Mullard Maintenance Manual
Preface and Copyright

PREFACE

In the past the service engineer has been rather overlooked when valve
and tube data have been published. Either he has had to be content with
very brief tables of 'characteristics' which often bear no relation to
practical conditions of operation, or he has been overwhelmed with 
complex information originally aimed at the equipment designer and which
appears to surround each type with a considerable number of mysterious
and seemingly unnecessary ]innitations. The 'Mullard Maintenance
Manual', having been prepared with the aim of providing the service
engineer with the information most useful to him in repairing and main-
taining radio and television receivers and amplifying equipment, is
intended to supplement the 'first-aid' information given in the Mullard
Wall chart (1954/5 edition). Whilst designers will undoubtedly find this
manual of assistance for general reference purposes they are recommended
to use the Mullard Technical Handbook, available on a subscription basis,
when designing their equipment. Details of the handbook service are
available upon request.
 
The manual is divided into two main sections - receiving valves and
television tubes. Each section commences with a comprehensive index
listing both Mullard and other manufacturers' types. This index gives the
recommended Mullard replacement where one is available and indicates
the page numbers in the data section of the Mullard types and information
on replacements. In addition to that on current types, information on
obsolete Mullard valves and tubes likely to be encountered when servicing
older receivers, is included in the data section.
 
In presenting the data, the conventional letter symbols have been used
in order to save space. These symbols are listed on a linen foldout at the
back of the manual.
 
Whilst every care has been taken in the compilation of the information
contained in this manual, particularly in the selection of suitable replace-
ments for other manufacturers' types, Mullard  Ltd. cannot accept
responsibility for the accuracy thereof. It should be noted particularly that
the fact that a Mullard direct replacement is given for another manu-
facturer's type does not imply that the reverse process will operate satis-
factorily in all cases. In preparing the list of 'Other Equivalents' in the
comprehensive index, only types listed by other manufacturers as equiva-
lents and indicated by them as available have been included. It is important
that wherever possible, when dealing with another manufacturer's types,
the manufacturer's catalogue should be referred to for operational details
or special limitations.
 
The information contained in this book is under constant review, parti-
cularly from the viewpoint of new and obsolete types. Further information
on Mullard valves and tubes can be obtained from the Technical Service
Department.


Prepared by:  Technical Service Department
              Mullard Limited

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