For the 40 meter, 20 meter what type of rf pre-amp
stage should be used. ,,,,
any design guidelines, examples , i have made one but i need some practical insight please..... it will be driven to the diode pdm ( product detector module).... de vu3inj...
any design guidelines, examples , i have made one but i need some practical insight please..... it will be driven to the diode pdm ( product detector module).... de vu3inj...
Dev
Rama Prabhu A small 13 dB gain amp would do because of the diode
DBM which is lossy!
Normally the loss of diode DBM is around 7dB to 9dBso excess gain should not be used!
Happy home brewing!
By the by 12 dB gain = 4 times voltage gain!
Normally the loss of diode DBM is around 7dB to 9dBso excess gain should not be used!
Happy home brewing!
By the by 12 dB gain = 4 times voltage gain!
Kalyanasundaram
Ramachandaran Around 10db will ideal.
Indrajit
Sinh should i use high ft transistor c2750 or common bc547 for
40/20 meter front end , calls A,wideband 3:1 balun transformer as
load , secondary connected to dbm......
Dev
Rama Prabhu Better to go for 2N3866 as it is strong signal low
noise amplifier!
Ron
Mallik 2SC3355 will easily work with 30mA of current at 9-10V
Vce. Amazing noise and IP3.....2N3866 very dubious these
days..."printing maal" as per local trusted dealer
Ron
Mallik Indrajit
Sinh and others: IMHO the electronics is not the main problem.
How skilfully you wind your magnetics, will play a big role. For
example, the original designer may have carefully wound the bifilar
coil with say uniform 8 twists per turn and spacing them evenly on
the toroid. The novice did everything, but wound the coils randomly
(anything but broadband ) and did not check for phasing: same
electronics, but it doesnt work in the latter case! Designer gets
bad name but HOW designer will document his skill and experience
Ron
Mallik For 40/20m BC549C is great.....10mA Ic is enough! We
should not also ignore the C9018 transistor. It is a brilliant but
cheap device. The vendor will make a BIG difference
though.....Better to locate Fairchild/Onsemi 2N3904 instead.
Atmospheric and antenna noise is much higher so do not bother about
noise figure at these frequencies!
Indrajit
Sinh i fully agree with Ron Mallik on the toroids winding.
infact i have written on it in my blog. pahsing and twist no
problem. will go for bc549c yes C variety.... as the rx is just for
checking the local signal during the testing phase of the
transitter... it will be use will similar to FSM. i will be
listening on my tic tic and adjust the tx.... as for 2n3866 its a
good one but in the market they sell two variety one cheap and one
guranteed so not buying any2n3866
Indrajit
Sinh for the bad name :: designer has to really write two type
of writings. one as a normal they are doing and one very extensive
one ( like i do with writing down even a trivial thing, the process,
what i thougt and what went wrong and how i got it corrected etc ).
second type of writing we dont see any... that was the reason for me
to re-invent wheel dialogues.... lets hope by doing thought churning
something good will come out... ( i am not a designer just a
reproducer, jugadu...)
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