[amsat-bb] Re: (no subject)
kl7uw at acsalaska.net
Tue Mar 16 13:36:13 PDT 2010
At 11:45 AM 3/16/2010, Jack Barbera wrote:
>Bob,with the AG25 preamp on I see s5/6. I do get the audio at a
>higher level ,it seems to me,.
>Just added to AO-51 the L/u to my doppler for satpac32 FM/FM to add
>for cross mode do I have to add a separate line or add to the info
>on the FM/FM string.
>If anyone can figure out what my ? is pls let me know what has to be done.
>Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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Sorry if this was covered, but do you have an internal preamp in the
radio? If you do, turn it off. Even if there is not one, maybe you
have an attenuator on the input ( a lot of the newer radios do
nowdays). Try turning on the attenuator (probably 10dB) and see if
that sounds better. If you have SSB see what S-meter rise you see in
SSB. My preamps push my S-meter in FM a lot higher than when in SSB
(typ S-5 vs S-2/3). I am running a 22-sB gain 432 preamp on my new
Lindy antenna into a FT-847. The NF is probably approx 0.5 dB (Mgf-1302).
The others gave you methods for testing it with local signals
(measure S-meter rise on/off with a local rptr; compare S-meter with
preamp connected with just the radio connected; moving antenna so
that a local signal becomes near noise level and see if preamp pulls
it up out of the noise (by ear)). Usually a rise in background noise
is the sign of a healthy preamp - but not always. If signals are
heard better without the preamp, then it probably is "broken" (always
check dc power connections in this case). the AG25 is probably
powered thru the coax by your radio (check that the radio is putting
out voltage on the center pin). Since you are seeing noise rise
these latter ideas are applicable (just covering the field for others
that may be having preamp problems).
73, Ed - KL7UW, WD2XSH/45
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
500-KHz/CW, 144-MHz EME, 1296-MHz EME
DUBUS Magazine USA Rep dubususa at hotmail.com
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