[Moon-net] How much gain and where should it be?

[Lance Collister]

Dave Anderson, K4SV wrote:
> Hi Gang,
>  
> Since I am new to EME I have lots of questions.  
>  
> I would like to know How much gain to have, and, Where should the gain be, at the antenna or at the rig?
>  
> I have a very nice M2 H frame with 4 2MXP20's.  It sits atop a 32 foot (10 meter) tower with clear visibility of the sky and I live on top of a hill.  It's feed with Andrew 7/8 Heliax with a few relatively short FSJ4 Superflex jumpers to connect all the pieces.  I am currently using a Icom 910H radio, 8877 Amp and preamp located in the shack.  I get excellent reports on transmit.
>  
> The run of 7/8 Heliax and FSJ4 is no more than 85 feet when you add it all up.  All connectors are Andrew.
>  
> So my first question is 
> Where should I put the 0.3 NF Preamp and its Bandpass filter?  At this time I have a single feed line with Polarity switching at the antenna.  The obvious answer is at the antenna, but, does it really make that much difference considering my low loss?  Putting the Preamp at the antenna requires antenna switching which induces more loss. In the shack the preamp connects easily to the amp relays.  So should it be in the shack or at the antenna?
>  
> So how much gain is needed and/or required for maximum performance?  Is there an optimum gain or convenient gain?
>  
> If someone has played with a similar system layout or has completed tests with the preamps I would like to hear your test results.
>  
> Thanks in advance for all the replys.  I promise to share the results from my questions.
>  
> 73's
>  
> Dave Anderson, K4SV
> Tryon, NC
> 828 777-5088
>  
> www.K4SV.com
>
> _______________________________________________
> Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html
>
>
>   
Hi Dave,

You can very easily model all those various possibilities if you use the 
EME CALCULATOR that is included in the old WSJT VERSION 4.9.8, which is 
still available for download from the WSJT site.  Just select EME ECHO 
for the MODE and you will see a button for the EME CALC right above the 
AUTO IS OFF button in the lower left corner of the screen.  Typically, 
if you have less than 1 dB of feedline loss, you can just keep the 
preamp in the shack.  GL and VY 73, Lance

-- 
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: (406) 626-5728
URL: http://www.bigskyspaces.com/w7gj
2m DXCC #11/6m DXCC #815