From: dleon@seas.smu.edu (David Leon)
Subject: Re: miscellaneous questions
Organization: SMU - School of Engineering & Applied Science - Dallas
Date: Sat, 9 Jan 1993 05:13:51 GMT

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?)
>

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


>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?
>

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

>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].)
>

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


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

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


>5) What is the difference between the Orbitron C10 and SX10?  There is
>   a $100 difference, but none of the ads really explain why.
>

I think one is a high wind model and the other is an el cheapo model. I
have used a Unimesh for about two years.  Aside from numerous hail pings,
it has held up nicely.  You may wish to splurge on your dish, as it is
probably one of the most difficult to replace.  You can always sell an LNB
or IRD over the net quickly, but a behemoth dish is harder to move.


>6) Last, but certainly not least, the number of IRD manufacturers is
>   truly staggering.  For the most part, I believe that high-end
>   components have all of the necessities, so it comes down to
>   choosing the one with the best set of features.  Unfortunately,
>   many of the ads use "lingospeak" to describe the features, making
>   it difficult for people like me to figure out exactly what the
>   IRD's do.  (I mean, exactly what good are TI filters anyway?)  Is
>   there any good way to filter through the chaff to get to the good
>   stuff?  Are there any manufacturers that I should stay away from?
>   Any help you can give me to narrow my choices would be greatly
>   appreciated.
>

TI=Terrestrial (sp) Interference.  Depending on where you live, this may be
a significant consideration.  I originally had a Toshiba IRD.  The TI in
my area was so bad that I could not watch several channels per satellite,
even with the TI filters enabled.  A switch to the Chaparral IRD fixed that
(they have the BEST TI filters).  Since your IRD is thing you will have to
deal with the most, make sure you get one you like.  I am really glad I ended
up with the Monte, lots of interesting bells and whistles.


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

David 
dleon@seas.smu.edu