than is necessitated by the condition of the "A" battery or by
accidental short-circuit of the "B" battery through the filaments.
When the filaments are operated at too high a voltage
("
BATTERY SETTING
"
pointer advanced too far), the active material in
the filaments is rapidly driven off, and the useful life of the
Radiotrons and batteries is considerably shortened, without
proportional increase in signal strength or ease of operation. If it is
suspected that the filaments have been so damaged, it is
recommended that the Radiotrons be taken to the Authorized RCA
Dealer from whom the Radiola was purchased to be tested.
Often, improved operation may be obtained by interchanging
the UX-199 Radiotrons. This may be the case even when the
Radiotrons are new. The UX-120 Radiotron must always be used in
socket 6, at the left-hand end. The user can tell whether this
Radiotron is in operating condition by switching a telephone headset
or separate loudspeaker from the first stage jack H to the second
stage jack
M
,
Fig. 13. There should be a noticeable increase in signal
strength when connected to the second stage.
If there is not, the UX-
120 Radiotron should be replaced.
Of the five UX-199 Radiotrons, the one in socket
2
(second
from the right when facing the front of the set) is the most important,
and it is well to determine whether this Radiotron is working
properly. This may be done by touching a moistened finger to the
plates of the variable condenser on the right-hand side of the panel. A
sharp click should be heard in the loudspeaker.
If none is heard, try
interchanging this Radiotron with either the first, third, or fifth
Radiotron, applying the click test each time. Use for the fifth
Radiotron the one which gives the sharpest click in the loudspeaker.
A tendency to howl can usually be eliminated by:
(1) Interchanging the Radiotron in socket 4 (4th from the right)
with any of the remaining Radiotrons except those in sockets 2 and 6.
(2) Making a slight readjustment
of the “
BATTERY SETTING
"
pointer.
(3) Moving the loudspeaker to a different position with relation
to the Radiola.
It
is recommended not to place the loudspeaker on the
top of the cabinet.
Battery Connections.
These should be kept tight at all times.
A loose connection is likely to result in faulty operation, such as
noise in the loudspeaker or reduced signal strength, or make the
receiver inoperative. An occasional inspection of the battery
connections is desirable.
21
