,

About to fit an aerial booster to my VW Passat (1999).
The factory fitted blaupunkt radio is about to be replaced by a pioneer head unit ( as the factory stereo needs a key card much like a sky smart card).

Anyhow, removed the factory radio and found the two plugs (yes I have a harness to convert these two plugs to my new head unit)...however I noticed the aerial cable has a band expander fitted (inline)....BUT a small black wire runs from this band expander to one of the pins on the factory plugs. Am I correct to assume this is the ground for the band expander???

Can I plug the aerial booster in before the band expander and then use them together??
Ive been told to remove the band expander and just use the booster....but what would I do with this black wire?
Id say it would be ok to 'chop and terminiate it' (and yes id leave sufficent length if I ever needed it again).

Thoughts?

Goosey

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#450446 21-Mar-2011 18:23

Forgot to mention, the new head unit hasnt arrived.... so cant just plug in and see what happens to the FM and AM bands without fitting the booster and subseqently cant see what happens if I remove the band expander and just use the booster.

SepticSceptic

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#450635 22-Mar-2011 09:55

That wire should be the +12v for the expanders electronics. 0v, or gnd, would be done thru the coax screening, which is terminated at the head, or the aerial. Or both.

Remove the expander, as it could have an insertion loss of a few db ( not always though - depends on the quality)

Jaxson

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#450641 22-Mar-2011 10:11

As above. The band expander needs power and it gets it through that cable. Do you have simple test gear, even a lamp test unit?

You won't need a band expander on a NZ new head unit so it can come out altogether, or you wont get any stations with the new one.

I'd personally test the new unit without an aerial booster if you are adding one of these yourself. If there is one in the car already then leave it in there.

richms

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#451247 23-Mar-2011 21:47

The car probably has a booster already, some are powered via the coax cable which is often a problem with band expanders.

There should be no need to fit an aftermarket booster to any stereo made this side of the 1970's or in a factory not in shenzhen and direct selling on the internet.

The fact you have a band expander means that the factory system was designed to recive only to 90MHz and the factory boosters on most cars have a very sharp cutoff, so even with the proper headdeck instead of the abortion of a result that a band expander gives, you still get pretty crap response at the top end.

eg, mums hyundai will get upfm perfect all the way out to papaptoetoe etc, my skyline with the glass mount antennas craps out about mt wellington when going south. If I put a few m of wire in instead of an antenna (as I did before I had the loom adapter) it actually works better than the in glass ones.

Richard rich.ms

Goosey

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#451259 23-Mar-2011 22:16

Hey Guys, thanks for the posts.

Installed the deck this evening...removed the band expander (or was it a booster)?
Fitted the new head unit with supplied connectors and attached the new booster.

FM freq such as 88.6 worked fine and the other end 107-108 picked up something also.

HOWEVER, i keep losing the memory... then discovered the 4 wires for power/earth/remote may have been wired to the connectors incorrectly. Id say because I have power and the head unit works...the wire to the battery is in the wrong slot and going nowhere from the head unit and/or the remote wire that susposed to goto the booster.

Im trying DSe tomorrow (as its handy to my work), to see if they sell the tool that you can remove the wires from these connectors with. I really dont want to chop my wires off the connector for the sake of tidyness etc etc .

I guess im getting old... all this stuff was 1st nature back 'in the day'.

Right thats the stereo almost done... time to look at tints and new rubber !
Cheers
Goose

richms

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#451260 23-Mar-2011 22:18

There are 2 standards on how the iso looms are wired for the power and accessory. most of the adapter looms have them connected to bullet plugs so you can swap them over as needed, but when you have a headdeck with the iso plugs on it already there is usually no ability to swap them over, You should be able to eject the pins from the plug if you poke the spring down with something like a pin and swap them over, the pinout for iso plugs is easily googleable to know which to switch.

Richard rich.ms

Goosey

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#451262 23-Mar-2011 22:27

richms: There are 2 standards on how the iso looms are wired for the power and accessory. most of the adapter looms have them connected to bullet plugs so you can swap them over as needed, but when you have a headdeck with the iso plugs on it already there is usually no ability to swap them over, You should be able to eject the pins from the plug if you poke the spring down with something like a pin and swap them over, the pinout for iso plugs is easily googleable to know which to switch.

Hiya, thats what im trying to do (eject the pins at the car connector end)...correct me if im wrong, there will be two little 'fins' on each side that I need to squeese down from the end that has the wire right? (i.e. depress them and pull... hard work so far...i could do with 2.3mm tweezers !

If all else fails... i might have to sacrifice and do the CHOP and JOIN ! GRRRR.

Goose

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richms

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#451264 23-Mar-2011 22:32

Yeah, they are pricks of plugs to eject since they dont have holes for the catch to be visible in. I dont have one here with me to remember how to do it, but I know I used 2 of the dollar store hairclips to do it when I did.

Richard rich.ms

Goosey

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#451266 23-Mar-2011 22:38

richms: Yeah, they are pricks of plugs to eject since they dont have holes for the catch to be visible in. I dont have one here with me to remember how to do it, but I know I used 2 of the dollar store hairclips to do it when I did.

good point... theres one of those stores near the DSE.
I running out of patience..... maybey this time tomorrow... its the good ol chop and connect via connector strip going to happen... mind you I do have a pen gas torch ! however I value the plastic trim in the small space I have !

Goose

Jaxson

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#451347 24-Mar-2011 10:10

Ha the joys of a set loom. I seriously much prefer to cut and reconnect directly as it's usually cheaper. Takes a bit longer for sure but that's just me.

There are two power supplies to a head unit. One is a low current always on connection for the memory/stations etc, and the other is the higher power ACC connection that comes on when the key is connected and runs the actuall stereo/amplifier internals.

Stick a clip on glass light stick thing or a multimeter into the connectors and you can usually fairly quickly work out which lead is which as you turn the key on and off. One glows all the time and the other is key connected.

Goosey

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#451514 24-Mar-2011 16:20

Jaxson: Ha the joys of a set loom. I seriously much prefer to cut and reconnect directly as it's usually cheaper. Takes a bit longer for sure but that's just me.

There are two power supplies to a head unit. One is a low current always on connection for the memory/stations etc, and the other is the higher power ACC connection that comes on when the key is connected and runs the actuall stereo/amplifier internals.

Stick a clip on glass light stick thing or a multimeter into the connectors and you can usually fairly quickly work out which lead is which as you turn the key on and off. One glows all the time and the other is key connected.

Cheers, yeh Ive wasted time and energy trying to do it properly, if I dont suceed this evening using hairclip/paperclip... im grabbing the wirestrippers and chopping.

Had enough of re-programming audio quality and radio presets.

Thanks all for the conversation.