Hi power HF amplifiers

[A.Z.]

If you seek around you will find a number of very high power HF amplifiers, for example

https://www.emtron.com.au/products/dx3sp.php

now those amplifiers are FAR above whatever legal limit, so I'm really wondering WHO is their market target; for one, I understand that using such an amp at reduced power (at/below legal limit) will put the amplifier under low stress and allow the tubes to last longer, but then I'm not sure that's the reason why some people goes for them

So ... what's your take ?

[RoV]

If you seek around you will find a number of very high power HF amplifiers

You will also find a lot of cars capable of running far above any legal speed limit...
Probably the reason is similar 

[A.Z.]

If you seek around you will find a number of very high power HF amplifiers

You will also find a lot of cars capable of running far above any legal speed limit...
Probably the reason is similar 

Hm ... but then there aren't all those nice chicks to pick up on the air, and there aren't (at least not that I know) RF speed tracks

Come on, my question was serious

[TimFox]

Of course, with all those digital monitors built into the amplifier panel, the legal operator can keep the output within regulations...
Before I looked at the ad, I assumed the "nominal" market for the amplifier was for laboratory purposes, but the wording is obviously aimed at amateur operators.

[eb4fbz]

Not everyone sticks to legal limits, and 4kW is at the low side for some of them.

Just search for homebuilt amplifiers arround 3CX10000A7...

[NiHaoMike]

Perhaps there are special licenses that allow use of more than the usual power limit for certain purposes like bouncing a signal off the moon?

[TimFox]

It's been decades since I was interested in this question.
Do the American FCC and its foreign equivalents "type approve" equipment for sale for use on the amateur bands?

[CJay]

If you seek around you will find a number of very high power HF amplifiers, for example

https://www.emtron.com.au/products/dx3sp.php

now those amplifiers are FAR above whatever legal limit, so I'm really wondering WHO is their market target; for one, I understand that using such an amp at reduced power (at/below legal limit) will put the amplifier under low stress and allow the tubes to last longer, but then I'm not sure that's the reason why some people goes for them

So ... what's your take ?

I know you've got the Italian flag in your profile but...

Honestly?

Italians and Russians.

Rules and regulations seem to be pretty much optional for operators in both those countries.

I'm pretty sure other countries are similarly lax but they're the two that spring to mind.

[iMo]

The "ownership" and "operating" are two different things from legal point of view..
You may "own" a 10kW transmitter, but you are "not allowed to operate" it (ie. transmit into an antenna).
Also in most countries (ie in EU) the local authorities does not care about (does not monitor anymore) the HF bands, thus running ie. 4000 Watts would most probably get unnoticed by them.. 
PS: 4 times more output power adds "1S" only on your S-meter reading..

Example: If you transmitted from Paris to New York with 100W output power, and the NY OM gave you a "56" report, with your 6400W he would give you a "59".

[A.Z.]

The "ownership" and "operating" are two different things from legal point of view..
You may "own" a 10kW transmitter, but you are "not allowed to operate" it (ie. transmit into an antenna).
Also in most countries (ie in EU) the local authorities does not care about (does not monitor anymore) the HF bands, thus running ie. 4000 Watts would most probably be not noticed by them.. 
PS: 4x times more output power makes only 1S more on your S-meter reading..

First of all anyone (not just EU) could buy those (again, the link was just an example) or build an HF amp going above legal limit, then it isn't just an "italy and russia" thing; if those amplifiers are on the market AND the companies are still in business, I doubt they're just selling to EU people, hence my original question, focus on it, please

[iMo]

They run it full power.. How would you know they are above the legal limit??

[CJay]

The "ownership" and "operating" are two different things from legal point of view..
You may "own" a 10kW transmitter, but you are "not allowed to operate" it (ie. transmit into an antenna).
Also in most countries (ie in EU) the local authorities does not care about (does not monitor anymore) the HF bands, thus running ie. 4000 Watts would most probably be not noticed by them.. 
PS: 4x times more output power makes only 1S more on your S-meter reading..

First of all anyone (not just EU) could buy those (again, the link was just an example) or build an HF amp going above legal limit, then it isn't just an "italy and russia" thing; if those amplifiers are on the market AND the companies are still in business, I doubt they're just selling to EU people, hence my original question, focus on it, please

Buying such an amp as the Emtron isn't illegal anywhere that I know of, if people want to buy it then let them, it's up to their conscience how they use it but most of the people I know who have equipment capable of running much higher than legal limit don't boast about breaking the rules if tey do.

My experience of nearly 40 years of operating radio is that the stations I hear boasting about using illegal power levels are Italian or Russian and the 'freebanders' too. Then you have the Superbowl AM CB users but they tend to build their own or buy some overvolted, overdriven thing, not a properly designed amp like the Emtron.

Personally, I would rather someone were using a well designed and built piece of equipment like the Emtron, that way at least if they do break the rules it's going to cause less interference to legitimiate users.

You also need to consider that most if not all ham licenses specify power limits at the feedpoint, so while it's unlikely and a ridiculous waste of power, 4KW might not be hitting the antenna.

[coppercone2]

you can do overload testing of stuff with it

i.e. dummy load characterization for drift, testing power components, etc. A 10x underrating might be one way to make a reliable system.

[iMo]

Experienced ham radio operators may recognize such stations, but generally it is extremely difficult.
Based on a specific actual propagation conditions while doing many QSO's during a short time period in a specific heading first skip you may somehow distinguish when somebody reports much lower output power than actually is using. But that is an extremely rare situation.
This year I copied a QSO between an UK and a Norway station at 40m band where the latter added QRP in his call in order to attract the attention of the UK station.
They made the QSO and the UK operator added ".. and my dear OM do not tell me you are qrp, you are at least 1kW"..

But normally you cannot easily recognize whether a station runs 400W or 2000W or 4000W especially when doing dxes..

During an 1 minute long QSO the signal (shown by your S-meter) may fluctuate between S2 and S9 easily (so called QSB) because of the ionosphere fluctuations.
That is 9 - 2 = 7 "S" - that is like the transmitter would have changed its output power from 1W to 16kW and back during that QSO..

[coppercone2]

and that thing would make a hell of a plasma chamber amplifier if you give it a tuner

[A.Z.]

Thank you all, this is confirming to me the fact that ham hectics has been definitely buried many years ago, and it also makes me feel in peace with all the 6KD6, PL519 and 813 (skipping the Eimac based ones) I've built in years

[David Hess]

There are industrial, military, aerospace, and electromagnetic compliance test applications for that sort of equipment.

[coppercone2]

driving the water soaked hard line conductor with 1500W for an output power of 50W?

[A.Z.]

There are industrial, military, aerospace, and electromagnetic compliance test applications for that sort of equipment.

sure, but look at the description of that amplifier I used as an example "QRO", "Bands from 160 to 10 meters" and then more, I don't think they are targeting industrial/aerospace/... AND then, that power is far above legal ham limit

[A.Z.]

driving the water soaked hard line conductor with 1500W for an output power of 50W?

LOL !

Well, that's another way to waste money

But seriously, what's your take ?

[TimFox]

Another legitimate use for high-power RF linear amplifiers is MRI, but that usually needs 64 MHz--not a ham band.

[A.Z.]

just found a similar discussion here

https://forums.qrz.com/index.php?threads/illegal-high-power-hf-amplifiers.659044/

[coppercone2]

I think so long you have output monitoring on the actual signal then having the high power to get a transmission out despite a fault is a good thing, they are supposed to be emergency capable systems.

Not a issue for a small time ham but if someone is using it in some kind of capacity in a remote location, perhaps with snow, intense climate, etc. These possibilities will always be somewhat at odds with a neat bureaucratic solution.

I read that story before, that there was a ham club with bad heliax soaked with water that was using excessive power levels to transmit very modest signals because of losses. It sounded foolish (more like they did not do maintenance tests) but if this happened during some record snow storm or something, it could be useful. It's one of those things like when you get on the highway if the situation arises you might need to step on it for a little bit of time to avoid an accident, or say passing a semi truck, unblocking a emergency vehical that needs to respond on a narrow road, etc.. the excess speed that is not normally used has its justifiable uses.

[David Hess]

There are industrial, military, aerospace, and electromagnetic compliance test applications for that sort of equipment.

sure, but look at the description of that amplifier I used as an example "QRO", "Bands from 160 to 10 meters" and then more, I don't think they are targeting industrial/aerospace/... AND then, that power is far above legal ham limit

But the RF output power meter is calibrated to indicate a limit of 1500 watts.  All 1500 watt amplifiers should be able to put out some amount more than 1500 watts for adequate linearity at 1500 watts.  This one just appears overbuilt more than most, and should also get better operating life than most.

Reading various reviews of the Chinese FU-728F tube makes me think that the power claims are exaggerated.

[thinkfat]

Isn't the legal limit about power radiated by an imaginary isotropic antenna? What if your feedline is just oh so lossy?