MR80 display ranging

[kevzep]

Hi,
I've been following this thread as I'm ready to send my MR80 in for a restoration. I purchased from a gentleman that was using it in his 2nd system and he was selling it as he was downsizing. I have not used it.
I would guess that a full recap would be in order and replacing the Q205 transistor. Anything else that you would recommend...other than the standard protocol? It is a late model CK374*

What I would do with your MR80 is to actually get it out plug it in and start running it over a period of time and see what issues if any it has.
They are a very complicated unit and require a lot of bench time even for an alignment. The are tricky little beasts to work on.
If you have no frequency counter issues there is no need to replace that transistor. There have only been possibly 3 that I have heard about with this issue, it doesn't necessarily mean because Gregory's and mine have faulted that they are all going to do it.
The most important part is who is going to do the work!! It is very important the person is familiar with the MR80, and I would also put aside a large pile of $$ to get it 100%.

 

[clinic-audio]

CK374* is one of the last unit produced

 

[kevzep]

CK374* is one of the last unit produced

Hello Patrice, did you receive an email from me 1 or 2 days ago? I am hoping it didn't go to the "junk" folder!!

 

[Fast996]

I'm going to send it to Audio Classics

 

[kevzep]

I'm going to send it to Audio Classics

I'd just let them decide what needs doing. They will know exactly how to tackle the job.

 

[kevzep]

***********Just an update on this as time progresses.************

My MR80 is performing flawlessly!!
It's the most solid it's ever been since I have owned it.

Anyone who has one, I would recommend having it aligned by an expert, there are so many parameters to be adjusted on these units, there is always a little bit of performance to be gained by taking a little extra time to work through the alignment.
One thing I would do is assess all the 4 trimmers in the MPX section, all mine were bad, scratchy and intermittent.
I don't know whether it was just my one, or whether the trimmers Mc used were not particularly good, but it is worth checking out. Their condition will be revealed when you come to the MPX alignment.

In my one the 19khz Osc trimmer was particularly bad, causing it to drift off and lose FM Stereo.....

Being stuck at home with the current hard lockdown, the MR80 is getting a lot of use, and I have to say it really does take things to a new level, jaw dropping sound quality!!

 

[jbailey930]

***********Just an update on this as time progresses.************

My MR80 is performing flawlessly!!
It's the most solid it's ever been since I have owned it.

Anyone who has one, I would recommend having it aligned by an expert, there are so many parameters to be adjusted on these units, there is always a little bit of performance to be gained by taking a little extra time to work through the alignment.
One thing I would do is assess all the 4 trimmers in the MPX section, all mine were bad, scratchy and intermittent.
I don't know whether it was just my one, or whether the trimmers Mc used were not particularly good, but it is worth checking out. Their condition will be revealed when you come to the MPX alignment.

In my one the 19khz Osc trimmer was particularly bad, causing it to drift off and lose FM Stereo.....

Being stuck at home with the current hard lockdown, the MR80 is getting a lot of use, and I have to say it really does take things to a new level, jaw dropping sound quality!!

View attachment 2331919

Greg's transistors showed up today, so hope he can apply the fix to his MR80. He does have my 2255 on his bench in the way, but progress is very good.

On the auto topic in the thread, I understand your level of effort on the F car! I've had a 79 911 turbo/aka 930 for 21 years. Dropped the engine once to fix broken head stud and do some "while I am in there upgrades".....fun stuff to have a garage project as well as electronics.

 

[kevzep]

Greg's transistors showed up today, so hope he can apply the fix to his MR80. He does have my 2255 on his bench in the way, but progress is very good.

On the auto topic in the thread, I understand your level of effort on the F car! I've had a 79 911 turbo/aka 930 for 21 years. Dropped the engine once to fix broken head stud and do some "while I am in there upgrades".....fun stuff to have a garage project as well as electronics.

Nice one, I am eagerly awaiting the outcome for Greg's MR80. He will need to take note on the pinout of the KSC1674 as it is different to the motorola MPS-H-10 which is in there. Its pretty straight forward though.

Also have to be careful when putting the lid back on Section 3 as its easy to pinch some of the cables, but he'll see that.

Its not too bad to access and doesn't take too long to replace the transistor.

Yes indeed, the only way I can afford a Ferrari is to do all the work myself, which is something I enjoy. '79 930, nice!! Is it a 4 speed? I totally rate those cars, my friend had a nice 1982 911SC Targa I used to look after when he would go overseas, and I had some great driving experiences in that car.
Always wanted to have a blast in a 930!!

 

[Gregory]

Greg's transistors showed up today, so hope he can apply the fix to his MR80. He does have my 2255 on his bench in the way, but progress is very good. On the [automotive] topic.. I understand your level of effort on the F car! I've had a 79 911 turbo/aka 930 for 21 years. Dropped the engine once to fix broken head stud and do some "while I am in there upgrades".....fun stuff to have a garage project as well as electronics.

JB added the MR80 oscillator transistors to the Mouser 2255 cap order. They (the transistors) were only 28 cents each, so four of them were 1.12 dollar. Got a ride in his Porsche 911 a few years ago and it's slick. The color is silver or gray metallic IIRC and it turns some heads, but I wouldn't want to ride in, or drive it across America to California. However the Turbo would really help at High Altitude in the Rocky Mountains. The altitude at the west end of Eisenhower Tunnel on I-70 in Colorado is 11,175 ft ASL.

-Greg

 

[Gregory]

My MR80 is performing flawlessly!! It's the most solid it's ever been since I have owned it. Anyone who has one, I would recommend having it aligned by an expert, there are so many parameters to be adjusted on these units, there is always a little bit of performance to be gained by taking a little extra time to work through the alignment.
View attachment 2331919

Great photo! That is the finest McIntosh instrument I've ever owned. It's a work of art, not to mention engineering, and the performance in NW suburbs of Chicagoland was fantastic. There's a pot on the top panel where you can `calibrate´ the signal strength LED stack (12 units) to the strongest station in your area. I set it to 12 for a station atop a skyscraper in downtown Chicago. For extra sensitivity, you could CAL it to a less powerful station for better resolution while DX'ing. It's a log scale indicator. The variable MUTING is great, as are ALL the controls.

Just TOUCH or grab the tuning knob, and the circuit unlocks in order to tune. The FM filter really works with no adverse affects. I could go on describing ALL the controls. Used to listen to a station in Milwaukee with lots of local stations nearby. Look for that station in the Chicago FM Log sheet. It's in the lower frequencies (top of FM log sheet) and the antenna direction is close to North. The quality was good enough to listen for hours.

A few Tips: best to GROUND the MR80 to a copper water pipe for best result. GREEN solid strand used by electricians is a good choice. Also have a lightning block connected to a copper rod in the ground where the antenna cable enters the building, and get a high quality QD (quick disconnect) plug where the ANT cable connects to the tuner.. so it will stand up to many connects/disconnects and not damage the ANT jack. Unplug cable any time you're away or when a storm is coming.


-Greg

 

[kevzep]

JB added the MR80 oscillator transistors to the Mouser 2255 cap order. They (the transistors) were only 28 cents each, so four of them were 1.12 dollar. Got a ride in his Porsche 911 a few years ago and it's slick. The color is silver or gray metallic IIRC and it turns some heads, but I wouldn't want to ride in, or drive it across America to California. However the Turbo would really help at High Altitude in the Rocky Mountains. The altitude at the west end of Eisenhower Tunnel on I-70 in Colorado is 11,175 ft ASL.

-Greg

Thats a hoot, 28 cent part causing all this!!
Agreed on the long trip in the 930!! I guess when you look at it, they are a sports car rather than a Grand Tourer, same would go for my Ferrari, not really Grand Tourer either...
Turbo's excel in high altitude for sure....

 

[TSmith8605]

. . .
My car is the one in the middle.....
View attachment 2327326

Beautiful car! Looks like maybe a 348 next to a Testarossa? I have a sweet spot for that line of cars (mid-engine Dinos, 3X8, etc.) and for almost anything Pininfarina. Some day maybe. Mean time, I'll have to make do with my 2012 Cayman and 1988 Carrera Cabriolet.

 

[kevzep]

Beautiful car! Looks like maybe a 348 next to a Testarossa? I have a sweet spot for that line of cars (mid-engine Dinos, 3X8, etc.) and for almost anything Pininfarina. Some day maybe. Mean time, I'll have to make do with my 2012 Cayman and 1988 Carrera Cabriolet.

View attachment 2332565


View attachment 2332566

Yes mine is the 348GTB (from 1993 on they were GTB/GTS rather than TB and TS).
From left to right, 512M, 348GTB, Testarossa. I think you can also see my mates 308GTS QV in the bacground as well.
Nothing wrong with what you have there, best of both worlds!! Classic and New!!

 

[Gregory]

Found the FM station in Milwaukee

Described earlier as WLTQ 97.3 MHz, is now WRNW.

https://en.wikipedia.org/wiki/WRNW

"Light 97 – Light adult contemporary became the format in April 1985 as "Light 97" with the WLTQ call sign."


The transmission towers were 71.4 miles north of the 4408 FM Yagi located in Arlington Heights.



Station coords: 43.111726°, -87.929591°


Chicago FM Log

The station appears in the original Log sheet, the online HTML version from the 1990s, and later in the spreadsheet.





Click to go full size


The info above says the station was tuned with Super NARROW IF bandwidth, Stereo FILTER active, 2 signal strength LEDs lit, and the Yagi antenna pointed 360° (due north).

The (X) in log above means the station could NOT be tuned with the MR80 using the omni FM turnstile antenna.


Radiation pattern — now WRNW

https://radio-locator.com/info/WRNW-FM



"The "local", "distant" and "fringe" lines on the FM maps correspond to the predicted 2.0, 0.5, and 0.15 mV/m contours respectively (of the ground wave propagation signal)."

https://en.wikipedia.org/wiki/Surface_wave#Electromagnetic_waves


Compare the contours above with the distance map at top.

It confirms what McIntosh said back in the day, `the MR80 can tune distant stations impossible to receive with ordinary tuners.´


It was one of my favorite FM DX stations!


Humor

When AK'ers post about using a tabletop FM antenna with an MR80 (in the basement even), sometimes I put "don't make me slap you."


-Greg

 

[kevzep]

Amazing detail!! Fascinating data!!
I wonder what the power of the transmitters were/are? In New Zealand currently the most powerful transmitter a radio station can use is a pitiful 3,000watts. Back in the 80's and 90's the transmitters were all 20-50,000watts, so quite a big difference in power.
So when I say I can receive FM stereo from Auckland which is 40 miles away, this is actually on the grand scale of things, quite good.
No other tuners I have had here or over my bench have been able to do this. I have had quite a few it has to be said.
The MR78 can receive a few but not in stereo.

So the power of the transmitters also comes into play as well.

Found the FM station in Milwaukee

Described earlier as WLTQ 97.3 MHz, is now WRNW.

https://en.wikipedia.org/wiki/WRNW

"Light 97 — Light adult contemporary became the format in April 1985 as "Light 97" with the WLTQ call sign."


The transmission towers were 71.4 miles north of the 4408 FM Yagi located in Arlington Heights.

View attachment 2334074

Station coords: 43.111726°, -87.929591°


Chicago FM Log

The station appears in the original Log sheet, the online HTML version from the 1990s, and later in the spreadsheet.

View attachment 2334090

View attachment 2334075

Click to go full size
View attachment 2334078

The info above says the station was tuned with NOISE filter on, Super NARROW IF bandwidth switched in, TWO signal strength LEDs lit, and the antenna was pointed 360° (due north).

The (X) in log above means the station could NOT be tuned with the omni FM turnstile antenna, even with the MR80.


Radiation pattern — now WRNW

https://radio-locator.com/info/WRNW-FM

View attachment 2334079

"The "local", "distant" and "fringe" lines on the FM maps correspond to the predicted 2.0, 0.5, and 0.15 mV/m contours respectively (of the ground wave propagation signal)."

https://en.wikipedia.org/wiki/Surface_wave#Electromagnetic_waves


Compare the contours above with the distance map at top.

It confirms what McIntosh said back in the day, `the MR80 can tune distant stations impossible to receive with ordinary tuners.´


It was one of my favorite FM DX stations!


Humor

When AK'ers post about using a tabletop FM antenna with an MR80 (in the basement even), sometimes I put "don't make me slap you."


-Greg

 

[Gregory]

I wonder what the power of the transmitters were/are? In New Zealand currently the most powerful transmitter a radio station can use is a pitiful 3,000watts. Back in the 80's and 90's the transmitters were all 20-50,000watts, so quite a big difference in power. .. I can receive FM stereo from Auckland which is 40 miles away, this is actually on the grand scale of things, quite good. No other tuners I have had here or over my bench have been able to do this. I have had quite a few it has to be said.

The MR78 can receive a few but not in stereo. So the power of the transmitters also comes into play as well.

Yes, comm engineers use what's called a Link Budget to describe or design RF/microwave systems. The general expression is: Received power (dB) = transmitted power (dB) + gains (dB) − losses (dB) https://en.wikipedia.org/wiki/Link_budget

The biggest loss of course is Free Space attenuation. You can't change stations specs, but you can choose the location (distance) from the tower, your antenna gain, and your antenna cable loss. A more expensive tuner with advanced features (think Mc) will be able to `pull in´ more stations. Modafferi had the right idea and McIntosh had the technology.




You might have seen this image before, my first Channel Master FM antenna mounted on a 16' galvanized pipe (used in horizontal chain link fence sections) installed in the mid 70s. Aluminum brackets (red) held the mast in place under the soffits, and the rotator is drawn in. No alignment bearing was used with short upper mast.The house had seen better days.




Fast forward 15 years with TWO 4408 Stereo Probes and factory stacking harness, the ultimate and most practical FM antenna system ever made IMHO.

This will increase gain by narrowing the elevation pattern of the array, with the same azimuth pattern as a single element.



300 ohm parallel transmission line is drawn connected to the Terminal block above, because it's less expensive and has the lowest loss per foot.

Now you're talkin' low distortion FM with GREAT DX capability.


-Greg

 

[kevzep]

Yes, comm engineers use what's called a Link Budget to describe or design RF/microwave systems. The general expression is: Received power (dB) = transmitted power (dB) + gains (dB) − losses (dB) https://en.wikipedia.org/wiki/Link_budget

The biggest loss of course is Free Space attenuation. You can't change stations specs, but you can choose the location (distance) from the tower, your antenna gain, and your antenna cable loss. A more expensive tuner with advanced features (think Mc) will be able to `pull in´ more stations. Modafferi had the right idea and McIntosh had the technology.

View attachment 2334470


You might have seen this image before, my first Channel Master FM antenna mounted on a 16' galvanized pipe (used in horizontal chain link fence sections) installed in the mid 70s. Aluminum brackets (red) held the mast in place under the soffits, and the rotator is drawn in. No alignment bearing was used with short upper mast.The house had seen better days.

View attachment 2334471


Fast forward 15 years with TWO 4408 Stereo Probes and factory stacking harness, the ultimate and most practical FM antenna system ever made IMHO.

This will increase gain by narrowing the elevation pattern of the array, with the same azimuth pattern as a single element.

View attachment 2334477

300 ohm parallel transmission line is drawn connected to the Terminal block above, because it's less expensive and has the lowest loss per foot.

Now you're talkin' low distortion FM with GREAT DX capability.


-Greg

I'd love to have an antenna setup like that, it would really help me in the location I am.
But you just cannot buy that sort of thing here in New Zealand, its very rare to see antennas like this nowadays. I am talking about those antennas, the one I have is a modest 5 element which is okay, but I wanted something higher gain but they just aren't available in VHF.
I guess I could buy another antenna same as the one I already have to increase my gain? That might be an idea....

 

[jbailey930]

Hi all - I am bringing this thread back up as @cawgijoe and I are going through @Gregory gear to sell for his family’s expenses. Unfortunately, he was not able to get around to putting his MR80 on his bench. We will cautiously follow @kevzep recommendation to see if that solves the ranging. It is an immaculate piece as Greg kept all his gear spotless. He has original boxes, receipts, panlocs, wood case (never used)! And all purchase receipts, manuals and service notes.

 

[kevzep]

Hi all - I am bringing this thread back up as @cawgijoe and I are going through @Gregory gear to sell for his family’s expenses. Unfortunately, he was not able to get around to putting his MR80 on his bench. We will cautiously follow @kevzep recommendation to see if that solves the ranging. It is an immaculate piece as Greg kept all his gear spotless. He has original boxes, receipts, panlocs, wood case (never used)! And all purchase receipts, manuals and service notes.

Someone is going to get some wonderful McIntosh gear!!
Please feel free to drop me a message if you want some more detail on the process and so forth....
I might have messaged Greg a detailed explanation on the process, I can share this with you if you need it.

 

[jbailey930]

Someone is going to get some wonderful McIntosh gear!!
Please feel free to drop me a message if you want some more detail on the process and so forth....
I might have messaged Greg a detailed explanation on the process, I can share this with you if you need it.

I put @Gregory ’s MR80 into my basement shop system a couple of weeks ago. I have an antenna feed for my receiver down there to an attic antenna. There was some scrolling but I was able to lock in stations. SQ is very good. All functions worked as expected. After a few days of using it, the scrolling returned. I tried swapping the plug polarity and changing the fast/slow scan function. There is an audible click as the the LED scrolls.

Today I opened it up and unplugged the RCA. The scroll slowed up bit hear the presets but continued to run…..so I may have matched my skill set on this diagnosis. I will power down, wait a bit then reseat the IC’s to try again.