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Re: Beacon Strength



Hi all
I have made several noise measurements.  I use a pad an an ac voltmeter on
the speaker leads with the agc disabled.  My station here is a 6 ft dish
linear pole dem preamp and a dem converter feeding a r 7000 .  On 01 11 18
with ao 40 at 59,000 km low squint angle I rx the beacon 20 db above the
noise. I could also see the xbonder noise floor about 5 db above the noise.
the xbonder noise was varying about 3 db.  I estimate my nf is app 1db.  I
also measure sun noise between 5 db to 7 db above the ambient noise. It is
my opinion that s meter reading should not me used to measure anything in
absolute terms.
73 nick k5qxj




----- Original Message -----
From: "Hilton Meyer" <hmeyer@clear.net.nz>
To: "AMSAT-BB" <amsat-bb@AMSAT.Org>
Sent: Wednesday, December 12, 2001 6:23 PM
Subject: [amsat-bb] Beacon Strength


> For some time I have been observing what would appear to be somewhat
> extravagant claims for the strength of the AO40 Beacon. It is my
> understanding that the best level the Beacon can reach above the noise
> floor is perhaps 27 or 28 dB.  Another source measured this as around
21dB.
> My question is how can claims be made for S9+ levels when the standard S
> point unit is 6dB?   I would suggest that a more realistic level claim
> would be dB above the noise floor if this can be determined. With my
modest
> set-up using an FT847 with attenuator on, pre-amp off and noise floor at
> under S1 on the meter, the beacon at best reaches S7.  Signals that don't
> upset Leila are around S4 or 5 which in IMHO would equate to 12 or 15 dB
> above the noise floor.  The S unit on the FT847 would seem to be 3dB?
> Regardless of the size of the antenna if you can detect the noise floor
you
> have reached the practical limit of signal level?  I would appreciate some
> input from more learned persons on this, thank you.
> Hilton Meyer  ZL2MN
>
>
> ----
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