few-MHz empty frequency bands

Dear Leader Radio, 7140 kHz!

Shades of Warren Zevon:

Cheers

Phil Hobbs

The commies used to plop their radio stations into ham bands. So we made it a sports to plop our SSB signals right onto one sideband of those and everyone fired up their kilowatt amps.

One of them was Radio Tirana, a propaganda transmitter of the Chinese back in the 70's. One of us mentioned his phone number and got several calls. There were actually people listening to this commie stuff. We couldn't believe it.

A few K? (at 50 ohms?) or something higher?

George H.

No it would not be thank you..

Jamie

Which is why they offer to sell you a reactor for those devices, one on the input and output.

Jamie

I used to listen to Radio Moscow from time to time, just to see what it was they wanted me to believe that day. Sometimes knowing what a liar wants you to believe is almost as useful as knowing the truth about what they're up to.

Back in the Cold War days, some of the most powerful transmitters in the world were the Soviet jammers, blotting out BBC and VOA and such.

When I was a kid I used to listen to Radio Moscow on my ancient Hallicrafters S38. It sounded awfully prissy to me; Communism didn't seem like much fun. I spent a month in Moscow in 1980; Communism

Once I wanted to blast one of those rogue commie stations again when they intruded into a ham band. But they played such nice symphony music that I just could not do that and instead listened. Many of those countries had (maybe still have) very good large orchestras and when they played ethnic music it was gorgeous.

Talking about prissy, the Soviets also tried to scare the world with their over-the-horizon radar. Toc-toc-toc it went, over large swaths of the shortwave band. Da big show. One day it stopped. After the USSR finally collapsed a group of ham radio operators visited the radar site in Krasnoyarsk. Turns out it probably stopped operating because the buildings began to fall apart.

That's because it does not work. Did you have to stand in one of those looong lines just to have the privilege to buy a small bag of oranges? Or a geyser of hot water shoots out of the street pavement, the temps in the upper floors drop towards freezing and absolutely nobody does anything about it?

So you enjoy listening to Obama speeches?

What weirded me out is that we Americans, the enemies of Communism, got premium VIP service in the USSR. We got escorted onto empty airplanes and served hot tea while the russians stood outside in the freezing rain. We could buy premium imports, and eat in fancy restaurants, that Muscovites weren't allowed in. That all seemed reversed to me.

Moscow had a municipal hot water system (I did some thermal measurements on that, among other things) that ran to hotels and apartment buildings mostly unmetered. Apartments were hot in winter, and to adjust the temp people just opened windows.

At one construction site, all the building materials were being stolen by the workers. They said "There's nothing wrong with taking this. Nobody owns it."

A very strange experience.

I hear that bbq rattlesnake is good. Tastes like alligator, I bet.

Most of those slitherey reptile-ish things are similar, like unagi or frog legs.

Car radios used to be something different, 240 KHz or some such. I never understood why.

It's a feechur of communism. You have hard cash, their people don't.

Makes sense. If it doesn't cost anything, it's wasted. Another feechur of communism; no ownership (of even self).

Talk to the "Occupy" people. You'll find the same attitude. Heck, you'll find the same attitude in half the Democrats.

Shouldn't be today. We're getting there.

Several things - check out TheBlaze.com - G Beck has more traffic than NYT or NBC.

He reported on a conference entitled "The White Privilege Conference" in Madison, Wisconsin in March of this year. Many (radical) educators converged to stay in hotels and discuss strategies to "educate" children about the dangers of white male privilege. It's the idea that white males got where they are because they had (racist) advantages over other racial or gender types. The idea is to incorporate these ideas into Common Core and other curricula. This will be done in a stealth way, though obviously the word is getting out what these miscreants are up to. This has nothing to do with racism, and everything to do with grabbing power and brain-washing children.

The originator of "white privilege" is a Professor McIntosh, who is a "gender studies" at some college.

I advise you, on hearing this, not to get wound up, but to just methodically do something about it. It's just a plan to teach racism to children.

(...)

I'm still trying to decode what you're doing. My only question is how much bandwidth do you need? That will determine the base line noise level and somewhat determine the lowest possible frequency that can be used.

If you're shopping for a quiet part of the HF spectrum, I suggest the various HF marine bands. Stay away from the coast station frequencies and concentrate on the vessel transmit frequencies. Unless your device is ocean going, you're unlikely to get clobbered by a nearby transmitter. However, the available "clean" bandwidth is limited, which is why I asked how much bandwidth do you need.

Also, consider that HF has quite a bit of atmospheric noise. If your amp is very low noise, and your wiring somehow decides to become an antenna, you might have problems with noise pickup. At low frequencies, ground loops make good antennas. Think balanced differential from end to end.

Otherwise, just tape to the wall one of the numerous mutations of the FCC frequency allocation chart, and throw darts at it for likely frequencies. Frequency table:

The atmospherics band noise at 3-5 MHz are at least 40-60 dB above thermal (300 K) noise. If you are interested in a few K noise temperatures, you should check for an abandoned mine perhaps 1 km below ground with only 300 K noise temperature.

While a good GaAs preamp might have a noise temperature below 100 K and with liquid nitrogen/helium cooling much lower than that, I have never heard of anyone using GaAs FETs at HF :-).

Assuming the OP is doing some medical/physical experiment, my suggestion is to go deep under ground and use a Faraday cage to keep the external noise down (300 K thermal noise).

If you just need to keep the HF out of a Faraday cage, no need for tight doors with lots of Fingerstock, just make a 1 m wide by 2 m tunnel perhaps 100 m long with well conducting metal walls and this will act as an waveguide, with a cut-off frequency well above the HF band.