I have e;pained this transmitter be(ore+ but I wi make a brie(
summary. !oi :" is to tune the transmitter to desired(re@uency. It
is (or (inetunin) the transmitter. !rystas do have a itte error in
(re@uency. ?ou can chan)e the(re@uency by some "#th o( kioherts. !"
and :/ is a resonans circuit and shoud be in resonans at ,-. : and
the"#pF and the .< pF capacitors is aso tuned to ,-. This (iter
ceans up the si)na be(ore it )oes to the FCTBF/>&B.The FCT
is workin) as a (oower+ it doesn*t ampi(y+ it just boost up the
current. I have made a si)hty chan)es byrepacin) the source
resistor with a coi. I noticed that I coud )et more power out o(
this FCT with a coi than a "kresistor. ?ou can pay a bit yourse( to
(ind the best output power. 2e;t sta)e is a booster. The reisistor
4/ set the
current and the )ain o( this booster. A to ow vaue wi increase
the current and you mi)ht end up bowin) thetransistor. I usuay use
/#%"##ohm. A dissadvanta)e is that the current consumption wi
increase and i( you are usin)battery it wi be empty (aster. The
current consumption in the emitter is not proportion the output
power.
!onnect a ohm resisitor in serie with a "#nF capacitor and
connect the capacitor to the coector and the resistor to)round.
on*t connect the ast sta)e yet. 2ow you can measure the output
power over the ohm resistor. I use anoscioscope and then I pay with
the vaue o( 4/ and I aso tune !" and : (or best output power. In my
measurementI come up to about "7m$ into ohm with 9' ! in this
e;acty construction.
2ow it is time to connect the ast sta)e. ?ou can aso pay with 4
to set the desired output power. Be car(u becauseit is very easy to
bow the transistor. ?ou can )o down to / ohm + but the current wi
be hi)h and the transistor is notmade (or so hi)h current and it wi
probaby )et hot. I( you use & ohm the transistor wi not be hot
and the tota currentconsumption wi be about /mA and you we )et over
"##m$ o( output power. The ast thin) you wi have to tune
is the antenna (iter.
Tune the antenna (iter (or best D$4. I don*t have such unit but
a transmitters are most o(ten buit to work with areciver. I have a
receiver with a 4DDI indicator5stren)th meter8. $hat I do is to put
the receiver a bit away (rom thetransmitter and I connect the
4DDI%vota)e to a ar)e dispay so I can be severa meters away (rom
the receiver andsti be abe to see the 44DI%vota)e eve. Then i sit
there and tune the transmitter ti I )et the best stren)t. 2ow Ireay
know that my transmitter is tuned (or best per(ormance+ speciay
with that receiver.
