250 Watt 1GHz resistor

You can run resistors a lot hotter than you can run silicon devices. That translates into steeper thermal gradients and greater heat dissipation in the same space.

Some people wanted to make a diamond-based semi-conductor on the basis that they could be run hotter than silicon

or at least sucked in investors on that basis

suggests that the project hasn't got that far in the last ten years.

--
Bill Sloman, Sydney

On a sunny day (Sat, 27 Sep 2014 06:08:29 -0700 (PDT)) it happened Bill Sloman wrote in :

The famous Uncle Al poster in sci.physics (he is PhD chem) claimed some years agao he was only a pump away from making his own artificial diamonds... I challenged him, he left, tail between legs, not seen him since. Of course Beers see their market challenged, its all make believe, so much money for a piece of glass.

Not sure if we really need more processor power now, we could use more peace though, world seems to go 0bananas increasingly lately.

That little weapons factory called US is fighting an other enemy, created by them for sure.

But 4 sure there could be applications. Maybe a bit like whatsitcalled carbon nanonano tubes... Chips have been made with those, but mass production is hard.

I found that this resistor actually is good to 3 GHz, that makes it usable for 2.4 GHz, where I am working on a PA for the geostationary amateur satellite that is supposed to be launched in 2016 if the world has not evaporated or something by then, mind you launched by the Quatar Radio Society.

There is lots of fun stuff going on. Keeps your mind fit and hands busy.

So, where is your infinite heat sink when you need it? Did you loan it out? It's in the closet, maybe?

It's not made of silicon. It's something like nichrome on AlN or BeO. Let it get hot.

--

John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

Doesn't matter what material. 250W is a burner. You can switch it on with the 79A 310W FDP2532 MOSFET once. It got auto-off function. Work once.

Are you going to cook liquid nitrogen to get the heat out ?

I have used a 100 m reel of RG-58 as a dummy load for 1 GHz+ . It does not matter if the opposite end is open or shorted :-).

For higher power level, you had to unreel some few meters from the reel to help heat transfer.

genius!

so, let's see, most cabling is a bit leaky, down what? 85 to 100 dB, so you put in 54 dBm and transmit a healthy signal, right? ;)

Need a computer?

On a sunny day (Sat, 27 Sep 2014 12:35:16 -0500) it happened John S wrote in :

For reasonable values of infinite.

On a sunny day (Sun, 28 Sep 2014 18:10:42 +0300) it happened snipped-for-privacy@downunder.com wrote in :

Thats is about 59 dB attenuation ... It will still reflect.. 2 x 59 dB?

The idea is interesting though.

In a local stream/river perhaps? :)

Like, below the noise floor of your receiver.

Then terminate it ... with an 0603 resistor. Problem solved.

Cheers, James Arthur

Impedance tolerances on cheap cables and connectors make that the reflection is rarely better than -35dB or so. You need precision components to get a fair chance of doing better.

Jeroen Belleman

On a sunny day (Mon, 29 Sep 2014 05:18:10 -0700 (PDT)) it happened snipped-for-privacy@yahoo.com wrote in :

Genius!

Only prob I have is that 100 meter cable is bigger than my resistor + heatsink. To measure output power would it still be correct to measure the voltage over that cable at the lead end? And especially at lower powers...

I ordered one of these for sat uplink, this with a 24 dB dish I am eying makes about 7500 W

Testing will have to be somewhere in the boonies far away from me. Sidelobes..

Wonder if I can cook in the beam. Wonder if it can fry the sat receiver...

path attenuation = 32.45 + 20.log(2400000000) + 20.log(40000) = 312.095 dB

mm probably not... :-)

Whatdoyouthink?

On a sunny day (Mon, 29 Sep 2014 14:23:17 GMT) it happened Jan Panteltje wrote in :

Correction: its 32.45 + 20.log(MHz) + 20.log(km)

32.45 + 20.log(2400) + 20.log(40000) = 192.095 dB

So...

Easy--use a bigger heat sink.

All kidding aside, that is a pretty nice broadband resistor you bought.

Cheers, James Arthur

On a sunny day (Mon, 29 Sep 2014 08:28:27 -0700 (PDT)) it happened snipped-for-privacy@yahoo.com wrote in :

Yes, and it is 100% insulated from the mounting. Its this:

if you want one. If you wait long enough the Euro will be the same as the US dollar.

On a sunny day (Mon, 29 Sep 2014 14:38:32 GMT) it happened Jan Panteltje wrote in :

Working this out using the online satellite uplink budget calculator from

shows we have about 14 dB C/N: That is for a 3 MHz wide DVB-S signal, I will be transmitting testcard or test videos.

So it seems the setup is doable!

The downlink wil be at 10 +GHz and reception with a normal 80 cm dish. So 2 separate dishes.

Interesting!

: