Hi power HF amplifiers

[Bud]

I didn't realize people got credit for cable loss and got to make it up. If that is what you are proposing.
...
Also, how are directional antennas handled. .

In Canada at least we do not get credit for cable loss, the output is measured across a matched dummy load. And with this method, directionality of the antenna is irrelevant for the purpose of RF power legal limit.

[Bud]

Worked many QSOs with Americas, Europe and Russia on 20M with this mobile setup with an all-band 100W Icom and top loaded stick. The most interesting one was mobile-to-marine mobile with a guy on a cargo ship in the ocean somewhere near Florida, lol.

[M0HZH]

I don't necessarily agree. On HF, once you have a decent setup antenna gain is generally more expensive than power gain, especially below 20m. For example, if you have a wire dipole in a tree at a good height, you will need a tower & 3-el Yagi to gain almost 3dB, on 7MHz that is a US$3000-4000 job; increasing power from 100 to 600W (almost 8dB) costs half that.

And receive capability is not about antenna gain but about S/N ratio, so increasing antenna gain does not directly translate to better receive (it receives more signal but also more noise).

[David Hess]

And receive capability is not about antenna gain but about S/N ratio, so increasing antenna gain does not directly translate to better receive (it receives more signal but also more noise).

Directivity has a major influence on S/N, and improving directivity can be a major cost.

[A.Z.]

And receive capability is not about antenna gain but about S/N ratio, so increasing antenna gain does not directly translate to better receive (it receives more signal but also more noise).

Directivity has a major influence on S/N, and improving directivity can be a major cost.

well, I agree on diirectivity, but it isn't the only factor, as an example this antenna

http://www.kk5jy.net/LoG/

will give surprisingly good reception, but isn't so directive and is really cheap

[Theboel]

I disagree with You about directivity try to build one if You want to see what I mean.

back to over legal limit I think I can Understand if legal limit is 1500w some one use 2500w amplifier to overcome cable loss etc but for people who use 5kw or more with legal limit only 1500w I think that is wrong thing to do.

[coppercone2]

always keep in mind that some people have crazy transmission losses from say snow. Never would hurt to have extra power on hand for whatever reason in a critical situation, so long ERP is monitored.

[thinkfat]

I don't necessarily agree. On HF, once you have a decent setup antenna gain is generally more expensive than power gain, especially below 20m. For example, if you have a wire dipole in a tree at a good height, you will need a tower & 3-el Yagi to gain almost 3dB, on 7MHz that is a US$3000-4000 job; increasing power from 100 to 600W (almost 8dB) costs half that.

And receive capability is not about antenna gain but about S/N ratio, so increasing antenna gain does not directly translate to better receive (it receives more signal but also more noise).

Ever worked your way through a pile-up in CQWW? I've operated DL0TD for two or three years in CQWW SSB, I can attest to the value of antenna directivity

PS: do you know what a "crocodile" is?