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Dean Williams
July 12th 03, 10:01 PM
Hello all. Having a problem with a new DirecTV install and just
making sure I haven't missed anything obvious.

1) Installed a new triple LNB oval dish
2) One run of RG6 QS coax directly to a new RCA 486 DirecTV receiver
3) Signal strength test shows very strong signal (90) for Sat B
(transponder 28); but I'm getting absolutely nothing from any
transponder for Sat A.

As I understand it, if you're getting a signal from Sat B, you get Sat
A, and vice versa. So, I figured it's hardware. Called DirecTV, and
they said the same thing. So:

4) Replaced the triple LNB head unit with an identical unit. Same
exact problem.
5) Replaced all cables; same exact problem

Called RCA/Thomson, figuring it's got to be the receiver. They
agreed.

Before I replace the receiver, is there anything obvious I'm missing?

Thanks in advance.

Pat Beal
July 13th 03, 08:33 PM
> Thanks for the input. The dish is installed on an existing mast; I
> did check it with a level, and it wasn't perfectly level - the bubble
> was half out of the center. I didn't think this was significant
> enough to warrant re-mounting the mast (a pain given its location) -
> is this small of a difference really the likely cause?

It's pretty difficult to aim a 3LNB dish without a plumb mast. It changes
all the numbers for 3 axes and aiming becomes pure guesswork and luck. Even
with a plumb mast, the numbers supplied for your zip code are only a
starting point for fine tuning.

Pat

Chris Thomas
July 13th 03, 08:53 PM
In article >,
says...
> > I concur. If your mast is even a few degrees off vertical, it messes
> > up the preset elevation and tilt, causing you to get only one sat.

> Thanks for the input. The dish is installed on an existing mast; I
> did check it with a level, and it wasn't perfectly level - the bubble
> was half out of the center. I didn't think this was significant
> enough to warrant re-mounting the mast (a pain given its location) -
> is this small of a difference really the likely cause?

The beamwidth of your dish is about 3 degrees. If "half-way" is more
than 1.5 degrees, then yes, it will matter a lot. Think of pointing
a searchlight -- the beamwidth is about the same. Of course, it
could also be your receiver, or a defective multiswitch. You could
also have a tree or other obstacle blocking one of the sats. The sats
are much higher in the sky than you'd guess from looking at where the
dish is pointing, due to the offset feedpoint. What's your zipcode?

Using a non-vertical mast won't prevent your dish from working, nor
decrease the maximim signal strength obtainable. What it will do is
cause the calibration settings stamped into the sheet metal fittings
to be incorrect. This means you can't rely on the preset settings.
It also means that when you change one of the three settings, you are
in fact also making smaller changes in the other two. With a non-
vertical mast, when you change azimuth, you are also changing
elevation and tilt.

If the tilt and elevation are pre-set correctly and the mast is
vertical then finding one sat by adjusting azimuth finds all three.
If the elevation and/or tilt are off (either set incorrectly or due
to tilted mast) then finding one sat does doesn't find the others.

Find the middle sat (110) and peak its signal by varying the
elevation and azimuth. See if you can hear either the 101 or 119
sats (DirecTV - I forget which service we're talking about). Adjust
the tilt to maximize 101/119 - this shouldn't affect the 110 much
(although it's hard to aviod changing the az/el when working with the
tilt.) Cycle thru azimuth, elevation, and tilt on all three sats and
you should pretty quickly find settings where all three sats peak at
the same place. Remember tilt is the least senstive adjustment, and
won't affect 110 much at all.

When you're all done, your dish will be pointed at the same spot in
the sky as if you'd had a vertical mast. It was just a little harder
to set.

/Chris, AA6SQ

Dean Williams
July 14th 03, 12:24 AM
Chris Thomas > wrote in message >...
> In article >,
> says...
> > > I concur. If your mast is even a few degrees off vertical, it messes
> > > up the preset elevation and tilt, causing you to get only one sat.
>
> > Thanks for the input. The dish is installed on an existing mast; I
> > did check it with a level, and it wasn't perfectly level - the bubble
> > was half out of the center. I didn't think this was significant
> > enough to warrant re-mounting the mast (a pain given its location) -
> > is this small of a difference really the likely cause?
>
> The beamwidth of your dish is about 3 degrees. If "half-way" is more
> than 1.5 degrees, then yes, it will matter a lot. Think of pointing
> a searchlight -- the beamwidth is about the same. Of course, it
> could also be your receiver, or a defective multiswitch. You could
> also have a tree or other obstacle blocking one of the sats. The sats
> are much higher in the sky than you'd guess from looking at where the
> dish is pointing, due to the offset feedpoint. What's your zipcode?
>
> Using a non-vertical mast won't prevent your dish from working, nor
> decrease the maximim signal strength obtainable. What it will do is
> cause the calibration settings stamped into the sheet metal fittings
> to be incorrect. This means you can't rely on the preset settings.
> It also means that when you change one of the three settings, you are
> in fact also making smaller changes in the other two. With a non-
> vertical mast, when you change azimuth, you are also changing
> elevation and tilt.
>
> If the tilt and elevation are pre-set correctly and the mast is
> vertical then finding one sat by adjusting azimuth finds all three.
> If the elevation and/or tilt are off (either set incorrectly or due
> to tilted mast) then finding one sat does doesn't find the others.
>
> Find the middle sat (110) and peak its signal by varying the
> elevation and azimuth. See if you can hear either the 101 or 119
> sats (DirecTV - I forget which service we're talking about). Adjust
> the tilt to maximize 101/119 - this shouldn't affect the 110 much
> (although it's hard to aviod changing the az/el when working with the
> tilt.) Cycle thru azimuth, elevation, and tilt on all three sats and
> you should pretty quickly find settings where all three sats peak at
> the same place. Remember tilt is the least senstive adjustment, and
> won't affect 110 much at all.
>
> When you're all done, your dish will be pointed at the same spot in
> the sky as if you'd had a vertical mast. It was just a little harder
> to set.
>
> /Chris, AA6SQ


Thanks so much for your assistance, Chris - it's much appreciated.

I am going to remount the mast tomorrow - I want to be sure. I've set
the tilt and elevation correctly for my zip code (94941), and while
there are trees, they're about 40 feet away, and low. It is DirecTV,
so the sats your describing are correct. It's got to be the
positioning of the dish, or less likely, the receiver.

I'm very glad I found this board, because I had convinced myself it
was the receiver, and not my positioning of the dish - thanks much.

Dean Williams
July 14th 03, 12:24 AM
Chris Thomas > wrote in message >...
> In article >,
> says...
> > > I concur. If your mast is even a few degrees off vertical, it messes
> > > up the preset elevation and tilt, causing you to get only one sat.
>
> > Thanks for the input. The dish is installed on an existing mast; I
> > did check it with a level, and it wasn't perfectly level - the bubble
> > was half out of the center. I didn't think this was significant
> > enough to warrant re-mounting the mast (a pain given its location) -
> > is this small of a difference really the likely cause?
>
> The beamwidth of your dish is about 3 degrees. If "half-way" is more
> than 1.5 degrees, then yes, it will matter a lot. Think of pointing
> a searchlight -- the beamwidth is about the same. Of course, it
> could also be your receiver, or a defective multiswitch. You could
> also have a tree or other obstacle blocking one of the sats. The sats
> are much higher in the sky than you'd guess from looking at where the
> dish is pointing, due to the offset feedpoint. What's your zipcode?
>
> Using a non-vertical mast won't prevent your dish from working, nor
> decrease the maximim signal strength obtainable. What it will do is
> cause the calibration settings stamped into the sheet metal fittings
> to be incorrect. This means you can't rely on the preset settings.
> It also means that when you change one of the three settings, you are
> in fact also making smaller changes in the other two. With a non-
> vertical mast, when you change azimuth, you are also changing
> elevation and tilt.
>
> If the tilt and elevation are pre-set correctly and the mast is
> vertical then finding one sat by adjusting azimuth finds all three.
> If the elevation and/or tilt are off (either set incorrectly or due
> to tilted mast) then finding one sat does doesn't find the others.
>
> Find the middle sat (110) and peak its signal by varying the
> elevation and azimuth. See if you can hear either the 101 or 119
> sats (DirecTV - I forget which service we're talking about). Adjust
> the tilt to maximize 101/119 - this shouldn't affect the 110 much
> (although it's hard to aviod changing the az/el when working with the
> tilt.) Cycle thru azimuth, elevation, and tilt on all three sats and
> you should pretty quickly find settings where all three sats peak at
> the same place. Remember tilt is the least senstive adjustment, and
> won't affect 110 much at all.
>
> When you're all done, your dish will be pointed at the same spot in
> the sky as if you'd had a vertical mast. It was just a little harder
> to set.
>
> /Chris, AA6SQ


Thanks so much for your assistance, Chris - it's much appreciated.

I am going to remount the mast tomorrow - I want to be sure. I've set
the tilt and elevation correctly for my zip code (94941), and while
there are trees, they're about 40 feet away, and low. It is DirecTV,
so the sats your describing are correct. It's got to be the
positioning of the dish, or less likely, the receiver.

I'm very glad I found this board, because I had convinced myself it
was the receiver, and not my positioning of the dish - thanks much.