Short Instructions for AO-40 v 2.1 Excel Spreadsheet:

1. When the files starts, it asks if you want to enable macros, choose Enable. 
2. Choose Mode S2 for Downlink
3. Choose 70cm (if you're not on mode L) for Uplink

The program will then initialize with the last variable set you used. If
you got the file from me with N0AN in the file name, the variables are
set based on my "typical" mode U/S setup as follows:

Rx ant: 39" HyperLink BBQ Dish, 24 dBi Linear 
Coax Loss Ahead of DownConverter (D/C), 0.1 dB
UEK-3000 Downconverter, 0.6 dB NF, 30 dB gain
80' LMR-400 Coax, Loss at 2m, 1.2 dB

Notice the intermediate amps are left out, because they don't exist.
If you have a separate preamp and D/C, you can enter them in the 
boxes provided. If there are no other preamps, etc, make sure to
put 0 for NF and 0 for gain. The last coax loss figure of 1.2 dB
is the loss of the coax from the output of the D/C to the input of
your radio.

Notice the squint is set to 0 for all beginning analysis. Once you
understand how all the other variables work and have successfully
"modeled" your setup, you can start playing with squint and see
the effect that squint has on performance. It gets increasingly
dramatic > 25 degrees.

IMPORTANT: Don't get overly optimistic about your radio's NF and
Rx Bandwidth. The FT-847 may be slightly better than 12 dB NF and
BW of 2500 Hz, but I wouldn't stake my results on it. Better to 
be pessimistic here and if you set all the other variables and then
play with this value, you will see it has very little impact.

The largest single contribution to your receiving capability is the
noise figure (NF) and gain of the first RF amplifier after the 
antenna. If you have an integrated D/C like the UEK-3000, you have
the luxury of a low noise front end and plenty of gain. If you have
a Drake, you don't..you have a mediocre NF and relatively low gain.
The results should be VERY apparent if you play with them.

As you play, change only one variable at a time, after you establish
your "baseline" station conditions, i.e., what your station is really
like. You can then determine where to spend your money. Now...I can 
tell you from a good theoretical basis and practical experience that
your money should go into the preamp and/or integrated D/C. If you 
don't have a NF of < 1 dB and a gain of > 25 dB, you are missing the
boat.

Once you have a decent NF and Gain at the front, you can afford all
sorts of loss behind it. Introduce 5 dB of coax loss instead of 1.2
dB and notice how little effect it really has. On the other hand,
put 1.5 dB or 2 dB of NF and 20 dB of gain at the front (where your
D/C or preamp is) and your ability to hear goes right in the toilet.

==================================================================
The factor that lets you know about your receive capability is the 
S/N of the Main Beacon. It should be close to 20 dB if your system
is good. Remember, you can be no louder than 8 dB BELOW the MB. So
if you have 20 dB S/N on the MB, you can never hear yourself any 
better than 12 dB S/N. (LEILA will get ya!)
==================================================================

Transmit or Uplink Side:

FT-847 barefoot, max of 50 w out, set to 13 watts for starters.
M2 CP-30 RHC Crossed yagi, 14.2 dBC (circular) gain.
80' LMR-400, 2.1 dB loss

Once set up, increase your power and wait for the red LEILA to 
show up...that shows you your limit and the effect of both your
receive and transmit capabilities. Your Uplink S/N is how loud
you are received AT THE SATELLITE, representing the VERY BEST
you can sound, to yourself, period. In the example, I show 
my setup yields 11.8 dB with 12 w of TX power. If I want to get
louder, I cannot increase power or will trigger LEILA. I only
have two choices: Better rx antenna, or better NF/GAin in the 
first RF stage (D/C or Preamp). 

Determining Coax Loss:

http://www.timesmicrowave.com/cgi-bin/calculate

This is a nice on-line or downloadable coax loss calculator.


=====================================================================

Part II - Looking at the Graphs/Display Page

This page is brought up automagically after you make choices for 
Downlink and Uplink frequency.

Entering The Most Common Variables:

Coax Loss (located under Coax Feedline):

This is the connector and short pigtail coax loss between the
antenna and the input to the first preamp or integrated D/C.
It is a VERY destructive loss in that it directly adds to the
effective noise figure of your preamp/DC. It must be kept as
low as possible. Certainly no more than .2 dB

Preamp or Downconverter (D/C)

This is your UEK-3000 or Drake or AIDC DownConverter (D/C) or
the first preamp if you are using a preamp ahead of a sub
optimal downconverter. The UEK-3000, for example would be
.6 dB NF and 30 dB gain. The Drake with no preamp, would be
on the order of 4 to 6 dB NF and < 20 dB gain. Run the Drake
with these numbers against the UEK-3000 and you will see why
so many people using this system in the early days of AO-40
heard so poorly and thought the bird didn't work well. This
first preamp or integrated preamp/DC is CRITICAL.

Preamp or D/C and Coax (Next going Left to Right):

For most setups these are not used and all values are set to
0. If you have a preamp then a downconverter, this set of 
blocks is used. The First Preamp (above) enter your preamp
NF and Gain. The Second Preamp/DC (this one), enter the 
NF and Gain of the DownConverter, like the Drake. It is
VERY unlikely you will be using a preamp with a high quality
D/C. If you use a separate preamp and d/c, be sure to include
the coax loss from the output of the preamp to the input of
the D/C.

Coax Feedline:

This is the long run of coax between the output of the D/C and
the input to your radio.

Determining Coax Loss:

http://www.timesmicrowave.com/cgi-bin/calculate

This is a nice on-line or downloadable coax loss calculator.


Receiver NF and Bandwidth:

Most modern VHF/UHF radios area downright DEAF. No matter how hot
you think your FT-847 or whatever is...it ain't. Assuming anything
better than 8 dB for a NF is absurd, and you are better off leaving
the default of 12 dB for the radio. Bandwidth is whatever you 
actually set it for, assuming you have variable bandwidth. You can
certainly see the dramatic improvement in noise floor (and therefore
performance) by using 200 hz (like for CW filter). This is quite
instructive, but not particularly useful if your only running SSB.

Antenna Gain:

If linear, use dBi, not dBd. dBi = dBd + 2.1 dB.
If linear, put an L in the little box. If circular, put in C

Sky Noise Temp: Don't change unless you are an expert.
Ant Noise Temp: Don't change unless you are an expert.
Satellite Range: 50,000 Km, no need to change until you are playing.
Freq: This is set by the program, when you choose uplink/downlink. 
Sat off point angle (squint): Don't change until you want to examine
                              the effects of squint. Set to 0 
                              
                              
Output Results Table (upper left)

System NF:

This is the result of Sky Noise, Antenna Noise, Preamp Noise, Preamp
Gain, Coax Loss, Radio Noise and Receiver Bandwidth. This figure 
determines the overall receiving sensitivity of your system, without
considering the gain of your antenna.

Receive System Temp:

Just another way of expressing System Noise Figure

(Other variables skipped...they are not for beginners)

Beacon Signal to Noise:

This is the first BIGGIE.  This tells you how many dB above the noise
you should be hearing the beacon. It also tells you indirectly how loud
you can hear yourself, no matter how much power you run. This is 
IMPORTANT:

You can never be louder than 8 dB WEAKER than you hear the beacon!!! If
you are supposed to hear the beacon with a 20 dB S/N, then your own 
signal can NEVER be louder than 12 dB S/N. Period. LEILA (automatic 
power limiting on the bird) is set to trigger if your uplink signal is
any stronger than 8 dB BELOW the beacon. (This is an oversimplification).

If you want to hear yourself better, change your system to get a better
predicted S/N on the beacon...don't change TX power beyond the point that
the program tells you LEILA will be invoked.

=========================================================================

Transmit or UPLINK Section:

Transmitter Power: Enter a value that reflects what you think you need. 
Coax Loss: the loss from your radio to the transmit antenna.
Antenna Gain: enter the value for your transmit antenna in dBi
Polarization: enter L for linear (vertical or horizontal), C for circular
Frequency: this is set automatically by the program when you choose the 
           uplink and downlink bands at the beginning of the program.
           
EIRP: Effective Radiated Power in Watts

This is the Radio Power Out - Coax Losses + Antenna Gain. 

UPLINK S/N: This is the Second BIGGIE

This is how well the satellite hears you. It is your signal to noise
ratio at the satellite receiver itself. The example shows about 12 dB.
Notice how this is precisely 8 dB weaker than the beacon is being heard
by you.

===========================================================================

OK...that's all I can think of in a hurry. I hope this helps. There may be
mistakes in my comments, but most of it is pretty garden variety info. I
haven't attempted to explain every variable. I only covered the ones that
are critical to a beginner.

73, 

hasan, N0AN