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Messages - KaySeeks

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I guess he was trying to get your attention

Achievement unlocked.

HF Mystery Signals / HAARP 6300 KHz 20 Dec 2017 0747 UTC ?
« on: February 07, 2018, 0910 UTC »
I am not exactly sure which SDR I was using at the time but based upon the similar modulation patterns that I have seen on YouTube videos, I'm assuming that this is probably HAARP. Does that seem right?

Huh? / Re: Happy Groundhog Day!
« on: February 02, 2018, 2207 UTC »
Hail the Groundhog, harbinger of Spring and filler of bellies! Hail!

I'm sorry but there is an insufficient amount of discussion around death in this thread.

Braised Groundhog Recipe

OK, may be this is moving in the right direction. Not human death but...

Equipment / Re: WOw, for those with $$ to burn
« on: February 01, 2018, 2148 UTC »
Note that this is LDMOS. Since we're talking big money, you might as well throw GaN into the mix (Hi Stretchyman!). The maximum die temperature is the same (225 C for both GaN and this LDMOS transistor) and it appears that the costs of both this transistor and GaN might be in the same ballpark too.

I got a chuckle over NXP making a reference design at 27 MHz for this. I assume it's a benchmark for 2-30 MHz performance, but I still got a kick out of a 1500 W amplifier reference design marked specifically for that frequency. "CQ SKIPLAND, CQ SKIPLAND", as they used to say back in the day.

Also, I am shocked that 500kw transmitters exist. Can you imagine paying for an extra 250 kw and get half an S point.

The Hungarians paid a lot of money for that 2 MegaWatt TX because they have a lot of expats living within 2000 km of Hungary who want to hear something from the homeland and sometimes their listening conditions aren't that great. The extra dB isn't for the folks living down the road from the TX, it's for the folks 2000 km away driving in their car, coping with MW band interference.

(I also wouldn't want to live within 30 km of that TX, but that's another story.)

Most receivers have bandwidth controls.  Run 5-10 KHz audio, and let the listener decide what they want to hear. 

+1 on that.

For a free radio station that could attract SHARKS, since any idiot can tune AM, but much better radios and SWL ops needed to tune SSB.

If you are going to be an SWL, you're going to be tuning in SSB at some point in your lifetime. It's sort of the low barrier to entry for the hobby. Everybody who is going to listen on SW to a pirate can basically handle tuning SSB to within 10-30 Hz. It's not terribly complicated.

Put some music into an SSB TX sometime and listen to it on a nearby AM RX. You will recognize that it is music regardless. Now imagine that signal getting into your neighbor's telephone or TV. They are also going to recognize it as music too. That won't help your case.

The authorities can tune SSB just like they can tune AM. They can DF SSB just as well as they can DF something with a carrier.

Your argument makes no sense.

The RF Workbench / Re: Amperage of Fuse in Streachy Lunch Box
« on: February 01, 2018, 0157 UTC »
A necessity for every bench, especially with the SMD stuff.

The best days of the 12AU7 were quite a while ago. Better get used to smaller stuff.

A five pack at Harbor Fright will set you back a whopping $4 https://www.harborfreight.com/5-piece-loupe-set-98722.html

Or get your self a cheap microscope that you can work under with a large working surface. I can't solder anything smaller than a 1206 (Imperial size) component without one. For this one, just rotate the base out of the way for bigger items.

Or go dee-luxe: https://www.google.com/shopping/product/4176465808603979983?biw=1610&bih=826&q=soldering+microscope&oq=soldering+microscope&prds=paur:ClkAsKraX0z1C-XT7GIxLaJw0QhdHj1niv3r6sUaq5qwvKXlDsDsoNpAtcegO4b96Jrxgvl0SV5FD9MobWqzHWmr7aB35gmBUxMF6cixIjpPKypp0kCY1-13zRIZAFPVH7135Rfy1l8ZSA-BVOYkot_eNvOGCA&sa=X&ved=0ahUKEwiRz5fQzYPZAhXs8YMKHXKjDOEQ8wII8wM

  0046 Z: AC/DC Have A Drink On Me.
  0050 Z: AC/DC with Have A Drink On Me (repeat).
  0054 Z: AC/DC with Have A Drink On Me (again).
  Continues till 0105 Z playing a loop of Have A Drink On Me.

They seemingly got too drunk to change the song.

Doesn't Al Weener need one of these?

Yeah, and on a relative scale it's "not that far away" from him. Customs duties would be rough though.

I once heard (therefore it must be true ::) ) That the IRF510's were  out of tolerance IRF511's from the same wafer.  Rather than throw them away, they just packaged them and reduced the specs a bit.

The downgrading process is certainly done extensively but I can't say for sure that it's done here.

Per this datasheet: http://www.qsl.net/n4xy/PDFs/Semiconductor_Data_Sheets/irf-510.pdf, it looks like if anything the 511 could be a downgrade of the 510 and not the other way around. Likewise the 512 and 513.

Contradicting what I wrote a few days ago, the 510, 511, 512 and 513 are clearly related. Not sure how much the 610, 620, 520 are related to this family.

Equipment / Re: The best undercover fm antenna on the market
« on: January 27, 2018, 2205 UTC »

Pretty sure that most commercial FM broadcast in the US is vertically polarized anyway so conforming to that makes sense if you want to attract listeners.

Not true.  Most commercial FM stations use right hand circular polarization and have done so since the late 70's. 

You come back at me armed with your facts and data! Darn you!  :D  All I can say is that my most recent knowledge on that subject came from a US retired broadcast guy who last worked in the 70s. That explains that.

By the way: https://en.wikipedia.org/wiki/Circular_polarization#FM_radio

"The term "circular polarization" is often used erroneously to describe mixed polarity signals[citation needed] used mostly in FM radio (87.5 to 108.0 MHz in the USA), where a vertical and a horizontal component are propagated simultaneously by a single or a combined array. This has the effect of producing greater penetration into buildings and difficult reception areas than a signal with just one plane of polarization. This would be an instance where the polarization would more appropriately be called random polarization because the polarization at a receiver, although constant, will vary depending on the direction from the transmitter and other factors in the transmitting antenna design."

This reads like a optical physicist nerd getting his nickers in a twist about terminology. By that measure, most radio signals are "randomly" polarized.

Note from the paper: They needed water cooling for the MOSFET.

To be fair, it appears that the use of the water-cooling system is only to achieve max power output and not because the transistor would be damaged with only a heat sink, as the authors mention.

You would not be able to operate this thing without some sort of heatsink because 20 W is far too much for a small package like that to dissipate safely. Reviewing the IRFP440 datasheet says that a reasonable heatsink attached with grease (presumably in still air) would result in ~30-40 degree C die temperature rise, which would not be anywhere close to the damage area the transistor but it would result in an increase in Rds and some other things that are important to power output and power handling. It would still work, but efficiency and power output would suffer. I'm not sure but I have a feeling that water-cooling would not be mandatory here. A reasonable heatsink and a fan to move the air over it might get it pretty close to to his published results.

I would put in some thermal shutdown circuit or VSWR protection or whatever for high(er) VSWR conditions if this were meant for radio and not a CVD plasma machine.

In any case, it was an undergrad thought experiment to see if it could be done. In the real world, I'd probably select a transistor that has a bit more thermal headroom. Technology has moved on a lot 1997 so many options.

Note from the paper: They needed water cooling for the MOSFET.

A minor detail!  :D

General Radio Discussion / Re: WWRB
« on: January 24, 2018, 2107 UTC »
I have no idea how they keep the lights on.

It's a hobby. An expensive one but that doesn't stop a lot of guys with their boats and whatever.

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