PITAtek

Upon having the strange experience that a new supposedly frequency agile PTek would only work on half the band (seemed almost like an exciter unlock or something when I tried to dial in 107.1?) I decided to look at the exciter card to see if there’s a tunable tank coil or something

I wish I hadn’t now

SCA and composite inputs, J9 and J10 respectively. C66 lowpasses the composite sorta by shunting everything above an unknown frequency to ground. C65 highpasses the SCA, it’s in series. The two combine at fixed yet frequency dependent levels and go down that via near C63 and R33. U7 under the board is a voltage regulator. J1 is the RF out and L1 is the DC feed to the power amplifier just out of frame.

Yeah just go right ahead and stuff the audio inputs right on top of the RF out. No big deal.

Full view of the card. The DDS is at upper left.

Think you can get away from having your audio run across the butt of a voltage regulator by using the XLR jacks? No.

The trace going down the via next to R81 is one of the audio channels, and it runs right under the header connector for power and data to the board.

A word on this PA. This is a new LDMOS transistor from ST Micro. As such, its dissipation is really low, and it basically gets heatsinked by the leads and traces. Here’s the reference design…

What you get is significantly less copper. The big ground planes that’d soak heat away via the source leads are just not there… so a weird block thing was sandwiched under the board and I don’t even want to look at this any more

The stereo generator used to, in earlier designs, be based off a DSP that I’d heard they couldn’t get anymore. This stereo generator is what I could best describe as “deconstructed BA1414 feeding a high speed ADC”. I’m guessing the two PICs are used for timing generation and the 8 bit ADC, U8 / DAC0800LCM is probably used to generate a sine wave from a lookup table or something. conspicuously absent is any sort of audio filter to roll off program content above 15-18 khz, if this is present the generator flips the hell out. It’s a living nightmare on green circuit board. Gaaah.

Side note– the BA1414 I mentioned above is a chip made by Rohm which is used in a lot of really cheap little FM transmitter baubles and produces TERRIBLE output. It performs stereo multiplexing using a couple of poorly filtered square wave oscillators that are mixed with audio.

Go ahead, change the oil. I dare you.

This hilarious oversight found on an Allmand Maxi-Power 25 generator. The engine is a small turbodiesel utility engine made by Isuzu. The whole thing was assembled in Japan by Hokuetsu Industries….

… who hopefully sell a special bendy straw funnel.

Here’s the oil fill cap. The drain and filter are very easily accessible from the other side. But the filler… Oy!!

Above, the exhaust pipe.

Perhaps you can get in from the other side? …. Nope.

Look at that cute little tangerine sized turbocharger!

It seems to be like they could have added an access hatch above to make it easier, but yeah… Bring your Crazy Straws….

Target, what did you do??

Newly remodeled store, just… nauseatingly confusing layout. Maybe all the fresh carpet adhesive smell is what’s nauseating though. Oh yes, it’s CARPETED, which will guarantee it reeks of filthy carpet after a few months, like a CVS store does.

Central Illuminated Sadness Cavern (TM)

Slotting fees are nothing new in retail. A company must essentially pay rent to a chain store in many cases to get their product on the shelf, and must pay more for certain features such as end cap displays, shelving at eye level, not having the store’s own generic of the product displayed next to it— in this case certain brands of kitchen products paid to not be plunged into DARKNESS. My visual estimate says 2 f/stops down when you go back to the wall. Amazing.

And this isn’t even one of the layouts with the new “River” concept, which is a curvy path from the entrance that will parade shoppers past promoted items…

Funny how this layout in particular reminds me of the one that took Sears to its grave. 😉

Not quite as bad… Shasta Bally

As the Carr fire continued in Whiskeytown, we had no power to our site but a remote control continued operating on the generator. The final data I got from it showed 140F stack temp above the transmitter and 122F at its chassis.

The cause: burnination.

Thanks to Matt at Valley Industrial Communications for these pictures and for being a far braver soul than I…

Hey look, it’s still got a roof!

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Okay… I’ve calmed down. Now for silliness.

I’ve seen this on the Internet before but never thought I’d see a brake rotor this bad in person.

The (Oh, oh,) O’Reilly…. Auto Parts (Yow!) here in Willows just had a customer bring this in when buying new parts. Daaaaaaang!

Or should I say, YOW!

The O’Reilly Auto Parts jingle/radio advertisement music bed I’m referencing is a severe earworm. 😉

66 block stupidity

I need to find whoever decided to make both 66 blocks with the split down the middle and blocks without it with no identifying mark as to which type is which and pour glitter* over their head.

At left: no split. I’d been putting bridge clips on it for no reason and got a rude surprise (Zeppelin on a country station!) when I expected to have the left three pegs and the right three isolated.

At right: has the split. You have to install bridge clips to join the two sides.

* Biodegradable glitter of course – the sugar or seaweed based kind

Can it please be fall already?

It’s damn hot. One moment while I just pour this over myself.

Changing a tire in 112 degree heat sucks. Changing optimod cards and transmitters in an air conditioned building at 4000′ is preferable. All of them seem to be old age electrolytic capacitor failures.

Also, the Forester works better when the big hose stays on the spigot here.

See this cute little teacup? That’s the CVT fluid heat exchanger. Works fine on highways, urban streets, and literally everything but Shasta Bally…. I wonder if the cooler from an outback would fit?

This drives me to drink … coffee

The ultimate indicator of “am I on a crazy project” is, did I score another free coffee yet? Also did I ever mention how much I like Dutch Bros? Yeah so

Living nightmare of the moment:

Studio on air monitor consists of the following

Old Radio Shack BPC* bookshelf stereo amp with wires jammed in the speaker output terminals -> MYSTERY TWISTY SPLICE HELL CABLE -> unlabelled screw terminal strip -> ext monitor input on Wheatstone R60 console -> worn out control room monitor pot -> unlabelled screw terminal strip -> MYSTERY TWISTY SPLICE HELL CABLE -> PYLE** amplifier

The problem: the ancient Orban 8100A/XT2 processor started distorting heavily two days ago, likely due to Capacititis Electrolyticus. Nobody knows how old it is or if it’s ever been serviced. I swapped the station over to using an Omnia 6, which took until 3 am because of all the shitty spliced hell cable and then got the call at 6 am that the morning show hosts were hearing horrible echoes and were, instead of doing their show as usual, COMPLAINING ON THE AIR TO THREE COUNTIES ABOUT THE AUDIO PROBLEMS. Early on they asked if listeners could just call in and let them know how it sounded— nobody heard anything other than that the levels were a little low, as I hadn’t set the first stage wideband AGC to be as aggressive as it was on the 8100.

There was no audio problem on the air and they knew this.

Yet they made fools of themselves and made the station look like an unprofessional mess….

Kind of like this one. It took me 10 minutes of digging around and capturing wild Tangelas to find this. The twisted pair of doorbell wire runs off to a Telos ProFiler box. One wire of that goes to a speaker terminal, one to the amp chassis. How the hell did this ever “work”….??

As an added bonus the “loudness” button was stuck on at this amp so it had been basically… wrong…

We used to have an identical setup in one of our studios and I ripped it out because it was plagued by inexplicable leakage of audio from the station in the next room. I don’t know how it was getting in but the air monitor is now a reasonably good quality stereo tuner being converted to balanced by a Henry Engineering Matchbox. The amp driving the speakers in there is a Lepai “Class T” digital amp which has unbalanced inputs being driven by the other side of the Matchbox. It sounds perfectly nice and clean!!

So maybe my standards are too high but, you don’t go on air and trash your own station because you hear some echoes and distortion in your headphones. You leave a note for your engineer*** and the show goes on. That’s how this works, okay? Got it? Good. Now go entertain and inform the listeners, I’ll have the gear on order to give you the right audio to your headphones. Sheesh.

* Black Plastic Crap

** PYLE of shit

*** Please feel free to attach a Dutch Bros gift card (do they have those?)

Oh and here’s some electronic porn… The stereo generator in the 8100. 19khz crystal. That is all for now but I’ll be using these images in a later post

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