Weird Power Antennae Behavior

[bwoods]

On my '96 LS400, whenever I press the radio preset 4, 5, & 6, the power antennae goes down about 1/2" to 3/4". When I press preset 1 - 3, the antennae goes fully up. This is weird. Anyone knows why it is doing this?

On a different note, the night time backlight for presets 5 & 6 is dead. Is this something replaceable and easily fixable?

Thanks,

Brad

[AzHotLS]

You have more than one antenna? I'd like to see pics. B)

What you're experiencing is normal. I don't know the exact reasons why but mine does it too. Google "antenna length" if you really want to know.

For the backlight issue, since it's just a couple buttons, it's more difficult. Try doing a search to find threads talking about this, I know they're here somewhere.

[killerFatty]

I believe Lexus and their infinant wisdom decied to make the antenna adjust to the strenth of the radio station. So its normal behavior.

[bwoods]

You have more than one antenna? I'd like to see pics. B)

Oh, jeez...wasn't that dumb of me? I guess it shows how many times I've typed the word "antenna" in my life! (Guess that rules out entomology as a career choice!)

What you're experiencing is normal. I don't know the exact reasons why but mine does it too. Google "antenna length" if you really want to know.

For the backlight issue, since it's just a couple buttons, it's more difficult. Try doing a search to find threads talking about this, I know they're here somewhere.

Thanks for letting me know it's normal. I just never noticed it before.

Re: searching on buttons: OK, I'll give that a try. Sometimes it's so difficult finding info in this forum searching threads...but OK, I'll do it.

Thanks!

[bwoods]

I believe Lexus and their infinant wisdom decied to make the antenna adjust to the strenth of the radio station. So its normal behavior.

OK, thanks! That is feature overkill, yes?

[bwoods]

You have more than one antenna? I'd like to see pics. B)

What you're experiencing is normal. I don't know the exact reasons why but mine does it too. Google "antenna length" if you really want to know.

For the backlight issue, since it's just a couple buttons, it's more difficult. Try doing a search to find threads talking about this, I know they're here somewhere.

BTW, I am laughing at your avatar...we are moving to Tucson this July/August. We live in the very hot Central Valley of CA, but I know Tucson is going to be slightly hotter. Cooler than where you live, though, I hope.

[oldskewel]

...

On a different note, the night time backlight for presets 5 & 6 is dead. Is this something replaceable and easily fixable?

...

I had the exact same problem on 3+4 on my '91 with the Pioneer stereo. Fixed it last weekend. Not especially easy. Soldering required. Here's what I can remember:

- Remove stereo:

-- remove flat wood panel around gear shift. Pry up at rear, then pull backwards (towards rear of car)

-- remove ash tray module

-- remove vents above stereo

-- you'll see 2 bolts/screws above and 2 below the stereo. Remove them and remove stereo, unplugging electrical connections.

- Disassemble components

-- some screws on the side to separate the frame from the climate control + stereo

- Take front cover off stereo

- See which of the light bulbs goes to 5+6. It is soldered to the board, so remove and replace with a new one. I don't know what wattage it is supposed to be, but I just used a spare generic one I had from Radio Shack. Turned out to be not as bright as I needed, but OK. It was a perfect size fit though. I think this is the one I used: 12V Microlamps (2-Pack) $1.79 Model: 272-1092

(If I were more careful, I would have un-soldered one of the working lights, checked its resistance [can't do it while on the board since it's wired in parallel, many other circuit paths] and replaced all the lights with the properly sized ones while I was there. If one burns out, the others are probably close behind since they all see the same work load.)

If you do all this, you may as well double check all lights before taking things apart, since most of the work is getting to the bulbs.

[Willemh]

The antenna length depends on the frequency, at 88mhz it have to be 86 cm at 107mhz it have to be 70 cm Lexus adjust the antenna length automatically. If you program your stations other, the length changes with the frequency not the preset button.

The higher the frequency the shorter the antenna length. (look at the short cellphone antenna's =900mhz)

Car antenna's are quarter wavelength antenna's ... they told me...

B)

GReeTZ Willem

[bwoods]

The antenna length depends on the frequency, at 88mhz it have to be 86 cm at 107mhz it have to be 70 cm Lexus adjust the antenna length automatically. If you program your stations other, the length changes with the frequency not the preset button.

The higher the frequency the shorter the antenna length. (look at the short cellphone antenna's =900mhz)

Car antenna's are quarter wavelength antenna's ... they told me...

B)

GReeTZ Willem

Thank you, that is fascinating information. That means that Lexus is even more luxury high tech that I thought!

[oldskewel]

The antenna length depends on the frequency, at 88mhz it have to be 86 cm at 107mhz it have to be 70 cm Lexus adjust the antenna length automatically. If you program your stations other, the length changes with the frequency not the preset button.

The higher the frequency the shorter the antenna length. (look at the short cellphone antenna's =900mhz)

Car antenna's are quarter wavelength antenna's ... they told me...

B)

GReeTZ Willem

Yes, theory calls for optimal efficiency with an antenna that is 1/4 wavelength long, assuming there is a reflecting ground plane. 3e8 m/s / 107.9 MHz * 1/4 = 69.5 cm. And there may be a 5% reduction due to the velocity factor - that wave propagation in the antenna is slower than the speed of light in a vacuum (300,000,000 m/s) by this much.

I was surprised to hear of this, so I checked my '91 LS400 with the Pioneer system. Turning it on in Tape mode, the antenna stays down. Turning on the radio, here's what the antenna does (measured along the length of the antenna pole itself, not the base, but including the tip):

AM: 98.7 cm (AM is much lower frequency, so longer wavelength, so as long as possible would basically be good)

FM at 95.9 MHz and below: 83.8 cm (same fixed height from 87.9 MHz through 95.9 MHz)

FM at 96.1 MHz and above: 75.3 cm (same fixed height from 96.1 MHz through 107.9 MHz)

Checking the switch frequency: 95.9/96.1 MHz:

3e8 m/s / 96 MHz * 1/4 = 78.1 cm, which is in between the 75.3 and 83.8 cm actual lengths. There is no accounting for a velocity factor here.

Kind of cool as long as it works, I guess. Feature overkill? Definitely.

[bwoods]

I had the exact same problem on 3+4 on my '91 with the Pioneer stereo.

Thanks for this great post. I have the Nakamichi. Wondering if it would be similar.

[Larry W]

On my '96 LS400, whenever I press the radio preset 4, 5, & 6, the power antennae goes down about 1/2" to 3/4". When I press preset 1 - 3, the antennae goes fully up. This is weird. Anyone knows why it is doing this?

On a different note, the night time backlight for presets 5 & 6 is dead. Is this something replaceable and easily fixable?

Thanks,

Brad

Brad:

Its normal. My 94 LS does the same thing.

[AzHotLS]

BTW, I am laughing at your avatar...we are moving to Tucson this July/August. We live in the very hot Central Valley of CA, but I know Tucson is going to be slightly hotter. Cooler than where you live, though, I hope.

You'll feel right at home in Tucson then, the lower humidity should make up for the higher temps. Correct, Tucson is about 5 degrees cooler than the metro Phoenix area.

Yeah, I think my avatar is pretty cool. I don't remember how hot it was the day I took the pic, near 115 I believe. The car was sitting in the driveway in full sun when I took the it. So radiant heat from the concrete helped drive up the temp.