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Re: ERP on V and L for AO-40 (Shouldn't this be mode U and L?)??



>From: "Gary \"Joe\" Mayfield" <gary_mayfield@hotmail.com>
>I would argue that 25 W ERiP is completely unrealistic at appogee.  I
>have made my share of AO-40 contacts, and my setup is as follows.  My FT-847
>gets about 25 Watts at 435 MHz  (50 Watts at 432 and 50 Watts at 446.00,
>just my luck!).  I have about 50 feet of LMR-400 UF coax,  I should loose
>less than 2 dB there, but I am going to say I loose 3dB to be safe.
>Cushcraft claims I have a 12 dBi antenna (RHCP), so I will say it is
>probably a 9 dBi antenna.
>
>     My result is 25 Watts into 6dB of system gain or 100 W ERiP.  In
>reality it is probably a little more than that.  I am one of the weakest
>signals on the bird.  Leila is completely unaware of my existence (I would
>like to trip her once just so I could say I did!).  I often will answer CQs
>and the calling station doesn't hear me (I can hear myself so I know I'm on
>frequency).  In my opinion a 200 W EiRP is needed for reliable SSB
>communications.  I do not think LEILA will notice you untill you are well
>above 600 W EiRP.  I believe most of the good signals we work (easy copy,
>but not tripping LEILA or the AGC) are probably right around the original
>design spec of 400 W EiRP.

Glad to hear finally from someone with on-air experience.  The pre-launch
theoretical models are only a guess.

I could not lay my hands on my "P3D to P3G", but from memory I remember
something like 50w into a dipole, so subtracting 3 dB for polarization
mismatch [linear/circular], then the predicted level was 25w EiRP.

Well a freind who actually worked several stations on mode-US played with
uplink power and found that about 25w to a 13 dBi X-yagi [RHCP] produced
very comfortable signals.  He did reduce power to about 3w and found it
usable.  So what EiRP is this.  With several assumptions about his setup:
25w, -2 dB loss, 13 to 16 dBic ant gain gives:  315 to 630w  EiRP.  The 3w
level translates to about 40w EiRP.

His receiving system on 2.4G easily produced beacon signals 30 dB above
noise, so he is hearing very well.  I think you should plan on the average
station not hearing that well.  Also, add some more power for working at
large squint angles [up to 30].

Based on this I would "guess" that a person should aim at a MINIMUM U
uplink of 100w EiRP for cw and probably 200w EiRP for ssb, and the ablility
to increase your uplink by 6 dB for the "hearing impared" and high squint
situations [also for digital].

My UHF system will allow me to run as high as 1700w [50w, -1 dB, 16.5
dBic]; that would be a real LEILA catcher.  I hope to be able to run at 5w
producing 170w EiRP.

On 1269 I will be able to run about 15w at the antenna [20dBi] minus 3dB
polarization loss: 750w EiRP.  It would be interesting to hear from those
who made some QSO's on mode-LS to find out their observations on uplink
requirements.

Ed

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