Hi

If you only have one sat to look at, horizon view is worse than overhead. With multiple sats you want them spaced out over the sky to get a benefit from triangulation.

More TBolt opinions (there are lots of us and we all have them ...)

The wonderful thing about a TBolt is that it can use foam core TV satellite coax. Since 75 ohms is lower loss than 50 ohm (all else being constant) you can get away with quite a bit of the stuff. F connectors are easy to do wrong, so get some good ones and a proper crimp tool.  Most antennas are TNC or N, so you will need an adapter. Again - get a good one.

Keeping the antenna away from traffic is your first goal. Up in the air is one way to do that, far from the house is another way. Last choice would be near the dinner table. Good view of the sky down to about 20 degrees off the horizon is ok. A view to 10 degrees is slightly better. Don't worry a lot about a view towards the north pole if you are in the northern hemisphere.

Run the unit constantly. The OCXO will settle down that way. The holdover training will work best that way. The power required is pretty modest. Mounting the unit in some sort of enclosure is an excellent idea simply to minimize accidents. The power connector needs some protection from bumps and snags.

Where ever you mount the unit, consider that they tend to multiply. You may soon have three or even more than twenty.

So much fun.

Bob

On Mar 16, 2011, at 5:15 AM, lists@lazygranch.com wrote:

On Wed, Mar 16, 2011 at 4:51 AM, Bob Camp lists@rtty.us wrote:

What you really care about with antenna cablbe is the total loss.
Given the gain on the antenna and the requirements of the t-bollt
reciever you have a budget in dB to work with.  Stay within budget.

Loss comes from two things (1) any cable will have a loss measured in
DB for foot at the 1.5GHZ frequency.  This and your budget will limit
the length of cable you can use.  If a given cable type has to much
loss then you need to buy the more expensive kind.  If you are lucky
you might be able to use that cheap RG8 cable TV stuff but if you have
a lower gain antenna and a longer run of cable then you might need
LMR400 at 4X the price.  All that matters is that you keep the loss
in-budget.    (2) connectors and adapters have loss too.  You get the
least loss by using the correct ends on the cable so no adapters are
required.  It all depends if you need to care abou the last dB of
loss or not.

I think the best setup is to put a 1" iron pipe on the roof that is
taller then any other vents or pipes up there but not so tall you
can't reach and work on the top.  Mount the antenna on that pipe and
run the cable trough the pipe, through the roof and then straight down
to the living space in the house.    Ideally the antenna cable run
would be a short perfectly vertical run but that is unlikely.  But
still you want the t-bolt in the living space and the antenna high on
the roof and the cable run minimized.

Once you know the length of cable then you can decide on the lowest
priced cable that still has a low enough loss.

--

Chris Albertson
Redondo Beach, California

Chris Albertson wrote:

Isn't that an invitation for disaster in a thunderstorm? I'm sure the US has some definite rules on how such things need to be set up and grounded.

Cheers
Stefan

On Wed, Mar 16, 2011 at 10:07 AM, Heinzmann, Stefan  (ALC NetworX
GmbH) Stefan.Heinzmann@alcnetworx.de wrote:

Sorry I was thinking only about engineering, not practical maters.

Yes, you are right, there is more to it.  The rules are all local, the
US does not have a national statute. So you need to check with local
building department.  But yes all antenna masts must have a ground
wire.  You'd put a wire and a clamp on the pipe and lead it off to a
ground.  Some will go further and place a lightening arrester in-line
with a antenna cable.  But in most places the local code only requires
the mast be grounded.    Nothing will protect from a direct hit, for
that you'll need a metal tower separate from the house and an
elaborate grounding system on the tower.  But a simple grounded pipe
mast is no worst then the vent stack on a gas furnace.

The other safety concern that must to told to anyone putting up an
antenna is to look for overhead power lines and be 100% certain that
even a huge storm could never case the mast to fall onto a power line
or come even close to one, even if the utility pole falls and your
mast falls

And while we are at it.  There is a danger of falling from the roof.
Always use a safety harness if you are 6 feet above ground or more.
and never work on top of tall building or towers alone, have a spotter

Did I leave anything out?

--

Chris Albertson
Redondo Beach, California

Hi

Every place I have lived here in the US wants you to put a simple ground block on the antenna lead. It's not much of an arrestor compared to the "real thing". Since the auction sites will sell you the right part for less than $20 (at least they used to) there's not much reason to "do it wrong".

Bob

On Mar 16, 2011, at 1:07 PM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:

On 3/16/11 6:55 PM, Bob Camp wrote:

here's the problem.... the NEC (national electrical code, not Numerical
Electromagnetics Code) has 3 sets of low voltage grounding requirements
in article 810,820 and 830.  The rules for Cable TV and dish antennas
are different than for "radio receiving equipment" and which are
different from those for "telephone"

But yes, grounding the shield meets the code in general.

Otherwise, you need a "listed antenna discharge unit"

Remember that the NEC is really designed to deal with "power line to
antenna and support" faults NOT lightning (which is a different NFPA
code).  And the NEC cares not one whit whether your equipment survives,
as long as it doesn't catch fire.

Thanks Bob!  Alot to digest but a good starting point!

Sent from my iPhone

On Mar 16, 2011, at 4:51, Bob Camp lists@rtty.us wrote:

Hi

It's not all that crazy. Unless you are going to buy a new home, there are a limited number of antenna locations possible. With almost any antenna, higher is better, and higher is harder to do. GPS is no different than most things in that respect. People do get TBolts working with living room antennas.

The biggest issue is the "keep it on all the time". I'm not sure a UPS is worth the money in this case, but a dedicated supply certainly is.

It's a hobby - have fun!

Bob

On Mar 18, 2011, at 8:43 PM, Shawn Tayler wrote: