linear amplifiers.

Hi Samsgoneagain
I think you will find that you are limited to 100 watts unless you have a full amateur radio licence.
Regards Ronnie

A more efficient antenna would be a legal and better option.
For VKS737, the antenna can't be a fixed / permanent structure. Same regulations as set out in the outpost station license "License Conditions Determinations".
The mobile hf linears don't have any band filtering so spurious emissions are also amplified. You need to ensure that the exciter is clean.
The antenna would need to be rated greater than 600 watts, forget an auto-tune or standard tapped whip.
It is highly possible that such an amplifier would have peak input current near to 100 amps at 13.8 volts.

The amplifier would also have to pass the applicable type test standards

PeterD

Goodness, where to start?

Health issues: producing so much RF at the close proximity of a vehicle mounted antenna would be dangerous to you, passenger and other vehicles or pedestrians you were close to - we're talking brain tumours, eye cataracts and I don't know what else. Tony (who posts above) notes in another post today that transmitting 50W from a vehicle antenna (albeit at 144MHz) gives him a headache. Children would be _especially_ susceptible to damage. In fact I would keep children 25m+ away from the antenna when radiating the standard 100W.

Possible damage to the electronics in your's or the vehicles of others: the havoc which high power RF can wreck with modern electronic circuitry has to be seen to be believed - indeed Electromagnetic Pulse (EMP) is a technique used to permanently destroy hostile electronics (albeit with rather more than 600W :) Be a shame to have a nice VKS737 contact only to find your Engine Management Computer no longer works.

Power consumption: as Tony notes 100 amps plus.

Antenna: I doubt any commercial antenna for VKS737 could handle anything like 600W - you'll need to construct a purpose designed antenna.

It won't give anything like the communications benefit you imagine – you can work the world on 100W (and a lot less!) concentrate on your antenna installation. An Amateur friend of mine often works the UK on 1/10W (one tenth of one watt!) – mind you he does have a SERIOUS antenna :) I'm not a fan of vehicle mounted HF vertical antennas - consider a cut wire dipole in the trees or a squid pole - hard to use on the move though :)

It's, radio wise, antisocial (you'll splat harmonics all over the spectrum) and it's a breach of the Class Licence for VKS737.

My advice is; don't even consider it.

Mike Harding

PS. HF conditions are terrible at the moment (have been for a while) but they will improve – it's just a foible of HF.

No, for mobiles in the HF service they're not legal.
Their value is problematical.
Apart from the above hassles, increasing power at one end of the circuit will only allow your signal to be heard slightly better.
It will not allow you to hear anyone else better.