Re: Power on digital modes


Adam Jacobs <jacobs.adam@...>
 

The problem with the "minimum power to accomplish the desired communication" thing is that folks will QRO pretty far before they give up and throttle back. If you're not begin heard on JT65 at 30w, odds are you won't be heard at 100w... but that doesn't stop folks from giving it a shot or 12. :)

Could you explain a bit more about how PSK's average power is 41% of the peak? If you have a link that would be great.

-73 Adam W7QI

On 4/30/2013 3:35 PM, Larry Mundinger wrote:
 

On 04/30/2013 05:31 PM, W. J. Karle wrote:
>
>
> It seems to me that users of digital modes gradually are increasing
> their radiated powers. Whereas we once prided ourselves saying that
> our rigs were running 30 watts or less, now I am seeing more and more
> hams saying that they are running 50 and 75 watts.

I have seen some of this as well. I wonder if there is a question on
the test about duty cycle? Digital modes are 100% duty cycle and
transceivers aren't rated for that. The maximum power specification for
AM should be observed rather than that for SSB and CW. You can push it
some on PSK because the average power is 41% of the peak power but not
on the FSK modes. A friend of mine recently admitted that he melted his
linear's power transformer during a RTTY contest so cheer up - the
problem can be self limiting.

Actually, we are required to use the minimum power to accomplish the
desired communication.

Larry, KG4Q


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