few-MHz empty frequency bands

ditto, but depending upon bandwidh, there are 'holes' in the spectral use. Edges between all those allocations.

Bingo. When asked to pay and you whip out rubles there will be sad faces. It was similar in former East Germany. They always wanted (western) Deutschmarks.

If you are a high-achiever the fruits of your labor will be skimmed off by the state, pretty much all of it, so you make the same as a regular worker (or sometimes less). Driving a cab can make more money than anything because there is the occasional guest with hard currency. So ...

Talking with them makes little sense. Most can't understand because they are indoctrinated, just like they can't really understand math or refuse to.

Seven more months :-(

You need to get out more. Some pHEMTs, e.g. the ATF38143 have 1/f corners about 10 MHz and flatband noise 6 dB lower than the BF862, not to mention 20x lower C_DG. I use them quite often.

Spehro & Co. do a lot of fairly wild stuff, like flying low temperature SQUIDs in airborne gravimeters for mineral exploration. So something physicsy is a good guess.

Cheers

Phil Hobbs

I hate to label but democrats just pushed through an FCC change to the internet with a 3:2 vote (?) that impacts us quite a bit. What's sad is that once the govt gets their fingers into something it usually enriches someone...., not me.

PS: the reason I hate to label liberal vs conservative, republicans vs democrats is because WE ALL LIVE HERE 111 I would much rather see arguments based upon, "How are we going to solve this?" Here's some proposals, what do YOU think? In other words a true dialogue to help all of us, instead of childish machinations to preserve archaic concepts [with images of children saying, nyah, nyah, nyah]. But as the old adage goes, "if it doesn't make money it wouldn't exist."

For good reason. The typical HF receiver has an overall NF (noise figure) of about 15-20 dB. One could easily build an HF receiver with a much better NF, but it would be wasted because the atmospheric noise is so high, that any weak signal that might be worth hearing, would be buried under the noise. Noise free gain is wasted because it will amplify both the signal and the noise equally, resulting in no benefit. What's really need in an HF front end is power handling capability, which sets the upper limit of the dynamic range. GaAs FET's are not the best for that.

Lots of car radios were slug tuned, too. That made pushbutton tuning easier.

I always thought it would be interesting (ie, difficult) to design a classic superhet. There's a multigang variable capacitor with curved plates and mica trimmers, all the oscillator and amp math, TRF stages maybe, IF frequency selection, stagger-tuned IF stages, antenna loading, all to be worked out without benefit of computers. An AM radio covered a 3:1 frequency range; an impressive math challenge.

The low Cin means you can get noise-free voltage gain from a transformer or a tuned circuit, which maybe explains the outrageously low noise temps that microwave gadgets have.

I've considered a compound amp, like a BF862 for the low freq part, and a transformer-coupled phemt for the hf stuff. Wish I had a use for it.

I've done the same, by parallelling them with a normal second-order LC diplexer in the emitter circuits so the pHEMT doesn't scribble its noise on the low-frequency range and the BF862 doesn't drag down the high frequency range with its high capacitance. I may have the opportunity to make some test boards for this fairly soon.

Cheers

Phil Hobbs

In that case the OP should look at the CCIR (now ITU-R) atmospheric (lightnings) noise curves for various days of the year and various hours of the day and various frequencies.

I really do not understand why someone might use a few Kelvin preamplifier at low HF, even if the antenna gain is something like -40 to -60 db (a ferrite bar antenna for MF/lowHF).

Looks like the step-up transformer, or paralleling phemts, is a wash on s/n for a given capacitive signal load. 4:1 stepup, or 16 fets, both give a 4:1 improvement. Is a tuned circuit any better? I suspect not.

Seems to me like an ideal distributed amplifier improves s/n without limit as you add stages.

Not every HF application involves antennas. The atmosphere is noisy, but lots of other interesting things aren't.

Cheers

Phil Hobbs

It's pretty tough to make a sub-picofarad transformer that works below a gigahertz, though. pHEMTs are a win as low as 30-100 MHz.

At high frequencies, C_DS combined with the rolloff of g_M with frequency produces a resistive component that adds noise and dissipates signal. (But you already knew that.)

Cheers

Phil Hobbs

It was 262.5 KHz, and it was done to make the IF narrower. That reduced the background noise, and rolled off the high end a little. Cheap car radios used the standard 455 KHz, and were crap in a car.

Piece by piece they are giving the old Missy Bells their monopolies back. In the end you then have the same as with government-run service, mediocre performance at very high cost. In the US we are already lagging far behind other coutries in average Internet speed and it begins to impact my income (and tax) generating activity. The Internet speedometer out here is stuck at 1.2Mbit/sec since almost 15 years. Progress? What progress? All this talk from Obama about his Internet push is just that ... the usual ... talk.

Wow, that's unacceptable (1/8 of the US average). It will also begin to negatively affect the price of real estate, like a house being too far from transportation.

While I would sign up for Google 1Gbps (no cap) at the current price (or double) in a heartbeat, I think I can live with a _reliable_

We're falling behind the countries with newer infrastructure. South Korea (Hellovision) is rolling out 1Gbps at $20/month, and other trading nations are not far behind:

Why buy a new 4K TV if you can't stream to it? (needs ~16Mbps per set just for that, uncompressed is >100Mbps).

Best regards, Spehro Pefhany

Not so much out here. People indulge in the more healthy acitivities of life. Horse, mountain biking, hiking, farming, ranching, all kinds of outdoors stuff. Flatlanders mostly can't hack it, they often leave after a few years.

That's big city speeds. Not sure how it's in the Canadian hinterlands but out here you are screwed if you live outside a metropolis. Sometimes you can get 5-10Mbit/sec from a cable TV company but only if you buy the whole bundle and then it costs in the serious three-digit per month. Plus they often slop the cable on top of the soil where it's only a matter of time until the first critter comes along who likes RG6 with mustard and fries.

Exactamente. Even services such as Netflix streaming don't make much sense out here. So people don't have that subscription and now we are talking hard revenue, taxes, jobs.