Laptop power??

[Ships_Cat]

Yikes Lemain, you still making a last stand on this - sure your real name is not General Custer /forums/images/graemlins/crazy.gif. You have just about circumnavigated the original point several times now.

Irrational as the following reasoning is, I will just leave it that you are completely correct. You are the one who has blown up their computer due to rf and whose panel LED's (and who knows what else) light up with rf when you operate your radio. I will concede that despite the fact that none of my installations ever have such problems, I have only achieved that through luck.

Very strange what your hatred of cats can drive you to - don't lose sleep over it will you or, even worse, turn to drink /forums/images/graemlins/grin.gif?

John

 

[Anonymous]

[ QUOTE ]
I will concede that despite the fact that none of my installations ever have such problems, I have only achieved that through luck.

[/ QUOTE ]All transmitting antennae cause a radio field. That is what antennae do, it is the whole point of them! Near to the antenna, the field strength is very high and this is not a defect, it is normal. Indeed, most radio engineers carry a simple tester that is nothing more than an LED mounted in a Bic biro case, which lights up when near to a transmitting antenna. Pre-LEDs we used to use neons for the same purpose. If you don't understand this then yes, your lack of problems is probably luck.

Here in the UK you wouldn't even be able to obtain the foundation amateur licence with the dismal lack of knowledge you have. How do they issue amateur licences over there? Do you even have a ham licence, I wonder?

 

[Ships_Cat]

I can assure you that a LED will not light up all by itself in a rf field. The forward voltage drop of a LED (> 1v) across the PN junction is greater than an ordinary silicon diode, so for the sake of avoiding argumant let us just consider that it is the same as a typical silican diode eg approx 0.6v.

Now, you are going to need one hell of a field to develop a voltage greater than 0.6v on its little leads by sitting the diode all by itself in a field in order to forward bias the diode. For a LED the voltage required is at least twice as great, so it will not light either.

You will find that the field strength indicating devices you talk about have an antenna in them, all with active devices after that, as far as I am aware, in order to provide sufficient voltage necessary to drive the LED. They are not just a LED as you claim and their sensitivity is entirely dependant upon the length of the antenna connected to them and also the gain of the amplifier if an active antenna.

In fact some of the larger ones which you carry into the field to measure field strength use LED's to graph field strength ie only some of the LED's are expected to light - obviously if LED's lit up all by themselves in an rf field all the LED's in the bar graph would light up at once which would be rather silly - they don't light up because they have to be driven by more than the rf field in order to do so.

In any event, LED's light up on boat panels for reasons other than just direct pickup of rf on connected cabling during transmission so other knowledge is required to defeat the problem.

The only common thing around that I know of that will light all by itself when placed in a rf field is a fluorescent tube, but then the field has to be quite strong eg hard up against an antenna.

The worrying thing is that you have now told everyone that they should not use buck convertors (12v step up devices) to power a computer while using a transmitter on board (despite thousands of them being in use in that very application) and also told them that having their switchboard LED's light up is also normal. In fact, if the LED's are lighting that is at least an indication that other problems are likely to exist - a very common and potentially dangerous one is the autopilot losing control when the transmitter is keyed. It is easy to defeat these problems by sound engineering.

Perhaps you are trolling, but if not you are certainly time wasting. No doubt you will respond with another round of extracted quotes against which you reflect your "facts" but I think that most will see that you keep responding with things that sound great but are in fact very misleading technical half truths which they will see fit to dismiss as readily as I do.

So adios from this cat, I have better things to waste my time on than on you.

John

 

[Anonymous]

[ QUOTE ]
I can assure you that a LED will not light up all by itself in a rf field....
You will find that the field strength indicating devices you talk about have an antenna in them, all with active devices after that, as far as I am aware, in order to provide sufficient voltage necessary to drive the LED.

[/ QUOTE ]Why don't you try it? Take an LED, attach one leg to a piece of tinned copper wire the length of a Bic pen, hold the other leg and get near to a transmitting SSB antenna. It will light up - unless you live in a black hole - ha ha. Shouldn't take someone of your claimed experience and ability more than five minutes so why not do it before you post again on this matter, and report back? I presume that we can rely on your word even if we cannot rely on your technical knowledge?

Time you did some serious technical study before sharing your 'experience', methinks.

 

[Anonymous]

[ QUOTE ]
I can assure you that a LED will not light up all by itself in a rf field. The forward voltage drop of a LED (> 1v) across the PN junction is greater than an ordinary silicon diode, so for the sake of avoiding argumant let us just consider that it is the same as a typical silican diode eg approx 0.6v.

Now, you are going to need one hell of a field to develop a voltage greater than 0.6v on its little leads by sitting the diode all by itself in a field in order to forward bias the diode. For a LED the voltage required is at least twice as great, so it will not light either.

[/ QUOTE ]Have you never heard of field strength expressed in Volts per metre? Have you never heard of circuit magnification, Q? Even pieces of wire have inductance and capacitance and form a tuned circuit at rf. I discovered that you didn't understand basic electricity when we had a spat months ago and not surprisingly you don't understand radio either. What puzzles me is that you could licenced to be in charge of radio transmitters - at least those greater than a few Watts. But then maybe you are not licenced? The licence, you see, is only granted to those who have passed exams in the basic theory and practice.

 

[Ships_Cat]

I suggest that you read the post - I said ..You will find that the field strength indicating devices you talk about have an antenna in them and as you admit now yourself, the LED's have an antenna attached (a piece of wire) and even then be placed close to the antenna (they need active devices as well if not).

If you attached a piece of wire to yourself and laid that closely parallel to an antenna you would light up too, I am sure. But we do not commonly refer to you as being a bright light when it comes to rf fields now do we /forums/images/graemlins/smile.gif?

However, in the boat environment you will find that LED's light up for other reasons than just direct pickup on cables - in fact, more commonly so.

See what I mean by your half boiled responses. This could be endless, from my side it is like having fun arguing with a teenager who will not ever accept advice, listen to what is said, nor admit defeat /forums/images/graemlins/grin.gif.

So truly enough of this, I am getting embarrassed leading you into embarrassing yourself - besides it is probably against the forum rules /forums/images/graemlins/shocked.gif so I had better desist hadn't I. In any event I do apologise for doing so even though you are a known cat hater.

John

 

[Anonymous]

Since you must know that you don't understand the subject then I can only assume that you enjoy being irritating and are trying to be irritating. In which case you will be pleased to know that you are a success!

 

[Ships_Cat]

Oh dear, Lemain.

I can assure you that I do understand the subject (as I have explained before, I work professionally in the field) and people actually pay me very good money for doing so. Perhaps they are fools for doing so and such will undoubtedly be claimed to be so by you, but from their own successes in life and very high expectations I suspect that they are not.

How long can this thread go on for? Perhaps we could retitle it the Lemain Performing Cat Show /forums/images/graemlins/laugh.gif.

John

 

[Cobra25]

I had not had a serious computer crash for years and I can say that it was an unnerving experience, with the worry about loss of data, configuration, software, etc.

I take it you do not own a PC. Only Mac owners can make this statement. PCs are, well let's say less than adequate, which is why they, crash.

 

[BrendanS]

What a completely irrational statement. Mac's have exactly the same hard drives as PC's and they fail just as often. I use both, and my Mac's have had hard drive failure just as often as my pc's

 

[sailorgirl]

One other consideration is that not all 12v units are equal. Check their power consumption.

We've been using a mid priced Targus 12V block for a Dell laptop (which has recently replaced our ancient chart plotter)and it eats up the batteries. Now on the hunt for something with a lower ampage.

Sailorgirl