Viavi 3900 Series Operation Manual page 235

7. 4. 12 .A .5 P re-A mp S o ft Key
Th e 39 00 is eq u ipp ed w ith an in te rna l 1 5 d B b roa db a nd a mp lifie r th a t a ffec ts the T /R a nd
AN T In pu t P o rts. Whe n Pr e-A m p is ON , the 3 90 0 h a s a ty pic al no ise fig ur e o f -9 d B,
re su lting i n a no ise fl oo r le ve l aro un d -1 40 d B m in th e sp e ctru m a n aly ze r ( RB W = 30 0 H z)
an d aro u nd -1 26 d Bm f or t he In ba nd p ow e r m e ter (IF = 6.2 5 kH z) . U se of th e P re -A m p
fe atu re dr am a tica lly inc re as es th e s en sit ivity o f th e 3 9 00 .
NOTE
A n al og D up le x S y st em
Wh e n P re -A m p is u se d, sp ec ial atte n tion is re qu ire d; it is a
b ro ad ba n d a m plif ier an d co uld le ad to sa tu rati on or co m pr es sio n
p ro ble m s i n th e rec e ive r c ha in i f th e s ign a l of inte re st is v er y lo w ,
b ut a s tro ng o ut of ba nd si gn al i s p re se nt.
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