Belt Valley times. [volume] (Armington, Mont.) 1894-1977, 1926-06-17

at the United States Bureau
When a radio receiver fails TO give
Its customary volume the "B' bat
teries are almost invariably blamed.
II Is true that they are sometimes
the cause Of this trouble but II is aq-
visable to measure their voltage be-
fore arriving at this conclusion. A
good make OF 'sB" battery OF adequate
size should last, even with q receiver
consuming heavy "B" battery current
for at least six months and If it is a
moderately economical receiver, from
nine to twelve months, provided 1t is
given the average use OF about two
hours per day. Failure to give such
life is an indication, either that It is a
battery Of inferior make, or Of mad
eQuate capacity for the set used or
that there is defect In the receiver.
Causes Of Short Battery Life.
Briefly, the factors most frequent
" causing short @Bn battery life are;
/. Audio-frequency amplifer not
equipped with &C" battery.
2. &C" battery exhausted.
8. Excessive plate voltage.
4. Tubes draw excessive current be-
cause Of accidental displacement Of
grid and plate.
s. "B" battery OF insufficient ca
pacity for the drain placed upon 1t.
This last cause Is frequently over
looked because the first cost Of large
batteries is somewhat more than that
OF small ones But 1t Is indeed a
wasteful practice to use battery Of
inadequate capacity; this is apparent
II the cost Is figured In cent per hour
Of use, rather than In first cost. On
the face OF II, certainly 1t seems more
expensive TO pay about IS per cent
more for a heavy duty ''B" battery.
but the economy is apparent when the
heavy duty lasts twice as long in
service as the large" size battery.
The savings are even greater when
heavy duty ''B" batteries are sub
stituted for the small portable size
batteries which are sometimes err
roneously used for home receivers.
There have been cases when "B'
battery maintenance cost has been
reduced from IL cents an hour to
cents an hour by using a heavy duty
or extra large "B" battery In prefer
ence to one of the portable sizes.
II frequently happens that receiy-
ing set owners replace their ''B" bat
teriee when volume falls. The slightly
increased volume which new 'B" bat
teriea give may lead to the conclusion
that an exhausted "B" battery was
the cause Of the reduced volume. A
'B" battery v0ltmeter, however,
might show only a normal fall In
voltage which would not account for
the reduction In volume.
In such cases It Is advisable to
Inspect the antenna connections for
q broken or corroded lead-in, loose
ground connection, worn out ''C' bat
terry or lost magnetization Of loud
speaker unit. Still another cause Of
reduced volume is the loss Of active
material on the tube filaments. Quot
ing from the Technical News Bulletin.
issued by the national bureau Of
standards:
Tubes Loss ssnsltlvIty.
~Electron tubes In radio receiving
sets eventually lose their sensitivity. |
This sometimes progresses to the point |
where the receiving set operates very
poorly or not at all, even though the
tube nlament Is not burned out. Tho |
user OF the set frequently confuses
this condition with that due to an
exhausted .'B" battery. II the tubes
are Of the thoriated tungsten (X-L) .
type. they ran usually be re-
iuvenated to serve as well as new
tubes In the receiving set"
A simple process OF rejuvenation.
which can be performed at home, con-
slstn in dlseonnecting the sB" battery |
rom the set and burning the fla-
merits az full brflliance for a half hour.
Usually this restores the flaments to
eull activity.
The two major causes Of reduced
polume are exhausted ~B" batteries
and woFn-out tube HIamentR II la
,aay 10 determine which is Fesponsi-
bic fer the losa Of volume. A good. re
liable voltneter win indicate the con-
alton Of the ~ batteries n sach
a6-volt -" battery registers "a volts
or more, the cause Of reduced vol
nme lies elsewhere. probably with the
lnbea Lacking reliable voltEneter 20
test 'B~ batteries. a good plan IL 70