[amsat-bb] Re: Why preference for mode J?

[Frank Grossman <71042.1303@xxxxxxxxxxxxxx>]

Hi Bob, Tony, et. al.,

>>About 9 dB to an omni receive antenna.  This is why it is so much easier
to receive a satellite mobile or at home with an omni antenna if the weak
downlink is on 2 meters.  There is a 9 dB advantage.  This is why we are
advocating a 2m downlink for our mobile statellite APRS system.

> receiving 435 MHz here in the Los Angeles is much easier than 2M due to
> the much lower noise floor.  <<

Another issue is that dual band/full duplex HT's I know of (sold in 
North America) don't transmit below 440.0 out of the box, and not everyone 
wants to open up these small portables and physically modify them for a 
variety of reasons.  The mod. for my Alinco DJ-580T is supposed to be 
relatively trivial, but I have yet to find someone locally who is willing to 
risk helping me actually do it. -s-  I have a second HT (FT-811) that will 
transmit below 440, and that's what I used to make my first ever satellite 
contact on SUNSAT.  it's certainly easier, though, to work satellites that 
let me operate by holding just one HT.

BTW, do you know of any dual band full duplex HT's that will transmit over 
the entire 430-450, and of course 144-148 frequency ranges without hardware 
modifications?

73,
Frank
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