rwmorrisonjr

I've installed an Alpine CDA-9085 head unit in place of the factory head unit, and the radio reception is below that of the OEM unit! At first I thought that it was because I didn't hook up the diversity antenna, so I bought and adapter & "Y" cable to hook both antennas into the head unit, no improvment. So I disconnectd the power antenna and voila! the reception improved. It seems as though I'm getting a bad ground or something from the power antenna that is impairing reception. I don't think its the head unit itself since it works fine, but am not entirely sure. Has anyone had these type of issues also? If so was it the radio or the antenna? Would this be fixed by eliminating the power antenna altogether or by replacing it with a whip antenna, a la the Tacoma antenna mod? Or should I just get XM and forget about it all together?

Andrey

Unless I missed something, but I never knew that there is an adapter out there which would let you connect both power and diversity antennas... Where did you get that adapter what kind of adapter that is?

-- Andrey

rwmorrisonjr

I bought a GM barbless (mini-Motorola plug) to full size Motorola adapter and then plugged that into the Y-adapter.

Andrey

Have you tried connecting just power antenna without any adapters?

-- Andrey

midiwall

I don't think that'll work... By connecting the two antennas in parallel, you're cutting the impedence in half and creating an interesting capacitance issue.

The head unit has to be made to be able to electrically mix between two antennas, or the antennas have to be electically matched and tuned to be able to work in a "Y"'d configuration.

The stock head unit doesn't see both antennas at once. It works to build the best signal it can from looking at what's present on the antennas and then using each to cancel out artifacts like noise and phase distortion caused by reflections off of buildings.

fwiw, I had the same issue when I replaced my stock unit many years ago with a Sony Xplod. I got "better" reception by going to a FM Firestik, (http://www.midiwall.com/4Runner/firestik.html) but I've never gotten it back to the point that it was with the stock head unit.

What I eventually did was install XM radio - and I haven't used the FM radio since. (about 7 months now)

Andyman

Hey, just a quick thought... Sometimes the antenna connection is pretty stiff, maybe it's not in all the way? Not to insult you... I have done this once... and you only ever do it once...

rwmorrisonjr

I've tried the power antenna alone and the reception is terrible. Granted, I do listen to talk radio so AM can be somewhat squirrly but I'm also having issues on FM. The stock radio was awesome and I think that's because it was made by DELCO, and they put a lot of research into the AM/FM portion of their units, especially due to thier demographic research (ie old people listen to the radio more than tapes/CD's). The radio actually seems to get better reception with the diversity antenna alone than with the main antenna mast. And yes, I have pushed the plug all the way in. I don't want to go with the FireStik antenna as I know I'll drive through a garage be off road & do some damage, that's why I was thinking the Tacoma whip antenna.

As for XM, my Alpine unit is equipped for XM, but I need to buy the receiver unit and a subscription. Since we're saving for a wedding and getting out of debt over here, those are some toys I'm not buying right now. Plus I'll be flying around the country so I won't be using the XM right now. But I am going to get it when the money comes more into line.

Does anyone know how to disable the factory power antenna so it will stay down? I can't pull the TWO fuses that Toyota uses for power w/o disabling half the truck!

Or should I just go back to the OEM head unit & find a new place for my CB? ARRRGGGHHHHH!!!!!

waskillywabbit

iTrader: (-1)

Time for a Taco whip antenna mod!

rwmorrisonjr

That or unplug the power antenna and use the window one, no antenna sticking up at all!

Henryv

Um can you clip the antenna lead wire in the stereo's harness? I think that would make the antenna not go up. I also just replaced my deck and have the same problem. Its not too bad but like you said, the reception is not as good as the stock stereo. I dont know what it is either because it can pick up the really strong signals clearly but the weaker ones are less than clear.

rwmorrisonjr

I'm just going to go ahead & do the whip antenna mod, am tired of the power antenna anyhow (always thought they were usless) and it was wiggling a bit in the wind today, so time for it to go. Have the parts on order & will be here next week for a weekend install.

waskillywabbit

iTrader: (-1)

Bob has a good write-up and I have done one based on his trial & error

rwmorrisonjr

Am going to use both write-ups and eliminate this crappy power antenna once & for all! Glad you both have good write ups out there. Your part numbers were right on, the guy out here was able to find them right away. They cost a little more, about $120 w/tax, but then this is Colorado and things are more expensive here. Have the mast and grommets in my garage, waiting for the mounting unit to come in next week.

waskillywabbit

iTrader: (-1)

I think this was one of my favorite mods. Not a lot of brass and flash to it, but it adds a nice touch of "silent" and "hidden" style to the rig and adds a touch of ruggedness compared to the elegance of the power antenna. No more worries with that power antenna getting whacked by a low hanging tree limb!

Good luck!

rwmorrisonjr

I was actually going to try & get away with using the glass mounted diversity antenna and just disconnecting the power one completely, but the reception wasn't that great with the diversity one either. If it had worked, that would have been a better mod b/c then I would have had a stealth antenna. Oh well, the simpler the better.

terryjmatthew

Did anyone ever find the reason for this? I just installed my Sony HU and am having the same problem. I would like to keep using my power antenna if possible.
Any help would be appreciated.