We come to the practical test, we test the receiver with preamplifier
which is a straight receiver
The straight receiver without preamplifier does not work
The detector receiver is not because I have not fitted an NF amplifier works, no driver
we did receive stations with the detector receiver
but they were so quiet that we could represent not really good on camera
and now we are testing times the receiver with RF preamplifier
I connect to only times the
the circuit with Plus
so and we previously had been a station set
can also make a little louder if you want
and the variable capacitor, we can now tune into another station
Here another transmitter
Yet another transmitter
Today, quite a few stations on medium wave
so now we test the straight receiver
the difference to the detector receiver is that the diode is biased in straight-line receiver
that is, the diode is already in the conducting state
we are using a silicon diode instead of germanium diode
the detector receiver, the receiver must indeed
since we have the diode
the receiver part must indeed the high frequency swing open so strongly by the resonant circuit
has such a high voltage that caused the diode is just conductively
and in the event the diode is already conductive, and we have a higher sensitivity
In addition, if we already have a supply voltage
we have a 2-stage RF amplifier still switched to transistors 2
the just then correspondingly high level Hf at the diode provides
and so we get a very sensitive detection receiver
then we feed the circuit with current times
and we already hear
we are now on the straight receiver
set at the transmitter variable capacitor
can a little louder to make it better listen
strong stations are very loud, at the coil, we can also adjust the transmitter
yes, we also have three stations ... at least
ok, now we come to the Audion
Audion is a straight amplifier with feedback
we supply the Audion circuit times with current
and
We have already
a transmitter
However, too much feedback is still set so whistles it a little
but is already really loud
so then attempt times adjust the feedback
I take time off to something
now it is quiet
so it's really fingertips feeling demanded so
adjust feedback is difficult but
now we have less feedback
when we are on the transmitter exactly it
the so-called swing Bungs zero
but we make a little less feedback
it works now
perhaps adjust the frequency as best
yes I think you can hear it quite well
ah now we have set the frequency accurately
yes you can hear it quite well
so great ... One other stations can set but
which is currently the strongest transmitter
and other transmitters are even more difficult to adjust because they are weaker
and also quieter
because there is missing an amplifier stage between the Audion and the power amplifier
ah we still have a strong
is still a little feedback on it
that is the drawback when one adjusts the frequency
would have the feedback each tighten again
but it goes like this actually
yes, works well
Thunderstorm is also how to listen
ah, we have thunderstorms again, ok
so now we have rebuilt a straight receiver here
this time with 3 transistors, So 1 2
3 and then the NF continues, the antenna we have at the input circuit tuned
and the transistor receiver is actually just the superheterodyne
only modified, we completed the superheterodyne the local oscillator
therefore the local oscillator oscillates but is not connected to the mixer
then we have the IF transformer stolen the parallel capacitor
therefore it is him really care what frequency goes by so previously had the
a sharp resonance so 455 Khz when properly calibrated, now
now simply all possible frequencies can be carried, which is the matter
further we have the IF filter stole the mass
thereby the otherwise as a coupling capacitor
and, yes, we now have actually by a straight receiver with 3 instead of 2 transistors
we thought we just run times before and the Eflose makes now
so then we look times
we times the transmitter, making perhaps a little louder that one hears something
we have a station here
then here's a transmitter
again the transmitter with echo, which we had previously been
being the sender with echo, exactly
and another transmitter
exactly now you can still show that
that the signal LED also works
Thus, the LED indicates when a signal is received
LED signal to
it now sees the modulation, one sees that the flashes
yes we can precisely adjust the transmitter, or we take the other stations
Hammer what's in music comes on medium wave
since we do not have anything, an empty carrier but it is a signal that
you can see on the LED
is strong, and the echo transmitter
yes we have 3 channels
so now we are going to rebuild the whole thing for superheterodyne
Plus we make only times the volume
or even let the volume as it is, so
the first thing we add is times times the mass of the IF filter
thus we have ever seen a filter of only 455 Khz can by
then give the transformer to improve the parallel capacitor to the filter
to make narrow bandiger
the IF transformer has been adjusted in advance
so now the whole thing is still not working, we still hear the station extremely quiet
because simple enough HF is there which as just sort of cheating by if you will
to top it for superheterodyne to build we add the local oscillator
and already we have another station
if we make a little louder maybe you can hear him better
so we can let's see what we receive so that
because we now have a nice effect but we show later
We have a signal, make time louder
distorts the extremely strong in front of him
we show afterwards what you can do about it, now we'll see more if something else goes forth
you can also turn on the coil, so that you can move the area from the local oscillator
with this tunable coil next to the Dreko
so now you're right down the frequency range
well we can go higher
Simply Schauben out again
but then must also Dreko from the input circuit at approximately half capacity
because you have the input circuit now calibrated to very low frequencies
since we have a station from England, right?
Now we are on higher frequencies
You can play something with the input circuit
perhaps the reception brings improvement
well the signal is eh already S9 because if you will
which is now the input circuit? I agree
can turn there times
oh there will be even worse
override
now you have adapted it fails now but will it before it was even worse
it was even quieter
yes if you want the signal adjusts the input circuit fails weaker
because it is really bad
because it is very bad indeed
the distorted now, the distorted and the LED lights permanently
and how do we solve the problem? We need to make signal weaker
but that does not make us that we can make the electronics
and the electronic means: Automatic Gain Control
We have an output, a control output from the AGC and
and we have a control input to the receiver is interested in the AGC
and now we hear something happens when Eflose activates the AGC module
connect the output to the input
aaah
plug the AGC again from that you can hear the difference
unplug and reconnect
already works
now it no longer distorted
the transmitter no longer distorted, which has indeed previously heavily distorted
You have to match the input circuit times
the you need because after Syndicate
distorted extreme but with AGC it sounds good
yes, no longer distorted, super
now that was the superheterodyne with AGC
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