This is why today the engineer melted from excessive cute.
Meet Peridot, a dapper young boy up for adoption at the Haven Humane Society.
….. And then Logan got this boop action and that was it, they had to wheel me out of there in the tank of a shop vac.
You have no idea how dangerous it is to be a broadcast engineer, do you?
The DDS exciter in these things really likes to flip out and overmodulate, but look, it’s perfectly in mask….. For what it is…..
Another PTek. Another questionable combiner. This one doesn’t even make any damn sense. I’m scared to open up the top of the transmitter to find out why it’s wired the way it is. The resistors are sitting on top of that hand cut piece of random PTFE and will cause a fire if they ever dissipate any significant energy. This is inside an FM2500PS transmitter.
This is a two port Wilkinson combiner that combines together the output of the left two pallets and the right two pallets. Why it’s floating on the thick PTFE slab, I cannot understand— these resistors appear to have the terminal configuration in which one lead of the resistor is the heatsinking base, and the other is the solder tab which just passes right through otherwise. WHY IS THIS BOTH INSULATED FROM AND ELECTRICALLY CONNECTED TO THE HEATSINK??!! Basically, what WILL cause this combiner to blow chunks would be any imbalance between the left and right sides of the transmitter – a single module failure will roast the entire rig. Catastrophically. See video below.
The lower line from each side goes to the start of the harmonic filter network, where they are just unceremoniously smashed together. This is… about the caliber of a badly built CB amp.
Dare I open the top and look around or have I suffered enough torture already??
(edit: yes… sadly I did!!!)
Page spam cut— click to continue. If you dare. I warned you, and Alex Hartman always warns ME not to open these transmitters and look around. But I do anyway. Then my brain hurts. ARGH
Continue reading »
I always used to wonder why every time I worked in a radio site I’d find the transmission lines going through the entry panel just goobered in there with silicone sealant or spray foam and the unused pieces of the Microflect / Andrew / CommScope / insert today’s name of the conglomerate cable entry port system lying around unused
Now I understand why and my arms and hands and back and legs all hurt, hours later
Woop Woop the FUCK POINT has been reached, this is as good as I can get this one. You just can’t get these things together if the cable doesn’t wanna go through straight.
The Wheatstone 531HD broadcast audio processor has a really Y2K-futuristic look about it, all it’s missing is neon colors and weird shaped non-rectangular windows.
There are two versions of the utility – one is called the Guru interface, the other, uh, isn’t.
First, the non-Guru
The jewel dots are draggable to adjust, and the knob controls are…. those… drag to turn things that have invaded all sorts of audio software
What look like text input boxes aren’t, you have to use the virtual knob / slide fader thing. Weird.
The usual nice meters from the Vorsis platform are available but they pop out as a separate window.
So what about the Guru interface?
Best I can tell, it does the same stuff but in a more convenient use of screen real estate.
Interestingly, there is a skin selector dialog. Only one skin is present and there is no real indication on how to modify it. Is this— a good thing or a bad thing? Who knows. Does this processor whip the llama’s ass? Maybe. Gotta play with it a bit more to be sure. It’s interesting how the 31-band limiter interacts with the program content though!
Putting this note out there for anyone who needs it—
The Wheatstone R-60, A-50, and other Wheatstone / AudioArts products use Amphenol MR series (Miniature Rectangular) for audio connections. The usual configuration of this connector is a 12 pin array – 4 rows of 3 pins.
Pinout for the audio inputs on each channel usually go like this: (Audio – = low, + = high… different strokes for different folks)
Ground / Audio - / Audio +
1 2 3 Input A Left
4 5 6 Input A Right
7 8 9 Input B Left
10 11 12 Input B Right
what the ass
The connector parts are all available from Digi-Key.
Connector Female Pins
Pin Extractor Tool
The original crimping tool Wheatstone would send along with the console was the Panduit (now Greenlee Communications) PA1645, which Digi-Key doesn’t stock. It’s available elsewhere. What I’ve been using at the office is an Iwiss IWS-1424A which supports five different sizes – size E works on the wire to pin crimp and size D on the strain relief tabs around the insulation.
GOTCHA: You may find an older Audioarts or Wheatie console prior to the mid 90s or so (I’m unsure on this date!) where a different style pin extractor is present – it’ll look like a fat hat pin with a spherical head. If you find this, DO NOT LOSE IT! At some point the Amp MR series connector was subtly redesigned, and the two extractor tools are not exactly identical. The newer MR pin tool is larger in inside diameter. The old tool is LOOOONG out of availability anywhere (I haven’t even been able to track down a part number on what it was!). The new tool will not cleanly release the old pins – you will wind up with one of the retention barbs on the side folded in half when it comes out. It won’t damage the connector shell when it’s ejected, though.
New pins will release in the old tool, but the retention barbs will be smashed way in there and be difficult to “reset” back into a usable position.
Chances are this won’t matter anyway, as you’re probably not removing the pins unless you’re entirely changing the cable that they’re crimped onto. 🙂
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.
Or not! I don’t think much is getting through this bad boy. This is a surge protector supplied by Nautel for installation with their transmitters. It’s glorious.