[BC] "Cusp Rotation"

[Mike McCarthy]

Actually, I have asked and they HAVE provided the information when I said 
those who do provide the information immediately are those which are 
included in the bid list.  That gets their attention real fast.  Harris is 
petty consistent with their network rotation at 225 Deg.  BE will vary 
slightly and Nautel will vary considerably by frequency.  We just went 
through a complete build and the #1 question I had from our consultant was 
which TX we would use so they could factor in the delay scheme into the 
phasor and ATU designs.

We tuned it with a network analyzer which I bought last year in Vegas while 
at NAB.  It took us one night to completely tune a three tower array (both 
omni and DA modes) so the TX could operate into a 50 ohm load and a 2nd 
night to optimize. Consultant was here only three and half  days, and of 
those, one and half was spent running radials to check the real pattern 
against the model. Can't beat that with a stick.

If you had problems getting the thermal emission spec from CEC, then you 
were not speaking to the right people.  I've never had a problem with that 
type of information.

MM

At 09:48 AM 3/16/2007 -0700, Kent Winrich wrote
>You are expecting the manufacturers to provide this info??? HAHAHAHA  They 
>dont know half of what they put out.  Heck I couldnt even get a simple 
>thing like BTU output from Continental for their 816HD (you know so I 
>could spec out an HVAC system??) let alone a bunch of measurement points 
>on their own transmitter.
>
>I like the idea of your Vector analyzer.  Sure would be easier than going 
>through the OIB and what have you that I did for my two HD installs.  UGH.
>
>Kent Winrich
>
>
>On 3/13/07, Phil Alexander 
><<mailto:dynotherm at earthlink.net>dynotherm at earthlink.net> wrote:
>This whole "phase rotation" / "cusp rotation" business
>drives me slightly nuts, because what we are really
>attempting (as best we can) is indirectly "de-rotating"
>or moving the **actual** PA load at the true output of
>the PA to R = x j0 at the operating frequency with the
>sideband frequencies "horns up." Where "x" is the true
>output resistance of the power amplifier(s). IOW it is
>almost like what we did by tuning and loading a tube
>box "back in the day" by operating slightly off
>resonance for best load to yield best modulation b/w,
>except today we must approximate it and set it in the
>blind.
>
>What is really needed is for manufacturers to include
>a dynamic measurement point(s) for the **actual**
>dynamic, complex impedance across the range of operating
>frequencies as seen at the **true** PA output before
>combining/matching to the Tx output spigot.
>
>That is to say something approaching the idea of a
>**true** PA load sample that might be read by a RF
>vector analyzer.
>
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