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Tuning conundrum



At 06:11 AM 12/16/1999 -0600, you wrote:
>But in the absence of a computer tuning on both sides, please people, please
>let's do what all the books say: TUNE THE HIGHER OF THE TWO FREQUENCIES
>regardless of whether its uplink or downlink.

In general, I agree, and this is what I try to do.  But here's a real-world
situation where this rule can't quite be followed slavishly.  

What happens when working "split mode?"  Say we're on RS-13.  Operator #1
is using Mode A (144 up, 29 down), and Operator #2 is using Mode K (21 up,
29 down).  I think that in this situation, Op #2 might do better to tune
his 21 MHz uplink, even though it's lower. That way he won't constantly
undo Op #1's tuning of 144 MHz.  

Fortunately 21 MHz doesn't Doppler shift so much. But if you follow the
"tune highest frequency" rule, there will be a bit of jumping about, and/or
someone will end up having to tune both frequencies.

I suspect we'll run into this more on P3D when multiple transponders are
turned on.  And they probably will, for backward compatibility with current
Phase III operators. Not everyone will invest in microwave installations
until after P3D is up and the transponders are actually working. 

Consider the combination of old Mode B (435 up, 144 down) with Mode L/S
(1.2 gigs up, 2.4 gigs down).  Or even worse, suppose both operators
transmit on 435 MHz, but one receives on 144 MHz and the other receives on
2.4 gigs.  

I suspect in such situations, we may develop a convention that one operator
will adjust uplink while transmitting and downlink while receiving.  Or, we
will develop a universal rig control package for constant frequency at the
satellite, and have always-perfect keps.  :-)

73 from KD7MW



--- Peter
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