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Old 28 August 2010, 07:31   #11
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It won't work. Trust me, I've been a Ham for 25 years; the amplifier needs to be tuned for the frequency band in question.
My father used to be a keen ham radio user in the old days when it was the only way to talk to somebody overseas from here, and he had a 2kw (yes 2 kilowatt...) amplifier for his ham set but I remember 'tuning up' as an endless twiddling of knobs and whistling into the microphone while intently watching dials go up and down until he was happy. Usually took longer than the actual conversation ... so it's not a plug and play exercise but would burn a hole in the world when it was done right
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Old 30 August 2010, 12:30   #12
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From what i remember the maximum allowed for marine vhf is or was 25 watts,
Not sure about the UK, but in the US, anything over 25W on the water requires a bunch of licenses from the FCC. Operator, unit, and vessel and equipped with unit, I think.

If you need to talk to someone a ways away, well, yachties use Single Side Band sets, don't they? They reach a lot further than VHF (though they may require licensing as well, but the advantage of not needing exemptions from existing regs.)



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Old 31 August 2010, 00:38   #13
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. Only of use if you're talking to the CG (or another similarly equipped craft).

?
Please explain why that is
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Old 31 August 2010, 03:44   #14
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Please explain why that is
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Originally Posted by Starovich View Post
if you needed the extra power to contact someone (range?) then how they going to answer back if they don't have the extra power too?

and i'm no expert but wouldn't a taller aerial give more range due to the curvature of the earth and the whole line of sight issue?
'Cos the CG have "big ears and a loud voice" and Storovich's response applies to the others.

Nice to hear from you, BTW
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Old 31 August 2010, 06:13   #15
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questions
if you needed the extra power to contact someone (range?) then how they going to answer back if they don't have the extra power too?

and i'm no expert but wouldn't a taller aerial give more range due to the curvature of the earth and the whole line of sight issue?
Exactly! Hence the 25 watt working power for most sets. Rigging a 50 foot antenna on a rib may reduce the boats performance in other areas!

Linear amplifiers are great until everyone has one,so they are regulated for this reason. Best thing to do is get a good antena and have it fitted correctly and manage performance expectations accordingly. The coast guard have much higher antennas and I think clever repeater antenas for send and recieve.
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Old 31 August 2010, 07:22   #16
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SWR meter

I have a 27MHZ (CB) SWR meter and it does not work with the VHF (marine) I assume it is because there is too large a gap between the freq

TSM
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Old 31 August 2010, 13:09   #17
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Firstly.. you won't get an off the shelf "Burner" for 150MHz band I believe that 25 watts is the most power you can go to on that band of frequencies in most countries and anything else would be illegal to use. But a custom built one could increase the power.

Secondly.. Using more power won't be any more use to you other than to "bleed" over the top of other transmissions. It won't increase your range in normal conditions unless you're using two ruddy tall aerials. Then of course you could use directional aerials to get even further range without increased wattage.

Would there not be increased health risks in increasing the power significantly in a close range application too?

What are you going to be using this set-up on? Or is it just to see if it can be done?
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Old 01 September 2010, 18:12   #18
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What are you going to be using this set-up on? Or is it just to see if it can be done?
A bit of both and it would be to talk to a CG base station.

Part of the problem is not getting greater distance, it's getting around buildings in Central London that cause black spots. You appear to be able to receive in these black spots from CG stations, just not transmit.

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Old 01 September 2010, 19:33   #19
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I would guess that along the Thames that your mobile phone would be enough in an emergency. You could use the radio to co-ordinate the rescue when the emergency units are on the scene.

I am surprised that you have "black Spots" where you can hear the CG but can't raise them on the VHF. Perhaps you do have a poor aerial or connection that needs looking at? Should your radio setup be OK then perhaps you should map these areas and submit your finding to the CG so that they can improve their coverage.
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Old 01 September 2010, 19:49   #20
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I would guess that along the Thames that your mobile phone would be enough in an emergency. You could use the radio to co-ordinate the rescue when the emergency units are on the scene.

I am surprised that you have "black Spots" where you can hear the CG but can't raise them on the VHF. Perhaps you do have a poor aerial or connection that needs looking at? Should your radio setup be OK then perhaps you should map these areas and submit your finding to the CG so that they can improve their coverage.
In principle what you suggest is fine but in some places the mobile phones have bad reception areas as well as the radios. We do use a combination of VHF and mobile as it is but I thought a whopping great big powerful VHF might have solved the problem.....it sounds like a no though.

London CG and the PLA already know the black spots on the River if they decide to do something about them, well that's another question!
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