Belt Valley times. [volume] (Armington, Mont.) 1894-1977, 1926-03-11
BY EDWARD sPIEoLER,


| WAlhVul Auoo VI uOlttcfs lut writer De
lieves II is difficult to ind enc mori
desirable than a straight five-tube
three-dial tuned radlO-frequency Sc
constructed with efficient condenser,
and tuning coils and equipped with
standard accessories. The sensitive
ness. selectivity and volume OF ar
outfit of this type can be practically
guaranteed in advance and the build
er can be assured that he is moi
spending his money on some ones
notion OF freakIshly different" re.
celver Of undetermined worth. When
he has finished the wiring and con-
nected the batteries he will hear
broadcastlng. and hear It well.
The writer recently completed such
a receiver. Incorporating In It the
acceptable innovation OF few new
tuning inductances, and enjoyed an
instant satisfaction from It that was
unusual. He had previously made
number Of popularity exploited radio
frequency sets OF different design, and
had spent whole evenings OF patient
adjustment on each In an effort to
obtain good results. This orthodox,
nnpretentious outfit, Boosting moth
Ing more radical than some straight
line frequency eondensers and some
different r. F. coils. produced such
Immediate results IN the form OF many
and loud stations that he thinks PEG,
Pile who want fool-proof receivers
should be told about 1t.
Parts Required.
The average constructor Will have
no difficulty In assembling the set with
the aid Of ordinary hand tools. The
parts required are a panel Z by "a
inches. OF any good Insulating ma
terial; half-inch thick wood base
board Of the same dimensions, three
Gen-wIn Lemnis coils, three .OOO85
MID. stralght-line frequency condens-
err, three dIais to At same, one six.
and one thirty-obm rheOstat, one
double and one single circuit telephone
jack FIVE standard tube sockets, grid
condenser and leak. two audlo-fre-
quency transformers, one battery
switch, one binding post strip and
the usual busbar and other lncidentals.
The set Is most conveniently as
sembled In two units, the panel and
the dashboard.
The sockets for the Il. r. tubes &C.
cupy the space between the variable
and a little TO the rear OF
them. The detector socket Is up In
the extreme upper right corner OF the
Dashboard. and is followed by the A.
F. transformers and tubes winding
along the back edge OF the board. The
second A. F. tube is I'm the upper left
section, its up" post going convenient
y to the telephone Jack In the lower
eft corner Of the panel. Similarly, the
right-hand Jack connects to the adj
accent detector socket.
This U-shaped layout keeps all the
very short and In their
ogicaI order.
About 30 per cent Of the wiring I'm
yolved in the construction OF this
leceiver can and should BE- done on
he Dashboard instruments before the
laneI is screwed into position. The
constructor is advised against as
embling the parts first and wiring
fterward, as the presence Of the pro-
ruding variable condensers will make /
be installation of many OF the wires ,
Exceedingly difficult ,
No binding posts are provided for :
be &C" battery. as this unit Is most
asfIy connected by means OF short | !,
myths Of flexible cord. The other :
artery connections are standard and !
re easily followed =
The Wiring. :
The wiring OF the r. r. and A. r.
ages IL more or less orthodox I'm :
lture. The three variable c0ndensers 1
e connected directly across the re-
,ective secondaries Of the Lemnls
'ils, with stationary plates going to
e grids Of the tubes and rotary :, !,
ates to the flament circuit. -
The feature OF this receiver, outside "
It's general effectiveness. IL the type p
radl0-frequency tuning units en- ~
Dyed Each one consists OF a Is ~
m primary and a 103-turn second %
- NtaC Watr DCAhh WOHbu dtIOfuiuH -
the lemniscats principle. This form ~
mines the electromagnetic field and &c
utraIlzes the tendency toward oscIl- ~
ion. The extraordinary length Of ~
, lemnlscate curve reduces the re- .A'
lance otherwise encountered in l.o
all diameter coils. pia
The wire used is No. % enameIed. va
n turn-to-turn capacity being -
oided by system Of spaced wind
!. Over al, a coil Is inst three
hes long and two and three
lrters across the loops; the small ter
meter Of the latter Is one inch. der
Ingenious experlmenter can VIII
Oily rig up a winding Jig made OF the
} short curtain pole sections naised nee
end OF a board and produce de- Of
ibIe coils. ven
he directions which the magnetic II 1