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

Re: Converter gain and noise..



Hi Jens,

You touched on a subject that has bothered me lately.  I think the
inflated signal reports do a lot to discourage those who are still
working on their receiving system.  That included me until I did some
measurements for myself.  Yesterday I did receive some pretty good
signals for over an hour.  The signal strength indicated on the S-meter
was S5 over a 1 1/2 S-unit noise level but I measured the actual S/N
level at only about 8 to 10 db using an external IF atten.  With my
set-up using an extra down converter to get to 29 mhz from 123 mhz my
S-units in that range are only about 2 db each!.

It really is exciting to me thought to see so many people copying the
signal.  I hope the message gets around to all those I talk to who think
AO-40 is only going to be useful to the "techie group".

73 de Jess - W4MVB

On Thu, 26 Apr 2001 04:18:27 +0200 "Jens H. Jensen" <topcat@hardware.dk>
writes:
>Hi
>
>Have anyone experimented with attenuators on the much famed DRAKE and 
>other 
>converters?
>
>I ask because here on the BB i regulary see people boast that AO40 was 
>so 
>and so many dB over S9 at their site, but a little later they mention, 
>as 
>if in passing, that their noisefloor is S5!
>
>This to me indicates vastly excessive gain for the given 
>noisefigure?....
>
>Doesn't anyone care about large-signal handling anymore.
>Please dont tell me that we are all turning CB-mode, brains off :-(
>
>When the 2.4Ghz band becomes more crowded by commercial signals we 
>will 
>HAVE TO face this problem, i suspect.
>
>73 de OZ1LRG
>
>----
>Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home