250 Watt 1GHz resistor

First you built a GPS jammer. Now, you're building a satellite uplink jammer. Are you working on a career as an RF terrorist?

Hint: The typical 2.4GHz barbeque grill dish antenna doesn't have a maximum tx power rating, mostly because the expected TX power levels are so low that it wouldn't be an issue. Judging by a quick look at the PCB balun construction near the feed dipole, I would guess(tm) about 10 watts maximum. The usual limiting factor is when the 0.5dB (11%) typical balun loss is sufficient to melt the balun or burn the PCB. For 10 watts and up, think about a better feed or maybe a waveguide horn.

Happy jamming...

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Even if everything radiated from the open opposite end, that would only be 0.25 mW, well below the maximum power levels allowed on the license free 2.4 GHz band.

And the VSWR is ?

It would not trip any SWR protection circuit.

So you are building equipment for the planned geostationary amateur radio transponder.

Your power seems to be a bit overkill, I have seen figures about 80 W with a modified satellite TV dish. This is a linear transponder so you should have the ability to drop the power level, so that it does not capture the whole transponder.

At 2.4 GHz at least bad quality RG-58 will have an attenuation about 1 dB/m, so a 100 m reel would attenuate 100 dB.

On a sunny day (Tue, 30 Sep 2014 09:13:55 +0300) it happened snipped-for-privacy@downunder.com wrote in :

OK, :-) Anyways I decided to mount my resistor on some old AMD Athlon cooler I think I have somewhere, and maybe it can go in the 9 inch rack where some other stuff like the PA will go. I will not run the full 250 W on it, so that could work, as long as the plastic from the fan is not melting.

On a sunny day (Mon, 29 Sep 2014 13:07:38 -0700) it happened Jeff Liebermann wrote in :

Well, it seems I do have a license that is also recognized by the US BTW for the 2400 to 2450 MHz band to 200 Watts.

I did select a dish that can handle that power.

Oh come of it. Do you actually have a ham license yourself? If not whats that repeater doing in your place?

You should read the whole thread, and not just bust in here with your all-knowing google links.

On a sunny day (Tue, 30 Sep 2014 09:26:27 +0300) it happened snipped-for-privacy@downunder.com wrote in :

Right. well I will use a processor cooler to cool the 250 W resistor. Its cheaper and smaller than coax, also coax would heat up and its impedance would change considerably I'd think.

Since you live in the middle of Europe, why do you want to waste that good transmitter power into a dummy load ?

With that kind of transmitter power and antenna gain, you should be able to make daily contacts to Berlin and Paris on a more or less daily principle using troposcatter propagation.

On a sunny day (Tue, 30 Sep 2014 13:29:55 +0300) it happened snipped-for-privacy@downunder.com wrote in :

I need the dummy for testing :-) That is to prevent sending some crappy signal to the stars...

There was moon bounce on 2 meter. I dunno if they ever bounced on 13 cm. IIRC the minimum moon bounce power used was a few milli watt, using the radio telescope in Dwingelo Netherlands.

3 mW! So that should be enough ,at very low bandwidth. But DVB-S is several MHz wide, and needs more power [1].

I have no data on the exact sensitivity and S/N of the receiver on the Quatar satellite, also the beam is wider, and expect some interference in that band.

14 dB C/N is a good value, I record HDTV via sat with 14 dB, although I have often wondered if the indication is correct, so many changes in the receivers and Linux API...

Maybe one day I will try some tropo scatter, lots of other projects... Maybe in the testing phase before 2016... The amp is in the mail...

I am not sure but I think I found a new way to test 10 GHz ATV links last night....

[1] I think you can make it as slow as you like, the Raspberry Pi DVB-S generator can now set the symbol rate on the command line. Not even the fractional divider induced jitter seems to destroy the signal... So you have slow scan too.

Yep. I'm sure all the Wi-Fi users will be thrilled by your high powered experiments. It's a point of contention here in the US. I managed to convince a few people at the ARRL that it would not be a good idea to mention that high power on 2.4GHz was legal for hams, but not for Wi-Fi users, before the FCC. The problem is that there are millions of Wi-Fi users versus about 700,000 hams, or which a tiny percentage operate on 2.4GHz. Were the FCC forced to make a decision, it would likely be against ham radio and high power.

I went back through the thread and didn't see any mention of the dish beyond the 24dBi gain, which happens to be the gain of the common barbeque grill style dish. Anyway, it's not the dish that limits the power. It's the balun.

Sorry. I'm not into diplomacy this week. Maybe next week.

AE6KS. It's been in my .signature since the dark ages of Usenet.

Occupying too much space. I guess you mean the MSF5000. I have two: I tried to give it away and nobody local wanted it. The problem is that most of the local repeaters are empty and devoid of users. I would put it, and several others that I own, on the air if there were users. Want both? Just pay for the crates and shipping, which I think will be more than what they're worth.

I did. What did I miss?

There are 300 messages in sci.electronics.design every day. I don't think anyone reads all of them. I read about 30, mostly due to lack of time. As for the "all-knowing Google link", I like to substantiate my claims with references and background information. I would gladly not post links, except I don't trust my memory to get everything correct, and I don't expect all the readers to understand everything I'm ranting about. A few links for corroboration and background are always helpful. If you fail to appreciate my efforts on your behalf, you're not required to click on the links.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

On a sunny day (Wed, 01 Oct 2014 00:01:10 -0700) it happened Jeff Liebermann wrote in :

Well actually its 2400 to 2450 at 120 W sat only, that is allowed here. The thread mentioned my trying it in the boonies, but alas it got lost in the noise. WiFis are mostly local, in a home and the occasional hotspot, so with relative a lot of signal, and should not really be affected that much if at all.

Well, now 75 W is not really that much.

Neither am I.

Yea, well, I think the average age of hams here is way up, OTOH I noticed some younger ones getting interested. The coming of the cellphone sure took away some.. But there is a lot of space for research, I am very much into 'do everyting [only] once', doing an uplink to a geosat seems fun, already made a nice 702 frame long station ID with a lot of motion and effects last night (720x576 mpeg2), still need to think of a better sound track than a single 1 kHz tone.. composed some music many years ago, hope I can find it, could have been on that harddisk I dropped way back then... As to 'stuff' I have no place to put it all, already threw away some old computah projects. The fun was in doing it, that was good, things change all the time, move on.

That some cellphone provider has bought the part of the 10 GHz band that is used for the downlink of the Qatar sat. Its secundary OK.

Yea, OK, I do the same thing... So my apologies.

There is plenty of spectrum. But governments have found they can make lots of money by auctioning a few kHz, so that makes us in a way an endangered species.

I'm not suggesting that you give up and do nothing. What's missing is what you plan to do with the 75/150 watts of RF, where you plan to point the antenna, exactly what frequencies you plan to use, whether you've coordinated your operation with other locals hams, and most important, whether you've bothered to listen on the frequencies with a receiver or spectrum analyzer. Your assumption that the common indoor home wi-fi user is the only users on the band is probably wrong. We have plenty of point to point links, often using exotic modulation schemes, here in the US. Most use highly directional antenna so you don't hear them unless you're directly in the path. There's also ham satellite and ISS ATV operation on 2.4GHz, which you're unlikely to hear unless you point your antenna in the right direction. Of course, you will have some TX output filtering to keep harmonics down to legal levels.

Do the math. 75 watts is about 49 dBm. Your 24 dBi antenna will increase that to 73 dBm or about 20,000 watts EIRP. Compare that to the typical 17 dBm or 50 milliwatt access point with a unity gain rubber duck antenna.

Of course, it's unlikely that you'll point your antenna into populated areas just to see if what havoc you can create. You're more likely to point it in some random direction, and let the antenna side lobes do the damage. Looking at the idealized data sheet patterns, they're down about -20 dB, so you'll only be doing 1/100th the damage.

I did a very rough estimate average of the approximately 150 members of the local radio club. About 60 as I recall.

Here, they join at any age between 12 and 16. They tend to be very enthusiastic and learn quickly. Mostly, they're boys. At some age, they discover girls, cars, or both, and they're gone. Oddly, they often return to ham radio when they're much older.

Yep. Ham radio used to be magic. You could talk to anyone in the world without wires. Today, the world has shrunk to where anyone can do the same with Skype. The magic is gone.

Sigh. All I ask is that you check the local band plan, make an effort to keep your signal directed, clean up any garbage that you might produce, and listen before you transmit.

I don't quite operate in the same manner but am occasionally guilty of emulating your methods. I just received two RTL2832U USB dongles (NooElec) and will probably waste enormous amounts of time playing with them, and producing nothing of value for my efforts. I bought two as I'm sure I'll destroy one during the experience (Learn By Destroying tm).

In the microwave bands, ham radio is usually 2nd or 3rd priority. For example, 420-450 MHz repeater operating power is severely restricted in the California central valley area due to military Pave Paws radar interference. Every year, some enterprising dot com devices a product that could only be profitable if they could obtain free spectrum from hams. Otherwise, if they paid the prices that the cellular and satellite operators were paying, the company would lose money.

Yep. We lost part of the 1.2 GHz band to GPS. We lost part of 220 MHz to worthless ACSSB for United Parcel Service. On the other hand, we picked up the WARC HF bands. It's difficult to tell what the future will hold, but I suspect that if you give ham radio a bad name by precipitating an interference problem, you might hasten eventually hasten the loss of the frequencies on the basis that ham radio is part of the problem.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

On a sunny day (Wed, 01 Oct 2014 08:46:39 -0700) it happened Jeff Liebermann wrote in :

I already showed the math, did you not read it?

You were complaining about baluns, that is what I replied to.

I mentioned that too.

Its not all that bad, and fried birds can be tasty.

We have a great working coversity network. where the transmitters are in sync via GPS, I can reach the whole NW and NE side of the country with my porto.

look a the map. There is even an android ap that can show which repeater I am on / is active at the time. Of course it is cheating, as data goes via cable, but it sure unites a lot of hams, it is a busy channel.

What is a problem here is internet over mains wires, if I hold my RF detector next to the mains it goes wild. You could buy those little ethernet plug in boxes, not sure who has those in the neighborhood. There goes your short wave.

Yes 50 MHz, 70 MHz, have not tried that (yet).

Was evaluating some uplink designs today, here is one: All frequencies in MHz

Qatar geostationay satellite

Linear transponder

2400.050-2400.300 MHz Uplink 10489.550-10489.800 MHz Downlink

Wideband digital transponder

2401.5-2409.5 MHz Uplink 10491.0-10499.0 MHz Downlink

Universal LNB: Rx IF LO

10700 - 11700 950 - 1950 9750 11700 - 12750 1100 - 2150 10600

Wideband: VCO

2401.5 - 964 = 1437.5 2409.5 - 964 = 1445.5

Narrow band: VCO

2400.05 - 964 = 1436.05 2400.300 - 964 = 1436.3

From this a Sirenza 1400-1560 VCO will do for the second mixer. 964 + 9750 = 10714 DVB-S tuner test out 964 1441.5 - 964 = 477.5 < filtered out 3 x 8 V 20 A in series | 1441.5 + 964 = 2405.5 24 V 17 A power I --- 964 only | | U2790B -------------------- X ------------------------ 2401.5 ----- bandpass --- 1 W driver amp ---- 75W Spectrian Linear RF Amplifier Board -( dish Q --- SSB RMS42-H 473.5 2400-2410 | quadrature ring diode | modulator mixer UBP1505 | | :256 Sirenza VCO | prescaler VCO Sirenza 9.3752 - 9.41211 951 - 977 VCO | set to 964 1400 - 1500 | set to about phase comparator --- loop filter ---> VCO2 405.5 - 964 = 1441.5 | |9.3752 - 9.41211 FPGA ------------------ < frequency control - user | 10 MHz Rubidium reference

Hope U use a real newsreader... guggle will likely fold it :-)

Maybe or maybe not, I also ordered some ceramic SAW 400MHz filters, 7.8 MHz wide on ebay, those SAWs cost next to nothing. This method above needs no steep filters, the U2790 only produces 1 sideband, no carriers, look up the chip. The 473 is easily filtered out in the 2.4 GHz filter. For this I have - or have ordered most parts, and there is still space on the board, I had the U2790 on board and removed it, it will be back.

This is one of 3 topologies I came up with, and the first one I will test.

Around the Bay Area, I've seen two other sources, PG&E Utilities spread spectrum communications and somewhere in the South Bay [downtown San Jose] you have some kind of 'drying' [sterilizing?] machine that really puts out some energy, also 'spread spectrum' looking.

Here's an old and incomplete list of non wi-fi users of 2.4GHz that I threw together many years ago. Add 2.4 GHz model airplane control to the list:

The "drying" microwave source is probably a food or fruit dryer or sterilizer. They run lots of power (up to 100KW), but are usually fairly well shielded[1]. One that I tracked down near the Watsonville CA airport was properly shielded but was also good at wiping out wi-fi use over about a 1/2 mile radius. It was quickly fixed by removing a screwdriver from a door interlock.

[1] For example:

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Also add the Mariott Hotel(s) to the list of interference sources:

FCC fines Marriott $600,000 for jamming hotel Wi-Fi FCC Press Release: FCC Consent Order:

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

On a sunny day (Fri, 03 Oct 2014 16:50:38 -0700) it happened Jeff Liebermann wrote in :

In German, English translation furtehr down page. EU want to raise the allowed maximum limit for PLC radiation by 20,000 times, sign petition:

In the USA, it's called BPL (Broadband over Power Line). We have various providers making futile attempts to make this faulty technology work, and generally failing. Their engineers find that transmitting into a power line antenna radiates nicely and claim surprise when they exceed FCC Part 15 radiation limits. The topology model for using power lines is seriously flawed as it doesn't scale. There's no way to provide the necessary data bandwidth to a profitable percentage of their potential customer base, when everyone is on the same big "party line" trunk with only about 20 MHz of available RF bandwidth.

In order to fix BPL, the only thing they can easily change is the radiation limits. They're not going to get the utility companies to isolate and balance the power lines. They're not going to get the FCC to allow additional bandwidth. So, they ask for more power, which isn't going to fix cost, topology, and radiation problems.

Hopefully, the EU will refuse to approve the power increase.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

This math?

That's the path attenuation, which doesn't have anything to do with cooking or melting baluns. That I was ranting about this time is that putting a 75 watt transmitter, into an undersized antenna with serious sidelobes, in a metropolitan location, is going to create interference for other users of the frequencies. Much depends on how much effort you put into preventing interference. Simply claiming that it won't happen and there's nobody nearby to complain is insufficient.

As for the balun, most baluns exhibit about 0.5dB loss. The typical barbeque grill dish antenna has a balun between the dipole elements and the nearby N connector. It's made for receive, so there's no problem with an additional 0.5dB loss in the balun. However, for transmit at 75 watts and a properly matched system, the balun will dissipate 11% of your power or about 8 watts. 8 watts through a very small PCB is going to burn the PCB. There's no easy way around the loss problem if you use a balun, which is why I suggested a waveguide, horn, cantenna, or patch feed, which eliminate the balun.

Very nicely done. We have various linked repeater systems. I don't see much use for them, so I don't participate. However, one local system that has my attention is a voter and simulcast system on

440MHz:

You might try some kind of low pass filter where the power enters the house. Maybe a big ferrite bead. It won't do anything for radiation from the power lines, but it will keep the RF from entering the house.

He have plenty of HomePlug devices in operation. In California, there are only a few BPL/PLC installations. Locally, the major sources of HF RF noise are: Solar inverter installations. Switching power supplies and chargers. LED lights. Computer noise. I have all the above in my house. When I want to operate HF, I have to turn off almost the entire house.

(...)

Forte Agent displayed it nicely, but wrapped it into an unreadable mess when I tried to quote it for a reply. I could put ">" symbols at the beginning of each line, but it's too much work right now.

Nice transmitter idea. I haven't worked out the filter requirements to prevent mixer spurs and unwanted harmonics from being transmitted. Designing a transmitter like that is actually fairly easy. Finding frequencies that don't create interference is difficult. You'll probably need some bandpass filters somewhere.

The problem with satcomm (I am NOT an expert on this) is not the transmitter. It's the receiver. The downlink is on X-band (10GHz) which will work with TVRO Ku band components but usually requires a wall of test equipment to get things right. This is typical:

Good luck.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

In Europe and especially Germany, the power line communication (PLC) system were created to break the telephone companies monopoly on telephone company local loop wiring.

Since those days, the telephone companies have been forced by EU to rent the local loop telephone wires to competing ISPs with at least something resembling realistic building and maintenance costs. For this reason PLC for internet providers is practically outdated in Europe. One has to remember that even wireless applications are making many ADSL systems obsolete.

Of course, PLC makes sense in home automation and for remote meter reading etc. but the power (and hence radiation) levels required are minuscule compared to ISP over PLC, especially since these services need to carry only a few kilo bits per second.

It should be noted that the power distribution system in Europe and the Americas are quite different. In Europe with medium voltage (MV) to 230/400 V service, each distribution transformer typically serve tens or hundreds customers, while in the Americas, the pig in the pole only serves a few customer.

In Europe, some remote meter reading applications can use the LV power lines to collect data and at the distribution transformer use e.g. GPRS over radio waves to forward the data. In the US, having distribution transformers at nearly every pole, you either have to use RF at every pig or use some PLC/PLC adapters at every transformer rated for medium voltages.

My opinion has been for at least ten years that any PLC/BPL communication is _not_ going to cause any real threat to RF spectral purity due to leaked radiation.