Transmitting in Glorious Independent Sideband AM Stereo from the Icy Shores of East Antaractica!

6945 KHz USB at 0300 UTC (8PM PDT)

Inovonics, Orban, Omnia, Texar, CRL, Wheatstone, DEVA... I'm trying to find a good deal on a processor but these are all so expensive, even used. I know theres software that exists but I would like to use something that doesn't involve a computer to keep everything analogue. This all started because I was looking for loudness meters, but even those are expensive and hard to find. It seems that the processors are mostly all in one compression, automatic gain control, loudness meter, etc.

Does anyone have any advice?

This information is geared towards experimenters that would like to use a vintage tube, amateur radio transmitter for broadcasting. The most suitable AM Transmitters will use Plate Modulation. Heising Modulation is a close second - the advantage is lower initial cost for a transmitter. This article is not intended for techs and engineers as it leaves out a lot of information that may interest this type.

Plate, Heising, and screen modulation are historical and modern AM techniques used in Amateur Radio transmitters. They differ by where the audio signal is injected: Plate Modulation alters total power at the anode, Heising uses a constant-current choke, and Screen Modulation controls gain at the low-power screen grid.

1. Plate Modulation (High-Level)

How it works: The audio signal is injected in series with the DC voltage supply of the final RF amplifier using a heavy, iron-core Modulation Transformer. The audio voltage alternately adds to and subtracts from the high-voltage DC, varying the plate voltage and output power.

Advantages: Produces pristine, high-fidelity 100% modulation with a highly linear envelope. It is the most efficient and rugged method for vacuum tube transmitters.

Drawbacks: Requires a large, heavy, and expensive modulation transformer capable of handling the full DC input power of the final amplifier.

2. Heising Modulation (Constant-Current)

How it works: A specialized sub-type of plate modulation. Instead of an audio transformer, a high-inductance Choke is placed between the power supply and both the modulator and RF final amplifier. The total current drawn from the power supply remains constant, with the current simply shifting back and forth between the modulator tube and the RF tube.

Advantages: Simpler and lighter since it eliminates the heavy modulation transformer.

Drawbacks: The plate voltage can never reach zero during negative audio swings, meaning it typically tops out around 80% to 90% modulation capability without causing distortion.

3. Screen Grid Modulation (Low-Level)

How it works: The audio signal is applied directly to the screen grid of a tetrode or pentode final amplifier, rather than the plate. The screen grid voltage controls the gain of the tube, altering the RF output as the audio fluctuates.

Advantages: Requires very little audio power. The modulator can be a tiny, inexpensive audio amplifier, completely eliminating the need for bulky iron transformers.

Drawbacks: Inherently non-linear ("S-shaped" curve). It requires careful tuning to avoid distortion and typically limits your maximum carrier output power.

It is illegal to use a transmitter on the HF Bands in the US, without an appropriate license, except under Part 15 of the FCC Regulations.

Clandestine Caster

They just started up at Midnight. I checked before and there wasn't anything.

We often use vintage amateur radio transmitters for AM in the shortwave bands. Unfortunately, there are more transmitters available that don't work well for this purpose, than those that do work well. Many vintage transmitters either don't have a Modulator built-in, or the Modulator used is what is known as "Screen Modulation". This is a poor form of AM Modulation that is weak and is not suitable for broadcasting.

We are interested in either Plate Modulation or Heising Plate Modulation. Both methods are suitable for AM Broadcasting. True Plate Modulation is available on transmitters like the Globe King. Unless we have very deep pockets, the Globe King id usually out of our price range. An affordable transmitter is the Globe Scout Deluxe with Heising Modulation. I own two, my last one was purchased for $70 USD.

Transmitters like the Heathkit DX-35, DX-40, DX-60A, Globe Scout 680, and the Globe HG-303 are not suitable for use as an AM Broadcast Transmitter.

Unless you purchase a vintage transmitter that has been restored, you will likely need to replace all of the electrolytic capacitors.

There are 10 slides in this article.

Vintage Underground Publication

Welcome to PirateRadioPlus. I think Mike u/KG7M had started a wonderful Subreddit that will attract a lot of interesting people. He's already seeded this Subreddit with great content.

So, let me introduce myself, I'm Stan. Mike asked me to participate as a Mod for this Subreddit. I'm very happy to do so not only to moderate but to contribute. I'm an EE and CS amongst other things. I'd like to do some interesting projects and share them with you. More on that in other posts to come.

That's me in the picture when I was 11. I can tell because I got my Heathkit GR-64 SW receiver when I was 10 and my hand is on the Q-Multiplier that I got the next year. You can see the QSL cards for I believe Radio Moscow and Radio Prague.

In 1968 the Soviets invaded Checkoslovakia and Radio Prague went pirate for 8 days. They evaded the Soviets by using mobile transmitters playing a game of cat and mouse that the Soviets had taught them thinking that should NATO invade the Czechoslovakians would be able to broadcast resistance. Kinda ironic how the tables turned.

So for 8 days this 14 year old and his GR-64 tuned into these brave privateers elude the Soviets. The next year I got my first after school job as a technician in a TV repair shop.

From June 1998 Electronics Now.

There are 10 slides in this article.

Just saying hello. I am a recently retired guy who spent 20 years in commercial radio and has had “personal” stations on both AM and FM for many years as a hobby. Part 15? Yes, on AM some but also have done much higher powered AM rigs. FM? Almost impossible to stay Part 15 if you want to cover more than your room so yes, I have played with much higher power there too. I do it all for fun, not intending to gain an audience, attract attention or create interference. Still, the thrill of hearing your own signal in the car is a special feeling. :)

BY RICHARD MARTIN

It wasn't a message from God, although listeners tuning their radios to 88.7 FM might have thought so. Suddenly the underground electronic music and jazz that had echoed from that spot on the dial gave way to Christian music and sermons. One night in late March, readings from the book of Ezekiel replaced the spacey lounge tunes of Esquivel.

It was the sound of K-Love. The 220-watt local affiliate of a Sacramento-based radio network offers "encouraging words [and] positive music," according to its mission statement. It bumped off the 10-watt Subterradio 88.7 ("Timbre," WW, Jan. 29, 1997), which had been broadcasting since June 1996 without a license and is currently the subject of an investigation by the Federal Communications Commission.

The local skirmish is part of a larger battle nationwide, in which pirate-radio operators, or "micro-broadcasters," are challenging the FCC's authority over the airwaves.

Subterradio's DJ Schmeejay, who insists on using a pseudonym, says he thought he was doing things fairly, if not exactly legally, when his station went on the air. But Schmeejay didn't know that the FCC had already licensed 88.7 to the Educational Media Foundation, a nonprofit Christian organization that runs K-Love and owns stations in Arizona, California and several Oregon cities. According to Binh Nguyen, a local FCC representative, EMF received a license in March 1996 for a station near Mount Hood.

K-Love didn't begin broadcasting on 88.7 until March, but a representative of EMF had already filed a complaint against Subterradio. In response, the FCC late last year traced the signal to the downtown area and started its investigation.

It was nothing personal, Nguyen says. "You have to comply with the rules," he says. "You couldn't drive a car without a driver's license. You can't operate a station without a license from the FCC."

Don't tell that to Stephen Dunifer of Free Radio Berkeley. In 1993, the FCC levied a $20,000 fine against the unlicensed Bay Area station, and Dunifer vowed to fight. As interest in his case led him into the pages of Newsweek and The New York Times, Dunifer inspired others to follow his lead and set up stations of their own, coining the rallying cry "Let a thousand transmitters bloom." In 1995, a federal district court judge denied the FCC's request for an injunction that would have knocked Free Radio Berkeley off the air. The case is still in litigation.

One of Dunifer's attorneys, Luke Hiken, says the driver's license comparison is unfair because telecommunications deregulation and bureaucratic red tape make it impossible for anyone but corporations to start a station.

"The FCC has created a licensing scheme for the super-rich," Hiken says from his Bay Area office.

As in many other locales, Portland's radio dial is increasingly under the control of a few major companies.

Last week, KINK-FM was bought by Boston-based American Radio Systems, which already owns the Portland stations KBBT 107.5 FM, KUFO 101 FM, KUPL 98.5 FM and KKJZ 106.7, as well as others in a dozen cities across the country. Meanwhile, government budget cuts have hurt public- and community-supported stations such as KOPB 91.5, KMHD 89.1 FM and KBOO 90.7 FM. Schmeejay and others view this turn of events as a corporate takeover of the airwaves, sanctioned by the FCC.

"Why should [the FCC] even have care of the airwaves?" Schmeejay asks. "I think the people should take that right away."

For a while, Subterradio did just that. Using filters to prevent its signal from bleeding into nearby spots on the dial, Schmeejay and his associates played an eclectic mix of electronic dance music, techno, ambient and jazz. Within months of going on the air, word spread of the station's cutting-edge playlist, and Subterradio could be heard blaring from stereos in downtown stores and coffeeshops such as Magpie and Umbra Penumbra. Schmeejay says he regularly received calls to the station's voice mail offering words of support, requests and donations.

Once the FCC received a complaint about Subterradio, however, that support was beside the point.

Three times, Nguyen visited a building at 333 SW Park Ave., where he suspected Subterradio was housed, only to be turned away by the property manager. Because Nguyen didn't have a warrant, he couldn't search the premises, and Subterradio stayed on the air until K-Love's more powerful signal drowned it out.

Schmeejay says he considered fighting for the spot, but has opted to pursue another place on the dial so he can spend his days behind the turntables rather than before a judge.

"If they need it to get the Lord's message out," Schmeejay says. "Then OK, we'll move."

Schmeejay and the FCC's Nguyen both advise listeners to stay tuned for further developments.

Our station was located in this building, in downtown Portland, Oregon. We had a Ground Plane antenna on top of the building and ran a FRB Transmitter and Amplifier. The FCC could not locate the station, even when they entered the building because we used an old "dumbwaiter" to access an area unreachable by any other means!

The following is from the Willamette Week Newspaper:

On Thursday July 3, 1997 — the eve of Independence Day, appropriately enough — La Luna hosts Secret Broadcast, a benefit for local underground station, Subterradio, and for an upcoming Secret Broadcast compilation. Five cutting-edge techno acts from around the nation — NYC's Soul Slinger and Jamal-ski, Miami's Supersoul, Wisconsin's OMCO (Outward Music Company) and local's Kuergii (featuring Dave Parks of Hungry Mob and Hitting Birth) — and three DJ's will contribute their talents to the free radio cause. The evening promises to be an exciting, mind-expanding multi-media event as well as a chance to show your support for a good cause. Oh, and you can dance your butt off, too.

The following is an interview of DJ Schmeejay — the man behind Subterradio — by Johannes Hoonroodts.

How did you get interested in radio?

Ever since I was a wee lad I've been searching the dial, trying to get to that 1% soul that somehow, amazingly, occasional slips through the system. I vowed at a young age that when I grew up and made a million dollars, I would buy a station, hire dj's with good taste and never play commercials. Well, I never really "grew up", I was kicked out of broadcasting school (for straying from the "format) and I never did make that million, but I still got my wish. In 1995 I was introduced to a technology called "micro-powered" radio or more commonly but inappropriately referred to as "pirate" radio.

What does pirate radio mean to you?

The term pirate radio applies more accurately to all those corporate stations to the right of 91.5: KNRK, Z-100, the Beat, etc. Pirates are infamous for rape, pillage and robbery on the seawaves. That's the same thing corporate robber barons are doing on the airwaves. Robbing us of all the freedom, diversity, and creative communicative possibilities we could be exploring via the electromagnetic spectrum. Supplying just enough filler music to keep people listening until the next commercial. It's sometimes difficult to distinguish where the commercials end and the music begins.

Was radio always this way?

No. For the first half of this century, the popular slogan was "the airwaves are for the people". In the sixties and seventies radio stations were fewer, smaller and generally independently owned. Competition was limited and stations played a wider variety of music. Then in 1978, the Federal Communications Commission passed a law banning stations with less than 100 watts of power, making it too expensive for anyone other than millionaire corporations and schools to operate a radio station. Last year, The Telecommunications Act lifted all restrictions on the number of stations one company can own in a given market. This deregulation means that the FCC will oversee the auction of the spectrum to corporate fraternities that don't have the people's best interest in mind.

So what's left for the active listener, the supposed owner of the airwaves?

Other than the few community based stations (KBOO, OPB), micro-powered radio may be the only refuge remaining for the people to reclaim their sacred airwaves. The technology is readily available at most electronic stores to set up your own neighborhood micro-station fairly inexpensively. Although the Federation for Corporate Control would argue that there are no frequencies available, there are still a few spots on the dial in most areas that can be utilized without interference to neighboring broadcasters, if the proper equipment is installed (for example, filters, compressors, etc.). A clean signal can make all the difference in the lifespan of a station, while helping dissolve the FCC myth that micro-broadcasting can only lead to chaos.

Is there an independent broadcasting movement?

Yes, The Association of Micro-Power Broadcasters is a worldwide movement for responsible micro's that is growing very rapidly. They provide legal advice, a periodical newsletter, and pass member info to many independent labels who support free radio by servicing stations with free records. There is no membership fee, but they do encourage tape swapping and request that members furnish a playlist every so often for their report. They just had their annual conference in L.A. last weekend.

Are there other micro-stations in the area?

The only other one that I know of here is in Vancouver, Washington, on 89.5 FM called Columbia River Radio. It's run by a very cool couple known as Rod Hardner and Bimbette. They play an interesting mix of roots blues, acid rock and country that you won't hear anywhere else on radio.

How does the government feel about free radio?

Oddly enough, the United States government is currently trying to force China to allow Radio Free Asia so that people will have an outlet there. Our government is supporting the station as a way to promote democracy in a totalitarian state. But when it comes down to protecting democracy here at home, it's another story.

Where can Subterradio's signal be heard?

The frequency we are presently using to broadcast is 91.1 FM. An average receiver should be able to pick us up in downtown Portland and anywhere close-in or high-up. On a good day even further. We have regular listeners as far north as Camas and Washougal, Washington and as far south as Tualatin.

What is your format? What is a person tuning in likely to hear?

Our "deprogramming" as we prefer to call it, is a fusion of sorts consisting of experimental electronica, jazz, hip-hop, ism, schism, poetic terrorists sound bites, anything interestingly inspirational that expands the barriers and parameters of sound. No need to label it, if we like it we'll play it. If someone doesn't share our tastes, there's always what's to the right.

Without sponsors, how do you keep this going financially?

It doesn't take a lot, but continually broadcasting 24-7 puts a lot of wear and tear on the equipment. Since we went on the air in May of '96, we have only had to go off the air, briefly four times. Technical difficulties and equipment failures attributed to three of those instances. To operate this right and consistently, we would have to raise a little over $100 a month. Asking for contributions over the air has managed to net a grand total of $45. I always found pledge drives annoying and I'd think there are a lot more creative and fun ways to raise funds, like organizing benefits. Unless you give people a good reason to donate, my experience has been that they don't bother.

​

The FCC Sinks Portland's Radio Pirates' Signal.

Willamette Week

By MARK BAUMGARTEN

For the past three and a half years, the Portland Radio Authority did something improbable. The illegal 100-watt station had managed to operate every day, broadcasting an eclectic array of music across the city, from Nob Hill to Mount Tabor.

Last Wednesday, that run ended with a knock on the door of the station's downtown studio. Inside, DJ El Fudge was finishing his two-hour set. Outside waited two men who identified themselves as agents of the Federal Communications Commission, demanding to be let inside.

"I told him to shut everything down and to not let them in unless they had a warrant," says 29-year-old PRA program manager Brian Riehle, who spoke to El Fudge via cell phone while the agents waited. "When the agents threatened to fine him $7,000 as an individual, he freaked out and let them in."

The agents photographed the equipment and walked out, leaving behind only a business card and the threat of a $10,000 fine. The visit from the FCC was unfortunate for the station and its roster of 75 local DJs. But it was hardly unexpected.

"I'm surprised we got away with it for as long as we did," says Gus Elg, Riehle's 26-year-old partner in PRA.

As a pirate radio station, PRA, which broadcast illegally at 96.7 and streamed legally over the Web at praradio.com, had kept a relatively high profile, hosting a number of concerts at local clubs. The Portland press took notice: All the city's major publications have written about PRA. Despite all this publicity, the station went off the air only once, for a week last year, when it learned the FCC was downtown hunting for the source of the station's signal. The government agency, they believed, had been tipped off by an Oregonian article written by Margie Boulé that offhandedly mentioned the station frequency. A week later, when the heat was off, they were back in business.

So when another Oregonian writer, freelancer Lee Williams, came calling to write about PRA last month, Riehle says he was willing to talk if the story focused on PRA's year-old Web radio station and would not mention the illegal FM broadcast. Despite the fact that the radio's illegal status is both a valid and more compelling news story, Williams agreed.

But when the story appeared in the O's Feb. 24 A&E section, it not only mentioned the FM signal but focused on the station's illegal activities, quoting Riehle as saying, "We've made it very easy for the FCC to say stop.... And when they do, we will." The article also included a paraphrased quote from Riehle stating that a broadcast license was "not expensive," making it appear that PRA simply chose not to obtain one. Riehle told WW that he was misquoted. Technically, licenses are cheap—if you can find one to buy, he says, adding that, in Portland, all frequencies are claimed.

Elg says that those quotes "read like we were waving the station in the FCC's face."

Williams agrees that a deal was struck with PRA, but says the terms had changed."Brian originally said, 'Don't put in the FM broadcast 96.7,'" Williams told Riff City. "That was one of the ground rules.... Later he asked me, 'What's your take on this gonna be?' and I said I was gonna mention 96.7, and he said go ahead."

It's impossible to say whose story is right, or whether that article tipped the FCC off, or even if the visit from the feds will be followed by stiff penalties. But one thing is certain.

"Everything is up in the air," says Elg. "But PRA is definitely off the air."

After a couple of weeks' break, PRA will continue as an online station.

Just wondering, where and how to listen.

A small but effective AM Transmitter from China. It's putting out around 3/4 of of a watt. Frequency is quite stable for a transmitter with an L/C Oscillator. It shipped from China and arrived broken. I had to remove, and replace the broken input gain control by modifying a standard part.

Range is about 2 blocks. Using an outside wire antenna, it covers my 5-story apartment building. An outboard amplifier can be added to boost the range. Of course it's not operating under Part 15, so it is not a legal device for users in the US.

Back in the 80's, shortwave pirates were pretty much exclusively on or near 7415 KHz. Now the focus is on 6920 to 6970 KHz. Why did it change?

• The AM Transmitter is available on AliExpress for about $25. In order to have a decent sounding station, you need a few extras. A Mixer is the most important part next to the transmitter. Inexpensive models are available, but don't go too cheap - the lowest cost ones have a lot of hiss. Mine works fine and cost a bit over $50 USD. Next, some kind of antenna tuner is needed for any range greater than 500 feet. If you are only interested in running a Part 15 station, a 10 foot piece of wire is all that is allowed for an antenna.
• Antenna Tuners can be built from a Variable Capacitor and a coil. For power levels under a watt, an old variable capacitor from a junked AM Tube Radio can be used. The coil can be wire, wound on an empty oatmeal box. Or you can buy a used ham radio antenna tuner. Make sure that it can tune down to 160 Meters.
• A Compressor/Limiter is a great asset. It adds punch to your audio and prevents over-driving the audio if adjusted properly. I use a Behringer Composer MDX 2100. I bought it used for $15 USD.
• A decent Microphone is needed to announce songs and interact with listeners. I use a Shure SM-58. I am a musician, and this is what I have for my vocals, so it's what I like - and use.
• Laptop and Desktop Computers are perfect for setting up your playlists. Almost any older computer can be repurposed to use at your station. I use Linux Mint as an Operating System. It's totally free. I use Pulse Audio to direct the audio from my laptop to the Mixer. I can select Bluetooth using "SQ-MIXER', or my laptop 3.5 mm in/out jack with a splitter. I also use Audacity for recording promos and music tracks. All of the mentioned software is free.
• An SWR/Power Meter is a needed item for adjusting transmitter output and making sure that your antenna is tuned, We are dealing with power levels under 1 watt so I am building an SWR Meter using a board from AliExpress, and a vintage meter found on eBay. I plan to install everything in an enclosure.
• I hope this information is useful. I started out wanting to broadcast when I was a kid and saw the Remco Transmitter Kit for children. I made a lot of mistakes along the way, but finally figured it out.

Running more than 100 milliwatts, and using an antenna greater than 10 feet is not legal in the USA. Proceed at your own risk if you are in the USA.

The background music is "Beyond the Northern Line" by Les Miserables, my aging band. If you find it annoying, just stop playing the video after the radio info is finished. I ran it through an AI Detector program for the AI haters in this community. I tend to overproduce as I provide promos for some stations. It probably would have scored better if I hadn't remixed it.

Photos of Bandaid Radio's studio and transmitter. They run off of the grid, the rechargeable batteries are shown at the far right in the first photo. Also in the first photo are an equalizer, compressor, mixer, modulation scope, transmitter, microphone, and station laptop computers.

Photo two shows a power supply, SWR/Power Meter, antenna switch, monitor receivers, and 2 kW amplifier at the far left.

Bandaid radio is owned and operated by Joh Black. It operates in the 43 Meter Shortwave Band on 6945 KHz USB.

My posts on Operating an AM Radio Station call for an Antenna Tuner. This is a very important piece of equipment for the AM station (not needed for FM). Because a resonant antenna at 1.6 MHz is very long, we must come up with a matching device when we use a shorter antenna. A quarter wavelength antenna would be 146 feet. Most of us will barely be able to find an area for a 50 foot wire antenna. So we use an Antenna Tuner to match our shortened antenna.

You will need 22 gauge solid, enameled copper wire. You can find scrap wire in old transformers and electric motors. You also need a 365 pf Variable Capacitor. Old, junk AM tube type radios all have this variable capacitor. The coil form is an empty Oatmeal Box. A couple coats of shellac should be applied to the bare oatmeal box.

Wind 75 turns of your wire, closely spaced,.on the oatmeal box. You will be "tapping" the coil. To do this you can twist a loop in the winding at the specific points shown in the diagram. The enamel coating will need to be scraped off of the wire to get solder to stick for the connections.

Follow the diagrams and you should be good to go. Remember, any antenna longer than 10 feet is not legal in the US. Neither is declaring war without Congressional approval, so I guess we are fine!

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