New-York tribune., 1922-03-05
A. D. Newark \. L.

V.~~ls 1T better to shunt the grid leak
across the grid condenser than to r,r
u from the filament to the grid? WHY?
A grid leak is sometimes connsc.ed
from the oscillating circuit side of the
grid condenser to the filament ;nstc.d
OF just across the grid condenscr. .rh;.
Is used only in cases OF very hard
vacuum tubes. however
r. W. H., Brooklyn:
Q.--Is have four-stcp resistance
amplifer, using Importance coils for
res'stances. VIII this set operate on
p'iotrons, provided that my filaments
are bright and use 10 volts ON NV
plate? My bulbs are swat radio
irons A.-Yes, if you place small
variable reslstanccs in the flament cir
cut to give a slight negative charge
to the grid, and also provided that tho
impedancc coils have the proper re-
actance value.
j. {. McP., Short Hills, N. j.:
Q.-Would it be nossib]e 10 cons+,,o4
q 'oose coupler on rectangular tubes?
A.-Ics, but ii would not be as nracti-
cal. Circular tubes are used because
they are more easily handled. operated
and built.
Can't Improve Crystal Set
S. I. NJ. New York:
Q.-l now have a crystal set, "a fol-
lows: Loose coupler, dctcctor, fixed
condenser and two 1,Oo0-ohm nhone.
What should be my next move to i'm
prove this set? If cannot improve it
what apparatus is needed for fairly
good regcnerative set: How far could
this detect music? h-Thcre is no
way | know Of Improving a crystal set.
There are three ways of obtaining re-
generation, but two OF them are best
for short-wave work. One employs a
vsrlo- coupler with ticker coil and
the other vario-coupler with a plate
and grid variometcr. The other parts
needed for this set include a variable
condenser for the secondary Of the
vario-coupier, grid leak and grid
condenser, one V. T. socket and V.
t., together with A. and B. batteries.
You can employ your present tele-
phones and fixed condenser in the set.
A single wire aerial is sufficient for re-
ceiving, and as your ground lead is so
long your present aerial should be
sufficient.
F. H., Bensonhurst:
els bakelite tubing better than
cardboard tubing for primary of
loose coupler? If so, in what way is it
better? A.-Bakclitc is much better 1t
offers higher insulation qualities, and
it will not absorb moisture, warp or
shrink. 1t also Offers constant tuning
qualities, and there is an absence Of
the capacity effect occasioned in card
board tubes by the absorption Of mois-
ture.
No Aerials Across Street
Q.--Arc you allowed to put ono
wire aerial across street? A.-No.
Q.-~I have heard that there is 2 way
to cut out spark stations and still get
telephone By using g. variable con-
denser. Do you think this is possible :?
A.-To a certain extent it is possible
to cut out spark stations by placing
choke coil with condenser across it
in series with the aerial, provided the
choke is Of the correct value for the
station desired to eliminate. Ii the
spark station is very close to you there
is no hope.
H. N. W., Brooklyn:
Would like to use 110 Y. A. C..
etepdown transformer for lighting the
ilament Of The sudion, but find con-
tinuous hum occurs. Can you suggest
any remedy for this? If so, could it
be used with a vacuum tube and one
SET of amplifcation. using regenera-
tive receiver? A.-You might be able
to eliminate the hum by means Of r
filter condenser FOR the detector alone,
but where you use amplification you
will not get satisfactory results. There
is no real substitute for the storage
battery. You can use your A. c. cir
cult to charge the storage battery pro-
vided you have a suitable rectifer and
transformer.
G. +. S. jr, Newark, n. j.:
Q.-How does regencrative set,
composed Of vario-coupler with vario~
meters in the grid and plate circuits,
compare with regenerative set made
up of honeycomb or duo-lateral coils?
Which is the better type as to selec-
tivity and range Of wave lengths? A.
The variometer circuit is best for
short waves only. The honeycomb and
duo-lateral coils work best on waves
above six hundred meters, although,
of course, they will give results on