Sunday, February 26, 2023

The Journey - Part The Third

 Lest you think all is smooth sailing through The Straights of Pioneer, let me assure you it isn't.

In the case of this thing:

We ran smack into Halsey's Typhoon. It fought me Every Step Of The Way. Fix one thing, something else pops up. Fix that, and then you have to fix a brittle plastic part that broke while you were fixing the first item. Or a teeny, tiny part gets away from you, and goes sailing off into oblivion. The bent chassis was straightened so all mechanical assemblies were in proper alignment and dry-fit perfectly. The tape transport mechanism was taken apart and cleaned FOUR times. New drive belts, idler wheels, and pinch rollers were fitted. The last cleaning would have done a Class 1000 clean room proud. Use of lubricants was strongly discouraged, and highly controlled.

And STILL it doesn't work with front panel attached. It plays, records, and fast forwards 100% with the panel removed. Rewind is a bit flaky, so something is still amiss in the tape transport. It might be something subtle I'm missing, but I'm all out of speed, altitude, and ideas on this one. I went 10 rounds with this thing, and I'm battered, bruised, and bloodied. I'm "ahead on points", but I just don't have another round left in me, so I'm throwing in the towel, cutting my losses, and making a strategic withdrawal.

 

Nest stop in The Journey, The Bay of Nakamichi, where I hear the natives are friendly.

We should be pulling into port Monday afternoon.....


 


Tuesday, February 21, 2023

The Journey - Part The Second

 The next castaway we picked up in the Journey was the SX-980. Another crusty, dirty piece of derelict flotsam we thought "salvageable".

This was also another pleasant encounter, and after delousing our new arrival, we proceeded to give them a physical, and return them to health. It required a session Under the Knife to restore it to health, having been afflicted with a failing trimmer capacitor.

The offending part is the small teardrop shaped item dead center in the picture.

The offending part was replaced with a proper air variable device, more suited to this application.

A forensic anakysis of the failed part revealed a crack through the ceramic dielectric, seen here as  a dark line at the six O'clock position.

Now that I had solid frequency setting for the Local Oscillator, I could move on to aligning the FM Multiplex section . Some of the adjustments were a bit off, and two of them, the "19kHz Notch Filter", and the Left/Right Stereo Separation controls, were way off. The Multiplex alignment was rewarded with a perfectly locked receiver to the Pilot Signal, as shown here with the Lissajous Figure.

It's not "Text Book Perfect", as one of the Sine wave components being fed to it has a prominent 76kHz sawtooth component riding on it.

Finishing the alignment resulted in a perfectly tracking dial. It's nice to tune to 88.9, and your station pops in perfectly clear, with the tuning meter dead center. I deviated slightly from the procedure when I set the FM Muting and Signal Strength Meter to be more useful in the Real World.

And this thing has a really "hot" tuner. It easily exceeds the Pioneer specs by 6~10dB, pulls in distant stations far better than the SX-780 did, and I wonder how it'll do when I get the outside FM antenna properly mounted in the Spring.

Adjusting and testing the Power Amplifier was a breeze. The DC Offset and Bias controls adjusted smoothly, and wound up being about dead center in their adjustment range. To adjust the "Power Output" meters, I fed it a specified signal, measured the voltage across the dummy load, and set the meter adjust to read what the actual power is into an 8 Ohm load. One thing I accidentally "discovered", was although this amp is rated 80 Watts per channel, it easily made 135 Watts, with no sign of clipping, when I accidentally drove the input too high. So at it's rated 80 Watts, it has a LOT of "Headroom".

In fact, the SX-980 had such good test results and "Qual Ratings", that it was promoted to Senior Chief of Operations, responsible for all audio switching and reproduction duties.

In its Quarters:


And so, The Journey continues......





Saturday, February 18, 2023

And Now For Something Completely Different....

 Thought I'd take a break from recounting The Journey, and give a heads up on other projects.

Up first is a 1924 Chelsea Radio set. These were sold under different brand names, and this one is a "Transcontinental Type ZR-4". Almost sounds like a race car from back then, eh? It's from an era 60 years earlier than the FM Stereo gear I've been working on, and a radical departure from all the other radio gear I've worked on.

This was gifted to me by my next door neighbor, who had been trying to get it running for some years. He paid some moron an outrageous amount of money to "repair" it, and another jerk $200 to "refinish" the original wood case.

It's a basic "Three Tube" radio, using Type 01A tubes, a Low-Mu triode, and the most popular radio tube of the 1920's.

The first tube is a regenerative detector, followed by two audio stages. The two black items between the tubes are interstage coupling transformers.

Yep, broken wires in it, after the "repair". Has some bad solder connections, too, but I'll give 'em a pass because they're 100 years old...

The "refinished" cabinet photographs nice, but has 100 years of flaws, dents, and gouges showing. I guess the level of restoration/refinishing wasn't discussed when my neighbor turned this over to the two scoundrels.

Information is a bit sparse about this particular radio, but then I haven't researched into it very deeply. It's a classic circuit from the days when Radio was new, and fairly well documented. I'll also draw my own schematic of it "AS-IS", and replace some of the wiring. The rheostat for adjusting the filament voltage needs to be taken apart, cleaned, and correctly reassembled, as it looks like the previous "repair person" screwed it up. It's also missing a few bits I'll have to fabricate, and I'm not sure if my tube tester can do 4-pin tubes! The Bakelite knobs and front panel need a careful cleaning and relettering, and hopefully they're aren't any dead parts in it that I'll have to chase down. Should be a fun little side project.

And I'm still trying to figure out which is the "clean end" of this thing.

I knew it had taken a hit at some point in it's life, and suspected maybe the chassis was tweaked a bit. I took it apart (again), and started looking at things with a straight edge and a 90* square.

Yep, it was bent.


And not "just a tad tweaked", either.


I'll do an update on this showing how I got it all straight and square again. The front panel now just drops into place, and all the mounting holes line up. No binding any more on the transport mechanism that I can detect.

And still it doesn't work properly.

So I pulled the entire transport out, and will be going through it again, making sure everything is in alignment, and scrupulously clean of any lubricant that could cause slippage. And I finally understand how all the little mechanical bits, linkages, levers, solenoids and idlers work together and interact, causing a couple of light bulbs to illuminate in the old noggin.


I'll get it yet, but yowzur, what a trial........






Sunday, February 12, 2023

Pioneer SX-980 Back In Service, and Boy, What A Journey! Part the First

 


Some say the journey is more important than the destination. I knew the destination, mapped out The Journey, and then proceeded. 

This Journey wasn't extremely difficult, but took far longer than expected. I wound up going down several blind alleys, numerous Rabbit Holes, picked up and discarded various things along the way, and I didn't have the misfortune of meeting any Grues ("You're in a maze of twisty passages, all alike"), which was pleasant.

I know The World of Radio pretty well, and FM radio, too, but had never taken the path  into the Wonderful World of FM Muliplex Stereo before. I knew the principles, but had never applied them to anything. Required a whole lot of learning and thinking, and put me into Deep Ponder Mode more than a few times.

Along the Way of Discarded Items was an old Heathkit FM Multiplex Generator, and two Heathkit Audio Distortion Analyzers. While these had appeared suitable at first, they were a Blind Alley, and so they were left behind, and The Journey continued.

Realizing I needed far better equipment from my adventures along the Way of Discarded Items, my next stop was to get properly outfitted at the House of Messrs Hewlett and Packard, Purveyors of Fine Quality Instruments. Suitably equipped, I continued along my Journey to the Land of the SX-980, all the while continuing to seek enlightenment.

After setting up my Base Camp, now properly equipped, I proceeded to transit The Straights of Pioneer in search of the Destination.

The first encounter was with a certain SX-780, and pleasant indeed it was.

Dusty and crusty she was, matey...

But turned out quite nice after a good scrubbing.


She willingly joined our expedition, providing song and enjoyment in exchange for passage, and nothing more.

Off we set on the next leg of the Journey through The Straights of Pioneer, in search of the Next Level.

Part the Second will pick from there....





Friday, February 10, 2023

Been Busy, Pioneer SX-980 Finished, and Anniversary Dinner with SLW

 Got a full post cooking in the pot about the Pioneer, along with some other little projects.

Tonight's project was a lovely Anniversary dinner at the Sonny Lubick Steakhouse in Old Town with my SLW. It's actually Valentine's Day, but that's middle of the week this year, and the nice restaurants are packed.

Anyway....I'll leave you with this, a perfectly "locked" receiver, displaying a Lissajous Figure. The RF drive into the Front End of the radio was about 12dB BELOW the Pioneer spec for locking. This receiver has a very good tuner....



Wednesday, February 1, 2023

Final 747 Off The Line Does Some Fancy Flying

 Saw a post over at BRM's place, and found a link to this in one of the comments. It's the flight path from the Flight Aware website, and it's damn near as cool as Tex Johnson's Barrel Roll in the Dash-80.


Well done, guys!

Egad....'Tis a Trifle HOT This Week

 Or for what's remaining of the week. It was 97* today, and is expected to be 100+ through Sunday. The humidity is only 17%, so you step...