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

Re: AO40 MB SNR



Someone asked a useful question:

> how can we determine dB (rather than S-units)?

Easy, if you have any kind of attenuators that are calibrated in dB.
Insert dB in  your feedline until the S meter reading on the signal of
interest drops to the same reading as the noise without the attenuators.

Actually, do this once for each S-Meter reading on your radio and attach
the result on a sticker on the top of the radio...  and then you can
always refer to readings in "dB"...

If one has the following attentuators, you can measure almost anything to
about 1 dB accuracy from 1 to 40 dB depending on which ones you add up...

a 1 dB attenuator
a 2 dB attenuator
a 3 dB attenuator
a 6 dB attenuator
a 10 dB attenuator
a 20 dB attenuator

real handy to have around...  You can make them out of several lengths of
RG-58 with handy connectors on each end.  (But then they will have
different attenuations on different bands... which also might be handy).

Or, just measure the loss in all your favorite portable 50' pieces of coax
you save for FieldDay, mark them, and now you have something you can use
for two purposes... Bob



----
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