Evening public ledger. [volume] (Philadelphia [Pa.]) 1914-1942, 1922-05-23
~ VIEW

Every beginner in radio, who starts
out with q crystal receiver and then
graduates to a bulb, using his loose
coupler or his spiderweb coils for the
'single- circuit" hook-up. which We
have already given, longs for the time
when he can afford the regular short
wave regenerative" set, with two vario.
meters.
But variometers cost money. The
cheapest really good ones cost at least
So each and he needs two Of them. And
1t isn't every amateur who feels Ike
passing out a SO bill for apparatus
before he knows he is going to like It:
As we have said before, this standard
short wave regenrative hook up Is about
concerts. But It's also the hardest to
work. It will exhaust the patience Of
most amateurs and they will give up
in disgust, but, il they persevere and
learn the six or eight adjustments. they
will find they have an extremely sensi-
tive set and one by which they can tune
out virtually all interference.
In these little talks. we have taken
up all of the apparatus necessary except
the variometers. You can use regular
vario- coupler or else the one we built
Of two spiderweb coils mounted with
knob and thread to raise and lower
one from the other. ! prefer the spider
webs.
The variometer shown in the illustra-
tion Is the easiest one for the beginner
to build. 1t is not nearly so efficient
as the bought ones. but there isn't
knt,. IN n RI
most skilled in tool craft-who can wind
one like the factories turn out. If you
have the money to spare, by all means
buy two standard variometers- If not,
you can make two like the one illus.
trated and you'll get remarkably good
results on them. ,
I built my two out Of salt box and
n paper mailing tube. The salt box has
an outside diameter Of 35S inches. One
salt box is more than big enough for the
two yariometers. use pieces little
more than pa inches wide.
The mailing tube l use with this Is
2N inches outside diameter. ! use n
piece about 2la inches wide. That just
lets the piece of mailing tube turn all
the way around inside the salt box when
II is mounted. You need not use tubes
of these exact dimensions. The object
is to have them, so that the smaller will
turn inside the larger.
Most writer's advocate putting shaft
all the way through both tubes. find
It much better to use the method in the
I use two ordinary ma
chine screws (preferably brass. of
two inches long and any thick
ness that is handy. If they are passed
the holes in the tubes as the
pictures show, and the nuts screwed up
tight. they make an excellent shaft and
by this method. also act as separate
of the electric current.
Use No. "a or 26 cotton covered wire
for the windings. The two tubes are
wound in two sections, as you can see.
but these windings are continuous
that Is, you carry the wire right across
the open space when you have finished
the first section. and 60 on with the
second. The open space is simply to
give room for the shafts.
There are thirty turns of wire In each
of the four sections. This makes q total
IF sixty on the outer tube and sixty
IN the inner.
In starting. leave a good length of
loose end. This will later attach to
,ne Of the binding posts on the panel.
When the sixty turns on the outer coil
ire wound, fasten the last turn and