From: mbn@greyskul.hf.intel.com (Mike Northam)
Subject: Re: miscellaneous questions
Reply-To: mbn@hfglobe.hf.intel.com (Mike Northam)
Organization: Shorter Software Solutions
Date: Mon, 11 Jan 1993 21:05:37 GMT

>>>>> "david" == David Leon <dleon@seas.smu.edu> writes:

david> In article <SETZER.93Jan8144823@math.math.ncsu.edu> setzer@math.ncsu.edu (William Setzer) writes:
>Many (much belated) thanks to those who sent me phone numbers of
>mail-order satellite dealers.  After (finally) ordering and combing
>over the catalogs, I have some questions that don't seem to be
>addressed well in any of the literature.  Please reply via e-mail,
>unless you think the readership of r.v.s would be interested in seeing
>the answers.  Thanks in advance for any help.
>
>1) Between the literature and installers, the consensus is that for
>   someone in NC, a 7.5' dish/25 degree LNB or a 10' dish/40 deg. LNB
>   combination gives approximately the same picture quality.  What do
>   I gain if I decide upon a 10'/25 degree combination?  (That is,
>   are there common enough non-ideal circumstances to warrant the
>   overkill?)

david> Personally, I would go with a bigger dish.  If the picture you wind
david> up with stinks, you can easily replace your LNB.  If the picture
david> stinks because of the small dish size, unloading a dish is more
david> difficult.  The 10/25 combo may come in handy for some of those
david> hard to reach birds like Morelos and those Intelsats.

The larger dish will also help alleviate cross-talk problems with the new
2-degree spacing of birds.  The smaller dishes can have problems
discriminating between two closely-spaced satellites--partcularly with
your low look angle for the new C3/C4 etc. birds from North Carolina.

As David says, a larger dish will bring in more signal from the weaker
sats, as well.  If you don't have much signal in the first place, more
amplification isn't going to help much.

>2) What is the significance of the size of the actuator?  (In other
>   words, what advantage is there in getting a 24" vs. 18"?).  Other
>   than price, are there any disadavantages to choosing an H-H instead
>   of a linear actuator?

david> 24" actuators will give more leverage to move your dish around.
david> Think of trying to force a rock to move with a fulcrum.  You would
david> have better leverage with a longer rod, therefore making the move
david> easier with the longer rod.  HH mounts allow the dish to sway all
david> the way to the horizon.  If you want to try to hit the Intelsats &
david> Panam sats, then you will need the HH.  I don't think anyone has
david> ever complained because they didn't buy an actuator arm.

Besides leverage (I'm not sure that's really an issue anyway), the longer
arm (or even better, H-H mounts) will allow you to "see" more of the
satellite arc.  This might be an issue if, for example, you decide you
want to go for the SCPC on C5 (Alaskcom) and certainly for Intelsat.

>3) The FAQ mentions that dual C/Ku feedhorns are actually a
>   "compromise system, with some minor losses".  Is there enough
>   lossage to really worry about?  (I love to roam channels, so I'd
>   like to add the Ku stuff, but not if it's going to cause me a
>   moderate amount of trouble [or interference].)
>

david> I think you will find the signal degredation negligible.  I have
david> heard of international feeds hampering domestic C-band performance,
david> but since I do not own an international feed, I cannot attest to
david> that claim.

There's no reason to not get a Corotor-II in this day and age.  Even if
you don't get Ku initially, you'll want it in the future.

>4) Is there any advantage to choosing a particular type of feedhorn
>   support (buttonhook vs. quad vs. tri)?
>

david> A button hook uses a single arm to hold the feedhorn in place.  Tri
david> uses three arms and the quad uses four.  GET THE QUAD!  When the
david> feedhorn slips from the exact center of the dish (as determined by
david> the mount) your picture quality degrades significantly.  In this
david> instance, four arms are better than one (or two).  You'll probably
david> save yourself a few service calls if you go with a quad.

The quad will be what you want if you have any wind and/or you get Ku.
It's more stable and well worth any extra cost.  Where I am on an exposed
hillside, I even have wind problems on C-band.  I'd be *dead* without my
quad mount during those winter storms.

[munch]

>(Hoping that the FAQ was right in saying that the only dumb question is
> one I don't ask. :-)

In general, my advice is to get the most flexible, high-quality system you
can, in terms of dish, mount, etc.  A few extra dollars spent in this area
will never be wasted, as later on it's easy to add/upgrade IRDs, Ku
capability, LNBs, etc.  It's a lot more trouble to put in a better dish,
etc. at a later time.

As far as dumb questions go, yours certainly aren't in that category.
Maybe they ought to go in the FAQ, in fact.
--
Mike Northam, Shorter Software Solutions, on contract to Intel Corp.
(h) (503) 324-1831 (intel office) (503) 696-4860 (shorter) (503) 357-1010
mbn@hfglobe.hf.intel.com
"You ducks are really trying my patience...but you're SOOO cute. --Apu 9F01
Newsgroups: rec.video.satellite