AM Stereo in the news

[DCFluX]

KYET runs the ever elusive Harris STX-1B AM stereo exciter.

http://www.facebook.com/photo.php?fbid=10151228594529573&set=a.10151155465494573.464176.677344572&type=3&theater

This one appears to be original to the station sometime between 1977 and 1981 as the plate lists the frequency of 1240 kHz. I am unsure if this was ordered as the V-CPM model (STX-1A) and converted or came as the 1B which is C-QUAM ready.

It was recently refurbished to repair a faulty B- power supply and unconverted for use with the Optimod 9100, which I never did find among the inherited equipment. That conversion turned the unit in to taking in L+R and L-R instead on the Left and Right inputs, which sure sounded humorous when feed with Left and Right.

That is the only thing in the air chain feeding a Harris DX-10.

 

[Jay Walker]

duplicate post.

 

[Jay Walker]

Ahem...yeah..you caught that, huh? The ground loop. Yeah there is a little ground hum in the signal. I haven't been able to get rid of it. It's in the line between the modulation monitor and the streaming PC. It's grounded good and that is about as quiet as I could get it. Could be in the sound card on the PC. I'm coming right out of the BNC connectors right on the back of the modulation monitor. Unbalanced L out, unbalance R out......

Michael

Hi Michael
In my experience with consumer sound cards, you might try using isolation transformers on the card input to break the ground loop. I had one machine in a limited use production room that had a low level hum that drove me batty. I tried all the tricks including lifting the "ground" on the A/C cord etc. Finally I tried those "cheap" Radio Shack encapsulated isolation transformers with the attached RCA and TRS cords. That did the trick. Your AM stream sounds real nice other than the low level ground loop.

Jay Walker

 

[HadYourPhil]

Actually I was going to suggest those little Radio Shack transformers! I've used them in similar situations and they do work well. Inexpensive, too!

 

[michaeljwyo]

I've heard a few people suggest those little Radio Shack transformers. These days I think I'd be better off ordering them online from Radio Shack since I bet even if we DID have a Radio Shack here (which we don't) I probably wouldn't be able to find them anyway. The little gray "ground adaptor" things is something else I thought about trying. I've used that trick in the past to battle the RF monster before. What boggles me is that we have so many other PC's here at the station (5) that have inputs and outputs to the consoles and mix balanced and unbalanced and I don't have any ground loops with those. However it DOES make sense when you say it may be on a different leg of the power. As a matter of fact, the TRANSMITTER and its equipment rack has its own power leg...that leg runs through the generator and is kept up by the generator in a power failure. It is ONLY the the transmitter, the 2 studios, and another equipment rack that are kept alive on generator power. The rest of the building is dead. Betcha 5 bucks that outlet that the PC is plugged into is NOT on the generator side of things and is on the other leg! I may even be able to just run an extension cord over to the transmitter's equipment rack where the exciter and processing are plugged in and that may solve the problem right there......or just try the "ground-lifter" trick. That might work too.
They may be old but I love these CRL's. I did have the opportunity to work with an Orban Optimod 9100b as well at another station I converted to stereo. They are not stereo anymore since they got purchased by another company and that company changed their frequency, spent the money for a nice BE-AM250a and saved a few bucks by leaving OUT the c-quam card. Cheap bastards. Just another cluster group that couldn't care less about stereo. They are still using the 9100b for processing but they are mono. The 9100 is pretty nice too but a little too squasy in my opinion. Then again, I didn't do a whole lot of adjusting....I may very well have been able to clean it up so it was clean and not so pushy. Most of that has to do with adjusting the attack time and release time. Anyways....writing another book here. Thanks guys and especially thanks to Matt Krick in Kingman for making another AM Stereo station happen!
If we all keep this up we may just stir up some more interest in C-quam...especially considering AM IBOC really just doesn't work.....c-quam DOES! But that's another discussion I'm sure

Michael n Wyo

 

[VelvetR]

Cheap and dirty but it'll get you at least temporarily out of a jam:

Remember the Weller and Wen soldering "pistols"? If you have one around and a couple of clip leads, jump the prongs of the AC plug across the humming audio circuit. The monster coil in those buns (you have to tape the trigger "on") loves 60-Cycle (see, I AM old) and hates audio frequencies. It was a prime trick back in the days of using phone lines for remotes and will also work with localized hum issues.

 

[chriscollins]

Those little transformers are amazing little devices. They have gotten me out of a lot of temporary jams with computers/sound cards/streaming. I keep 3 on hand.

Typically, I use them until we solve the true problem, then put them back on the shelf.

 

[satech]

Another station who cares -- 1430 WION in Ionia, Michigan:

Our station is C-Quam and sounds excellent, we'll run it as long as humanly possible and equipment available!

Take care,

Jim C.
Owner, WION Radio

 

[mgpt6]

If today's AM radios had circuits as good as in your Motorola Moduation Monitor . Audio is very good.

 

[kenglish]

We just gotta get McKay-Dymek going again.