[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: re: FM Sat Channel Spaceing 15 vrs 25k



Robert Bruninga wrote:
> The correct way to build a 70CM uplink satellite receiver is with
> a wideband (say 45 KHz wide bandwidth).  This is what we did 
> on PCSAT-1 so that users on the 70 cm uplink also did not have
> to tune for Doppler AND they could use their normal 70 cm radios.
>
> The disadvantage of using a 45 KHz wide receiver to avoid any
> doppler adjustments by users on the uplnks is that it ruins the 
> uplink budget by 6 dB.  But this is not a problem at all, since
> users on the ground have 50Watts, whereas the satellite
> may only have 5W.  Again, this is why using all 2m downlinks
>   
<snip>

I still want to know where you keep finding this mythical 50W UHF FM 
modern radio, Bob.  :-)  (Poke, poke...) 

Most manufacturer's are building them 35W or less on the dual-banders 
these days and have been for a decade... an FT-857 will only do 20W on 
UHF, for example.

It doesn't make a huge difference to your argument -- I just giggle 
every time I see you say there are 50W FM UHF radios readily available. 

I think the era of new 50W FM UHF radios is over, with the manufacturers 
going to the cheap and dirty trick of using the VHF PA at UHF 
frequencies, and de-rating it to deal with inefficiency and heat.

Nate WY0X
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home