Let's Talk Car Radios...

[RadioFixerCLE]

I have a basic AM/FM analog tuned radio from a 1989 Ford Crown Victoria.

How are those for performance? Now I just have to find a car to put around the radio. ;D

 

[boiseengineer]

Been pleasantly surprised with the rear side-window antenna and stock radio in the '06 Forester. AM's are listenable out to their .05 mV/m with no electronics noises. AM audio quality is ok. FM blends too soon but sensitivity is good.

 

[Tom Wells]

What I'm seeing I think is less a problem with radio sensitivity than unpeaked/untrimable AM inputs which kills efffective sensitivity,
and on the other hand all the vacuum flourescent displays, data bus, engine control system, all poorly shielded/bypassed.

I rented a Cadillac about 1994 which clearly had a grounding problem, but couldn't even hear "mid-strength"
signals above the noise of the dash display and even the radio's own display noise. Must have been a broken shield on that one.

You can't listen to chamber music in a boiler factory.......

on the other hand, the noise of high-voltage spark distribution has been suppressed for many years.
This is why I don't think the auto engineers are trying very hard to keep extraneous control noises out of the AM in cars.
They should all have to draw Thevenin circuit diagrams to see why their devices' current can't help but modulate the incoming AM signals.
Arghhh!

 

[tomservo]

Is it one of those Monsoon radios?

Yes, a Monsoon.

Could it possibly be a software glitch instead of directly temperature related?

I've got a (software based?) Monsoon in an '05 VW that periodically will screw the pooch on AM. It seems to get knocked off center by only ~5 kHz, enough to make everything annoyingly distorted. For a while the FM antenna amplifier would quit working on hot days, likely due to the stubby antenna's grounding coming lose in the heat.

It's actually a decent radio for AM, except that the stronger the signal, the more it rolls off highs. When I tune in KNOE from Monroe, LA (540, 5kW, 130 air miles) it has more upper end "oomph" than the local stations whose sticks I can see...

Those wacky Germans... :

 

[Tom Wells]

Is it one of those Monsoon radios?

Yes, a Monsoon.

Could it possibly be a software glitch instead of directly temperature related?

I've got a (software based?) Monsoon in an '05 VW that periodically will screw the pooch on AM. It seems to get knocked off center by only ~5 kHz, enough to make everything annoyingly distorted. For a while the FM antenna amplifier would quit working on hot days, likely due to the stubby antenna's grounding coming lose in the heat.

It's actually a decent radio for AM, except that the stronger the signal, the more it rolls off highs. When I tune in KNOE from Monroe, LA (540, 5kW, 130 air miles) it has more upper end "oomph" than the local stations whose sticks I can see...

Those wacky Germans... :

The rolling off of highs is a very common and very-hard to avoid consequence of AVC action.
If mfrs gave us RF gain and AF gain separately you would be able to listen to those locals in the same wideband glory.
When I want to hear wideband AM broadcast reference I use WSM 650 or CJAD? AM 860.
They are medium strength enough to keep amazing high-high end response despite AVC action, and locals don't sound as crisp.

If you install a flush-mount retractable electric antenna with a manual raise/lower switch, you will have this!
My buddy's 55 Oldsmobile had this, and with the incredible sensitivity of the tube radios of the day, the antenna height was
an incredibly effective RF gain control.

I monitor my pt 15 AM with a 1962-ish tube/transistor hybrid by Bendix. I find I must reduce coupling to avoid high-end rolloff.
That said, the response designed into this radio clearly would support 15kc fidelity.
It is even better than the 1966 AM/FM Bendix in another car, or the two 1972 AM/FM Motorolas (all of these modified for more highs).
Unmodified, it is almost too crisp! It has some funny 3rd harmonic distortion accounting for this, but as it is only
from the pwr output Germanium AF stage, it is oddly pleasing.

I will consider wiring to this detector for the next ( No. 11 ) podcast of Wideband detector AM 1620.

 

[kevtronics]

The factory radio in my dad's 2002 VW Golf seems to have variable AM bandwidth based on signal strength... stronger = wider, up to 6 kHz. But sometimes if a signal gets weak, it narrows down, and stays narrow, even if the signal improves again. That can be rectified by switching to FM and then switching back to AM, which causes the AM tuner to revert to its widest bandwidth, before adjusting to the current signal condition.

Also... with the radio on, hold down the MIX button for about five seconds to enter a Factory Service Test mode, with various info displays (including a signal strength meter) that can by cycled by tapping MIX. You can tune the radio and switch bands while remaining in this mode.

 

[tomservo]

The factory radio in my dad's 2002 VW Golf seems to have variable AM bandwidth based on signal strength... stronger = wider, up to 6 kHz. But sometimes if a signal gets weak, it narrows down, and stays narrow, even if the signal improves again. That can be rectified by switching to FM and then switching back to AM, which causes the AM tuner to revert to its widest bandwidth, before adjusting to the current signal condition.

Also... with the radio on, hold down the MIX button for about five seconds to enter a Factory Service Test mode, with various info displays (including a signal strength meter) that can by cycled by tapping MIX. You can tune the radio and switch bands while remaining in this mode.

I love that test mode.

Anytime the radio's on, I set it to the signal strength meter. The full range on FM seems to fall almost totally within a station's 60 dBu contour (going by FCC maps, anyway). It'd be nice to know the actual dBu, but it's a neat toy nonetheless. As for AM, I can't begin to fathom what kind of scale it's on...

What I can't figure out is one of the displays for FM that says something like MP: [0] ADJ: [0]. The numbers fluctuate depending on what the audio carrier is doing and signal strength. It's a mystery! ???

I've tried flipping from AM to FM to AM, and while the bandwidth temporarily opens up, it still seems to fall back down to a narrow setting on strong stations.

 

[kevtronics]

My guess is that "MP" has something to do with "MPX" (the FM Stereo system) and "ADJ" has something to do with the measured level of adjacent channel interference. My hunch is that "MP" is showing the amount of stereo blending (low number = full stereo, high number = blended all the way to mono), but it's been a while since I had a chance to use that VW radio.

There's a glitch, too: the test mode displays "STEREO" even on mono FM signals. Meanwhile on AM, that mode offers the radio's analysis of whether the signal is "GOOD", "weak", or "unusable".

I also like the way the tuning knob doesn't mute the audio while you're turning it. It gives more of an "analog tuner" feel to the radio. I just wish the knob had stronger detents (a more "notchy" feel). You need a very steady hand to accurately tune it while driving along a bumpy road!

 

[WPPCProductions]

Hi All, I have a plain jane GM AM/FM radio in my 1987 Olds Ciera,Excellent FM reception especialy in tropo times Like WPUR 107.3 Atlantic City.AM is good, picks 650 WSM good here in Connecticut with alittle hash from 660 WFAN. for a factory radio to sound is good for what I need.The Line out mod I've installed made it posible to record airchecks on my minidisk recorder when I'm on the road.Right Right now I'm trying to debate to get a HD radio, But I'm not to keen on the tuner front end specs.

 

[kevtronics]

Hi All, I have a plain jane GM AM/FM radio in my 1987 Olds Ciera,

Your car would be the perfect candidate for the classic Delco UX-1 radio with 5-band EQ and AM Stereo:

http://ourworld.compuserve.com/homepages/kevtronics/ux-1.jpg

 

[Tom Wells]

Hi All, I have a plain jane GM AM/FM radio in my 1987 Olds Ciera,

Your car would be the perfect candidate for the classic Delco UX-1 radio with 5-band EQ and AM Stereo:

http://ourworld.compuserve.com/homepages/kevtronics/ux-1.jpg

Notice that this radio has DNR ( !!!! ) but auto DNR. DNR was the finest anti-hiss/noise analog noise gate ever made.
I LOVED every rental car back in the 80's-90's with it, and am still a great booster of this system.
I bought a 1982 Blaupunkt Richmond with DNR switchable, where it made my 45-mile reception of WFMT classical music as
quiet as CDs before they were available.

Radio Shack sold a "video sound processor" in '82-86-ish that offered variable DNR, variable stereo-crosstalk cancelling (or "stage" widening).
I still use this processor on a 100% duty cycle over 20-odd years , for all my audio and pt 15 AM.
DNR was/is? made by National Semiconductor. I have one "raw" chip somewhere here awaiting application.

GM-Delco couldn't add a knob, but did add a button for 5 years, then auto-DNR for 1 or 2 more.
The auto-dnr meant that a particular cut-ratio was set for best overall result.
The switchable version was a bit more hard on the cut, but still crisp. It was fantastic on AM dx long distance drives.

Its action on well-recorded cassettes was also such that the result exceeded ( applying flame-resistant clothing) even the results achieved by compact discs. Perfect silence, very little gate noise off the silence into even the quietest music, with the gate noise perfectly complementing ( replacing )
any existing overtones that were present in the original recording lost or previously obscured by steady-state noise.
Weak FM or low-level cassetes suffered a bit more gate-hash, but I still prefer this to digital garbling.
In the case of the variable as I use at home, It is possible to "sharpen up" so many sources it is impossible to relate the usefulness.
From reel to reel originals to the worst 78's the variable cut DNR is able focus the result on what's really meant to be heard.

 

[robgrayson]

I've mentioned this one elsewhere before, but earlier this year I bought a used 2004 Mustang, and the AM part of the radio really amazes me. Then you tune in a station, it will start narrowband, then assess the signal strength. If there is sufficient signal, it goes into a wider-band setting, which allows you to hear cybals, bells, pings and tings I've never heard on AM before. Unfortunately, there's not much in the way of music to hear locally, but I sometimes flip on the "music of your life" station, which hasn't been 5K lobotomized, just to hear what' s there.

 

[tomservo]

My guess is that "MP" has something to do with "MPX" (the FM Stereo system) and "ADJ" has something to do with the measured level of adjacent channel interference. My hunch is that "MP" is showing the amount of stereo blending (low number = full stereo, high number = blended all the way to mono), but it's been a while since I had a chance to use that VW radio.

There's a glitch, too: the test mode displays "STEREO" even on mono FM signals. Meanwhile on AM, that mode offers the radio's analysis of whether the signal is "GOOD", "weak", or "unusable".

Awesome--I bet that's what those abbreviations are for. I'll have to see how ADJ acts next time I tune an HD-FM station.

Mine's got the same "STEREO" glitch, except on AM it says "GOOD", "weak" and "useless". I can think of a few full power strong signals that should be labeled "useless".

As much as I like this OEM radio, if I could get my hands on one of those Delco UX-1 models, I'd love to swap.

 

[kevtronics]

Mine's got the same "STEREO" glitch, except on AM it says "GOOD", "weak" and "useless". I can think of a few full power strong signals that should be labeled "useless".

You're right... I was trying to remember whether it says "unusable" or "useless", and I guessed the wrong one.

As much as I like this OEM radio, if I could get my hands on one of those Delco UX-1 models, I'd love to swap.

Unfortunately it won't fit, unless you cut up the dashboard. GM/Delco and Chrysler radios are wider than standard DIN size.

 

[WPPCProductions]

Hi All, I have a plain jane GM AM/FM radio in my 1987 Olds Ciera,

Your car would be the perfect candidate for the classic Delco UX-1 radio with 5-band EQ and AM Stereo:

http://ourworld.compuserve.com/homepages/kevtronics/ux-1.jpg

Notice that this radio has DNR ( !!!! ) but auto DNR. DNR was the finest anti-hiss/noise analog noise gate ever made.
I LOVED every rental car back in the 80's-90's with it, and am still a great booster of this system.
I bought a 1982 Blaupunkt Richmond with DNR switchable, where it made my 45-mile reception of WFMT classical music as
quiet as CDs before they were available.

Radio Shack sold a "video sound processor" in '82-86-ish that offered variable DNR, variable stereo-crosstalk cancelling (or "stage" widening).
I still use this processor on a 100% duty cycle over 20-odd years , for all my audio and pt 15 AM.
DNR was/is? made by National Semiconductor. I have one "raw" chip somewhere here awaiting application.

GM-Delco couldn't add a knob, but did add a button for 5 years, then auto-DNR for 1 or 2 more.
The auto-dnr meant that a particular cut-ratio was set for best overall result.
The switchable version was a bit more hard on the cut, but still crisp. It was fantastic on AM dx long distance drives.

Its action on well-recorded cassettes was also such that the result exceeded ( applying flame-resistant clothing) even the results achieved by compact discs. Perfect silence, very little gate noise off the silence into even the quietest music, with the gate noise perfectly complementing ( replacing )
any existing overtones that were present in the original recording lost or previously obscured by steady-state noise.
Weak FM or low-level cassetes suffered a bit more gate-hash, but I still prefer this to digital garbling.
In the case of the variable as I use at home, It is possible to "sharpen up" so many sources it is impossible to relate the usefulness.
From reel to reel originals to the worst 78's the variable cut DNR is able focus the result on what's really meant to be heard.

Thanks Tom, I have to check it out.

 

[Tom Wells]

I forgot to add.. the variable cut DNR does a great job of smoothing the zizzlies off medium-low bitstreams.

 

[kevtronics]

I have a standalone DNR unit, Dynamic Noise Reduction System 911. It's just a little box with inputs and outputs, Active/Bypass and High/Low Enhancement switches, and a Sensitivity adjustment knob. A red LED Audio Bandwidth bargraph shows you the current level of noise reduction. It's a rare find, but I got mine on eBay years ago. On the back it says "Manufactured by Advanced Audio Systems International, Inc., 4040 Moorpark Avenue, San Jose, CA 95117".

CRL had a competing noise reduction system called "dynafex" (they always spelled it with a lowercase "d"). They integrated it into some of their broadcast processors, and also made it as a standalone unit, the DX-1 for mono or the DX-2 for stereo. These are fairly common on eBay.

 

[RadioFixerCLE]

Hi All, I have a plain jane GM AM/FM radio in my 1987 Olds Ciera,

Your car would be the perfect candidate for the classic Delco UX-1 radio with 5-band EQ and AM Stereo:

http://ourworld.compuserve.com/homepages/kevtronics/ux-1.jpg

Oh christ, that's a flashback!!! My cousin had one of those in a car he had in the early 1990s. It was a nice sounding unit on FM. Unfortunately, I never got to enjoy the AM stereo feature because there was a bad ground connection somewhere, so AM stations came in all scratchy sounding -- with plenty of sparkplug noise.

Too bad the car caught on fire. :-[

 

[mr_elbows]

"Too bad the car caught on fire"

sounds like the bad gound was located.......