New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1922-08-13
How the Super
! Regeneration
Is Adjusted
Detailed Description of ihe
Best Method of Tunin
New Invention of Maio
Armstrong Successful
Shrill Whistle Is Guide
Experimenting Can Be Don
With the Resistances i,
Filter Circuit Syster

SAaJ1E f. H. Armstrong gave OUT <IH
complete details of his er-regenera
tive system to permit radio fans t
construct set enbodying it's prir
ciples. In fact, many have alread
commenced to experiment with it wit
varying success.
Judging from the correspondence
that have received it is quite clea
that the new sets are by no mean
understood either in theory or in op
Grafton, and so / am going to outlin
some of the salient points that must b.
observed before success can be OBJ
tanned with this system.
In the first place, it must be clearly
understood that the experimenter is
dealing with something that is entirely
different to all previous practice, and
consequently. must not allow his ex-
perience with regenerativc sets to be
his guide in operating the super-regen-
erative.
First Tube Is Regeneration
The first thing to do after going
carefully over all of the connections in
the set is, Of course, to turn on the
vacuum tubes. The function of the
first tube is that of regenerator of
the high frequency currents that are
received from the distant station, and.
to certain extent, this tube operates
similar to the regular regenerative set,
with the exception that its filament
must De turned on full. instead Of
Delng held down to keep the tube below
the oscillating point, as is the case
IN the regenerative receiver.
As soon as the tuhes bava baar
turned on to full brilliance, the vari-
able condenser, which is in series with
the l,250-turn and 400-turn duo-lateral
coils. must be varied until a very high
pitched, continuous, shrill whistle is
heard in the telephones. There can
be no installing this sound. 1t is not
IN any way like the varying whistle
that IS sometimes received on re-
generatIve set. 1t is absolutely in
variable in its pitch and continuous in
It's operation.
When this shrill whistle is heard. the
experimenter will then know that the
second tube or osciilator is function
ing perfectly, and the set is ready to
De placed IN the super-regenerative
condition.
Tune TO Wave Length
Having done this, the next adjust
ment Is that Of tuning to wave length
OF the incoming signal. This is done
ny means of the condenser, which is
coupler and the loop aerial.
1t will be found that as soon as this
condenser is turned beyond the wave
length OF the station desired to- be
heard, terrific roar will be heard in
the telephones, absolutely unlike any.
thing that is heard on any other set
~ VIII be necessary to GO back on the
condenser scale.
Having obtained the signal by mean
81 varying this condenser, the next
thing to do Is TO adjust the amount
of regeneration. This is done bv varv.
ing. the position of the rotor In the
Vaffo-coupler. Here again it will be
observed that when too much regen-
GRAFTON is placed in the circuit the
terrlflc roar mentioned above will also
be heard, and it will be necessary n
very carefully adjust the rotor In or
der to eliminate it.
Adjust Very Carefully
IN both the case Of the tuning con-
censor across the loop and the rotor
coil 1t will be necessary to make ad-
justments very carefully and yerv
slowly. 1t will be found that while
'hese adjustments are not altogether
critical there is very critical point
and consequently it will be necessary
to adjust very slowly and very care
fully for it.
AS soon as this section of the set has
been placed in stable condition the
music will be heard very clearly. with
the exception Of the shriI whistle
5nss comes from the oscillating tube.
Ihis whistle cannot be entirely elimi-
mated, although it can be somewhat
rsauceo IN intensity by increasing its
4 pitch slightly by means of the con-
denser between the two coils men
toned above. ~ eA'-
thls shrill whistle is Just below that
point that marks the dividing line be-
tween human hearing and silence.
1he litter circuit which follows the
oseillating tube is designed for two
purposes First, to eliminate, as much
as possible, the effect of this whistle,
go far as audibility is concerned, and,
second, TO prevent the terrific current
lying the simplifying tuba connected in
the three-tube set.
Wave Trap Can Be Used
70 is quite possible that this same
object could be obtained by using a
as wave trap" This is nothing
more nor less than an inductance with
capacity shunted across it, which is
tuned to the frequency OF the current
that IL Is desired to eliminate, so that
results might be obtained by using a
honeycomb coil with condenser
Joined across It. Of sufficient inductance
and capacity to get into resonance with
the 2o.oo0-cycls current produced by
the osciliating tube.
Of course, If this Is used, IL will be
necessary to shield the honeycomb
coil from the other large honeycomb
coils that are used in the circuits
about the oscillator tube.
Another thing for the expertmenter
60 work out for himself is the cor
rect amount of resistance in this filter
circuit. 1t may De found that better
results can be obtained by much less
than the $4,000 ohms suggested by
Major Armstrong. In fact, in recent
circuit constructed by the major, he
has placed the two 10000 ohm units
Ia parallel with each other, which, of
course, cuts down the total effective
resistance in the circuit TO 5000 ohms.
and better results were obtained under
the special circumstances in which this
particular set was used.
While tuning In with this SEE, all
kinds OF weird noises will be heard.
The experimenter must not be dis
couraged over these, but must set
about the task Of learning the cause
Of each one as we'll as the best way To