[amsat-bb] Re: How much is enough?.

[Clare Fowler]

The proceedure I follow is to ALWAYS wear HEADPHONES and
CONTINUOUSLY MONITOR MYSELF.  I set my tx/rx to the uplink
and downlink freqs shown by SatPC-32 and will be on within a few
hertz so I dont have to go up and down the transponder finding myself.
I also have an SWR/Wattmeter in line all the time.
I adjust my power to a bit bellow the point where I no longer
hear an increase in my signal comming back.
As the qso progresses I continue to adjust the power up or down
to keep my signal at the point that if I reduce it farther I hear a
definite drop in my signal comming back. For VO-52 the max power
I need is about 20 watts (unless some strong alligator is on in which case
my return signal will be very much reduced and increasing my power up
to 50 watts or more will still result in an increase in my return signal)
and the minimum is the lowest that the FT-847 will go which is about 1 watt.
For AO-07 the uplink power can be anywhere from a 100 watts from my amp
and still be just above the noise level to as low as 10 watts for an S7
return signal above noise level.

Operating on a transponder is not not like working HF or a repeater where
it is push to talk.  It is much more challanging, to tune for doppler, 
adjust
az and el rotors and power.  You can automate the first two but the power
is a manual adjustment.

Clare VE3NPC

----- Original Message ----- 
From: "John Hackett" <archie.hackett at hotmail.com>

> ........................................................................................................................................
>
> POWER. How much is enough? .                       La2qaa Feb 2006.
>
> There could be many answers to that question but the correct one regarding
> amateur satellite communications is ...
>
> "Just enough to maintain effective communications".
>
> For instance, how many people reduce their power as the satellite they're
> operating on approaches TCA ... (time of closest approach) ... a good
> operator will, because they know that the use of excessive power is *not*
> good for the transponder. Case in point. When AO-7 first comes up over the
> horizon you'll probably need "X" amount of power to communicate
> effectively.
>
> However, after 10-15 minutes, as the range decreases you'll find that a
> 3dB
> ... (50%) ... reduction of power will have no effect whatsoever on the
> signal. A *VERY* sensitive S-meter might show a difference but your ears
> certainly won't.
>
> Hands up those that actually regulate their power to maintain effective
> communications ... (No, I didn't think so) ... you should try it sometime,
> you might get a surprise.
>

>