U.S. patent number RE43,820 [Application Number 12/454,700] was granted by the patent office on 2012-11-20 for rf circuit module and chassis including amplifier.
This patent grant is currently assigned to ATX Networks Corp.. Invention is credited to Glen Backes, Zakhary Bluband, Todd Charles Ortberg.
United States Patent |
RE43,820 |
Ortberg , et al. |
November 20, 2012 |
RF circuit module and chassis including amplifier
Abstract
An amplifier module for radio frequency signal circuits includes
an electrically conductive housing. Two coax connectors are
electrically linked to an amplifier circuit contained within the
module. A separate transformer is external to the module. Both the
module and the external transformer are mountable to a chassis
frame. Other modules are usable in the system in addition to the
amplifier module. The transformer can be wall mounted to the
chassis frame, or the transformer can be internal to a module which
also mounts to the chassis frame.
Inventors: |
Ortberg; Todd Charles
(Chanhassen, MN), Bluband; Zakhary (Minnetonka, MN),
Backes; Glen (Maple Grove, MN) |
Assignee: |
ATX Networks Corp. (Ajax,
Ontario, CA)
|
Family
ID: |
25533800 |
Appl.
No.: |
12/454,700 |
Filed: |
May 20, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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09977626 |
Oct 12, 2001 |
Re. 40750 |
|
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Reissue of: |
08988047 |
Dec 10, 1997 |
5966648 |
Oct 12, 1999 |
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Current U.S.
Class: |
455/347; 361/752;
455/341; 455/349; 455/90.3 |
Current CPC
Class: |
H05K
7/1425 (20130101); H04B 1/08 (20130101) |
Current International
Class: |
H04B
1/08 (20060101) |
Field of
Search: |
;455/90.3,341,347-349,575.1 ;361/733,752,785,796 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Scientific-Atlanta, Inc. document, "Handbook for Headend Products
Training School," pp. front cover, 3-1, 3-9, 4-1, 4-5, 7-4,7-5, 7-6
(8 pages) (Sep. 1983). cited by other .
Scientific-Atlanta Product Model No. 6350, 16 photographs (16
pages). cited by other .
"Headend Combining/Splitting Network," Cox Communications, undated,
16 pages. cited by other .
Crutchfield Catalog, Summer 1994, p. 60. cited by other .
Text and drawings of U.S. Appl. No. 08/761,525, filed Dec. 6, 1996.
cited by other .
Text and drawings of U.S. Appl. No. 08/900,187, filed Jul. 25,
1997. cited by other .
Text and drawings of U.S. Appl. No. 08/761,776, filed Dec. 6, 1996.
cited by other .
Text and drawings of U.S. Appl. No. 08/761,723, filed Dec. 6, 1996.
cited by other .
ADC Telecommunications, Inc. Catalog, "Video Signal Distribution
Products," 2 front cover pages, pp. 1-47, and back cover page,
dated Oct. 1996. cited by other .
ADC Telecommunications, Inc. catalog "ADC's RF Worx.TM. RF
Distribution and Management Products", 12 pages, dated Dec. 1996.
cited by other .
ADC Telecommunications Inc. document, RF Worx Passive
Splitter/Combiner and Directional Coupler User Manual, 23 pages,
dated 1997. cited by other .
Text and drawings of U.S. Appl. No. 08/762,519, filed Dec. 6, 1996.
cited by other.
|
Primary Examiner: Nguyen; Simon
Attorney, Agent or Firm: Brinks Hofer Gilson & Lione
Parent Case Text
.Iadd.Notice: More than one reissue application has been filed for
the reissue of U.S. Pat. No. 5,966,648. The reissue patent
applications include the present reissue application and reissue
application Ser. No. 09/977,626, filed Oct. 12, 2001. The present
reissue application is a continuation of reissue patent application
Ser. No. 09/977,626 filed Oct. 12, 2001 now U.S. Pat. No. Re.
40,750..Iaddend.
Claims
What is claimed is:
.[.1. A chassis frame and module combination comprising: a) an
amplifier module having: 1) a housing of electrically conductive
material defining an enclosed interior; said housing having a front
face and an opposite rear face separated by opposite sidewalls and
opposite end walls, with each of said faces and sidewalls being of
predetermined dimension and with said sidewalls being parallel to
one another; each of said end walls having a projecting flange
extending in a common plane generally parallel to said sidewalls
and with said common plane offset from a central longitudinal axis
of said housing; said front face including end portions extending
beyond each of said end walls; 2) two coax connectors secured to
said rear face with an outer shield of said coax connectors
electrically coupled to said housing; 3) a circuit board contained
within said interior and positioned generally parallel to and
spaced between said sidewalls; said circuit board having a
component side opposing a first of said sidewalls and a ground side
opposing a second of said sidewalls, said ground side including a
layer of electrically conductive material electrically connected to
said housing; a plurality of connection locations on said circuit
board, each of said connection locations including a ground
connection for connecting ground shields of coax cables to said
layer of electrically conductive material; said component side of
said circuit board including a circuit component interconnected
with said connection locations through a circuit path; said circuit
component including an amplifier circuit selected to amplify a
radio frequency signal supplied to one of said coax connectors and
to provide an amplified radio frequency signal to the other of said
coax connectors; said coax connectors connected to said connection
locations, each of said outer shields of said coax connectors
connected to said ground connections of said connection locations;
4) A power supply port located on said rear face; said power supply
port interconnected to said amplifier circuit through a circuit
path of said circuit board; b) a chassis frame including a pair of
spaced apart walls, said walls spaced apart by a distance
substantially equal to a distance between said end walls of said
module; each of said walls including a groove, each groove sized to
slideably receive one of said projecting flanges; c) a lock member
for locking at least one of said end portions to said chassis
frame; d) a transformer separate from said amplifier module, said
transformer mounted to said chassis frame, said transformer
electrically coupled to said power supply port of said amplifier
module for powering said amplifier circuit..].
.[.2. The chassis frame and module of claim 1, further comprising a
first test coax connector secured to said front face; said first
test coax connector electrically coupled to a circuit path of said
circuit board to monitor the radio frequency signal supplied to
said amplifier circuit..].
.[.3. The chassis frame and module of claim 2, further comprising a
second test coax connector secured to said front face; said second
test coax connector electrically coupled to a circuit path of said
circuit board to monitor the radio frequency signal from said
amplifier circuit..].
.[.4. The chassis frame and module of claim 1, further comprising a
test coax connector secured to said front face; said test coax
connector electrically coupled to a circuit path of said circuit
board to monitor the radio frequency signal from said amplifier
circuit..].
.[.5. The chassis frame and module of claim 1, wherein said circuit
component of said amplifier module further includes a tilt
circuit..].
.[.6. The chassis frame and module of claim 1, wherein said circuit
component of said amplifier module further includes a power on
indicator, said power on indicator including an LED positioned on
said front face..].
.[.7. The chassis frame and module of claim 1, wherein said circuit
component of said amplifier module further includes a gain
potentiometer, and said front face including an adjustment access
point to adjust said gain potentiometer..].
.[.8. The chassis frame and module of claim 1, further comprising a
transformer module for holding the transformer, the transformer
module having a housing with a front face, a rear face, opposite
sidewalls and end walls, each of the end walls having a projecting
flange, each projecting flange received in one of the pairs of
aligned grooves of the walls of the chassis frame..].
.[.9. The chassis frame and module of claim 1, wherein the pair of
spaced apart walls is a first pair, and wherein the chassis frame
includes a second pair of spaced apart walls spaced apart a
distance substantially equal to the first pair, each wall of the
second pair including a flange receiving groove for receiving an
additional radio frequency module configured and arranged with a
housing like the housing of the amplifier module..].
.Iadd.10. A chassis frame and module combination comprising: a) a
plurality of modules including: 1) an amplifier module having: A) a
housing defining an enclosed interior; B) two coax connectors
accessible from a back of the housing with an outer shield of said
coax connectors electrically coupled to said housing; C) circuitry
contained within said housing; said circuitry including an
amplifier circuit selected to amplify a radio frequency signal
supplied to one of said coax connectors and to provide an amplified
radio frequency signal to the other of said connectors; D) a power
supply contact operatively coupled to said amplifier circuit; 2) a
power downconverter module having a power downconverter
electrically coupled to said power supply contact of said amplifier
module for powering said amplifier circuit; b) a chassis frame
sized to receive said amplifier and power downconverter modules,
wherein said power downconverter module is selectively receivable
in a plurality of positions in said chassis..Iaddend.
.Iadd.11. The chassis frame and module combination of claim 10,
wherein said coax connectors are secured to the back of the
housing..Iaddend.
.Iadd.12. The chassis frame and module combination of claim 10,
wherein the back of the housing is an electrically conductive
material, and wherein the outer shields of coax connectors are in
direct physical contact with the back of the housing..Iaddend.
.Iadd.13. The chassis frame and module combination of claim 10,
further comprising a printed circuit board positioned within the
housing, the amplifier circuit being contained on the printed
circuit board..Iaddend.
.Iadd.14. The chassis frame and module combination of claim 13,
wherein at least a portion of each of the coax connectors is
directly connected to the printed circuit board..Iaddend.
.Iadd.15. The chassis frame and module combination of claim 13, the
housing further including a front and opposing sidewalls separating
the front and the back of the housing, wherein the printed circuit
board is positioned generally parallel to and between the
sidewalls..Iaddend.
.Iadd.16. The chassis frame and module combination of claim 10,
wherein said circuitry of said amplifier module further includes a
power on indicator, said power on indicator including an LED
positioned on a front of said amplifier module..Iaddend.
.Iadd.17. The chassis frame and module combination of claim 10,
wherein the coax connectors are positioned adjacent the back of the
module and electrically connected with the circuitry..Iaddend.
.Iadd.18. A chassis frame and module combination comprising: a) a
plurality of modules including: 1) an amplifier module having: A) a
housing defining an enclosed interior; B) at least one RF signal
input and at least one RF signal output, the RF signal input and
output accessible from a back of the module; C) circuitry contained
within said housing; said circuitry including an amplifier circuit
selected to amplify a radio frequency signal supplied to the at
least one RF signal input and to provide an amplified radio
frequency signal to the at least one RF signal output; D) a power
supply input operatively coupled to said amplifier circuit; 2) a
power downconverter module having a power downconverter
electrically coupled to said power supply input of said amplifier
module for powering said amplifier circuit; b) a chassis frame
sized to receive said amplifier and power downconverter modules,
wherein said power downconverter module is selectively receivable
in a plurality of positions in said chassis..Iaddend.
.Iadd.19. The chassis frame and module combination of claim 18,
wherein the RF signal output and the RF signal input each include a
coax connector positioned adjacent the back of the module and
electrically connected with the circuitry..Iaddend.
.Iadd.20. The chassis frame and module combination of claim 19,
wherein said coax connectors are secured to the back of the
housing..Iaddend.
.Iadd.21. The chassis frame and module combination of claim 20,
wherein the coax connectors include outer shields, and wherein the
back of the housing is an electrically conductive material, the
outer shields of the coax connectors being in direct physical
contact with the back of the housing..Iaddend.
.Iadd.22. The chassis frame and module combination of claim 18,
further comprising a printed circuit board positioned within the
housing, the amplifier circuit being contained on the printed
circuit board..Iaddend.
.Iadd.23. The chassis frame and module combination of claim 22, the
housing further including a front and opposing sidewalls separating
the front and the back of the housing, wherein the printed circuit
board is positioned generally parallel to and between the
sidewalls..Iaddend.
.Iadd.24. The chassis frame and module combination of claim 18,
wherein said circuitry of said amplifier module further includes a
power on indicator, said power on indicator including an LED
positioned on a front of said amplifier module..Iaddend.
Description
I. BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to circuits for broad-band RF (radio
frequency) systems. More particularly, this invention pertains to
modular RF circuit components.
2. Description of the Prior Art
In the telecommunications industry and more particularly in the
video transmission industry, broad-band radio frequency (RF)
signals (i.e., 5 MHz to 1 GHz) are carried over coax conductors
from a headend to consumers. At the headend of the system, numerous
signals are manipulated to achieve a wide variety of functions and
objectives. For example, signals carried on the coax cables may
need to be amplified, such as for return path applications. Also,
the signals from numerous coax cables may be combined onto a single
coax conductor. Similarly, a signal on a main coax conductor may be
divided into a plurality of signals carried on branch coax
conductors. Additionally, signals may be added or removed from a
main conductor through directional couplers or the like.
In addition to combining, splitting, diverting or adding signals,
the headend will also include apparatus for modifying signals. For
example, in order to adequately tune the system, it may be
desirable to provide attenuators or the like to attenuate a signal
to a desired level. Further, as a broadband RF signal is carried
over a length of cable, the high frequency range of the signal may
be attenuated more than a low frequency range of the signal. As a
result, equalizers are utilized to modify the signal to have a
level intensity throughout its frequency range.
Throughout the system, performance characteristics are critical.
For example, a common performance criteria is to maintain the
flatness of a signal. Flatness refers to maintaining a level
intensity of a signal throughout its frequency range. For example,
if the signal is attenuated by 2 dB at 1 Ghz, then it is desirable
that the signal be attenuated at 2 dB at the 5 Mhz frequency.
Further, the system needs to be tuned for impedance matching.
Prior art headends include a wide variety of devices to accommodate
and accomplish the functions described above. It is desirable to
provide an apparatus to accommodate the various functions required
at the headend through a modular construction to permit ease of
maintenance and cable management in a headend. Such a device must
accommodate the performance characteristics of the headend while
permitting the modular construction to enhance the cable management
and organization of a headend.
II. SUMMARY OF THE INVENTION
According to a preferred embodiment of the present invention, a
chassis and module combination is provided for amplification of a
radio frequency signal. The amplifier module comprises a housing of
electrically conductive material defining an enclosed interior. The
housing has a front face, and an opposite rear face separated by
opposite side-walls and opposite end walls. Each of the faces and
side-walls has a predetermined dimension with the sidewalls being
parallel to one another. Each of the end walls has a projecting
flange extending in a common plane generally parallel to the
sidewalls and with the common plane offset from a central
longitudinal axis of the housing. The front face includes end
portions extending beyond each of the end walls. Two coax
connectors are secured to the rear face for carrying the radio
frequency signal to and from the module. A circuit board is
contained within an interior of the housing and is positioned
generally parallel to and spaced between the sidewalls. The circuit
board includes an amplifier circuit selected to amplify a radio
frequency signal supplied to one of the coax connectors, and to
provide the amplified radio frequency signal to the other of the
coax connectors. A power supply port is also located on the rear
face of the module. The power supply port is interconnected to the
amplifier circuit within the module through a circuit path of the
circuit board. A chassis frame for holding the amplifier module
comprises a pair of spaced apart walls which are spaced apart by a
distance substantially equal to a distance between the end walls of
the module. Each of the walls of the chassis frame includes a
plurality of aligned grooves sized to slideably receive the
projecting flanges of the module. The grooves are spaced apart
along the walls to allow for a predetermined number of similarly
configured additional radio frequency modules to be received by the
chassis frame. The other modules can have the same or other
functions. A lock member locks at least one of the end portions of
the amplifier module to the chassis frame. A separate transformer
is mounted to the chassis frame wherein the transformer is
electrically coupled to the power supply port of the amplifier
module for powering the amplifier circuit of the amplifier module.
The separate transformer can be positioned in a module mountable to
the chassis frame in a similar manner as the amplifier module, as
desired.
In the preferred embodiment, first and second test coax connectors
are secured to the front face of the amplifier module to provide
two access monitor test points for the amplifier circuit, one test
point to allow for monitoring of the radio frequency signal
supplied to the amplifier circuit, the other to allow for
monitoring of the radio frequency signal from the amplifier
circuit. Further preferred features include a tilt circuit, a power
on indicator, and a gain potentiometer for the amplifier
module.
III. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front perspective view of two amplifier modules,
vertically mounted, and a chassis frame according to one embodiment
of the present invention;
FIG. 2 is a rear perspective view of the amplifier modules and
chassis frame shown in FIG. 1, and showing two chassis frame
mounted transformers coupled to the amplifier modules;
FIG. 3 is a front perspective view of one of the amplifier
modules;
FIG. 4 is a rear perspective view of the amplifier module of FIG.
3;
FIG. 5 is an exploded front perspective view of the amplifier
module of FIG. 3;
FIG. 6 is an exploded rear perspective view of the amplifier module
of FIG. 3;
FIG. 7 is an enlarged rear perspective view of a portion of the
amplifier module, including portions of the housing broken away for
viewing internal components;
FIG. 8 is an electrical schematic of the amplifier module and
external transformer;
FIG. 9 is a front perspective alternative chassis frame including a
horizontal mounting of the modules, and where one of the modules is
configured and arranged to house a transformer for an amplifier
module;
FIG. 10 is a rear perspective of the embodiment of FIG. 9;
FIG. 11 is a front view of the embodiment of FIG. 9; and
FIG. 12 is a rear view of the embodiment of FIG. 9.
IV. DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the several drawing figures in which identical
elements are numbered identically throughout, a description of the
preferred embodiments of the present invention will now be
provided.
With initial reference to FIGS. 1 and 2, an amplifier module 10
according to the present invention will be described for use with a
chassis frame 12. In FIGS. 1 and 2, two modules 10 are shown. Each
module 10 receives a radio frequency signal and provides an
amplified radio frequency signal as an output. Module 10 is
constructed generally as a modular unit usable with other radio
frequency modules and chassis frames as described in U.S. patent
application Ser. No. 08/761,525, filed Dec. 6, 1996, the disclosure
of which is incorporated by reference. The various modules of U.S.
application Ser. No. 08/761,525 include splitter/combiner modules,
equalizer modules, and directional coupler modules. These modules
and other modules which perform various functions on the radio
frequency signals required at the headend are usable with the
amplifier module 10 of the present invention.
The module 10 includes a housing 13 having a front face 14, and a
rear face 16. The front face 14 and the rear face 16 are separated
by opposing sidewalls 18, 20 and opposite end walls 22, 24. The
housing 13 is formed of electrically conductive material.
Preferably, the material is nickel-plated aluminum. Various vent
holes 27 are provided to allow air to enter and exit housing
13.
Sidewall 18 and end walls 22, 24 are integrally formed as a box
configuration with walls 22,24 having inwardly protruding
peripheral ledges 26. Rear wall 16 is secured to walls 18, 22, 24
by Phillips head screws 28 in aligned holes 30 and threaded holes
32. Front face 14 also has a ledge 26a. The sidewall 20 is fastened
to the ledges 26, 26a and rear wall 16 by a plurality of screws 28
received in aligned holes 30 and threaded holes 32.
Sidewall 20 is sized to have a length greater than the longitudinal
dimension between walls 22, 24 such that ends 20a, 20b extend
beyond end walls 22, 24 as flanges for mounting to chassis frame
12. The front face 14 includes extending end portions 14a, 14b
which extend beyond end walls 22, 24. Apertures 14c, 14d receive
fasteners 29 to lock each module 10 to chassis frame 12.
Two coax connectors 40, 41 are secured to the rear face 16. Each of
coax connectors 40, 41 is a 75 ohm F-type connector press fit into
rear face 16 and includes a central conductor 42 surrounded by a
grounded shield 43. The grounded shields 43 of the coax connectors
40, 41 are in direct physical and electrical contact with the
electrically conductive material of the rear face 16.
Contained within the interior of the housing 12 is a printed
circuit board 44. The printed circuit board 44 is supported on
posts 45 by screws 46. The posts 45 are electrically conductive and
connected to wall 18. Printed circuit board 44 includes a component
side 44a and a ground side 44b. The ground side 44b opposes the
wall 18 and the component side 44a opposes the wall 20. The printed
circuit board 44 is maintained in parallel, spaced relation between
the walls 18, 20 by posts 42.
A layer 44c (FIG. 7) of electrically conductive material (such as a
sheet layer of copper) is provided on the exterior surface of
surface 44b. Two connection locations 48a, 48b are provided on the
ground side 44b of the printed circuit board 44. Each of the
connection locations 48a, 48b includes a ground connection for
connecting the ground shield at the tabs 43a of the coax connectors
40, 41 to the conductive layer 44c, such as by soldering. Central
conductors 42 of each connector 40, 41 are also soldered to printed
circuit board 44 to component side 44a at connection locations 48c,
48d.
A plurality of circuit components are disposed on the component
side 44a of the printed circuit board 44 (leaded through hole or
surface mount). In the embodiment shown, an amplifier circuit 50
(see FIG. 8) is included in the circuit components. An amplifier
module 52 is screwed to the rear face 16 at screw holes 52b so as
to form a heat sink. Pins 53 of the amplifier module 52 plug into
sockets on the printed circuit board 44 at connection location 49a.
Two cable assemblies 56, 58 run from the printed circuit board 44
at connection locations 56a, 58a to the front face 14. Front face
14 includes two 75 ohm F-type coax cable connectors 59, 60 mounted
to front face 14, such as with a threaded nut, to form termination
points of cable assemblies 56, 58 which provide front access
monitor test points for monitoring the radio frequency signal
before and after amplification. An indicator circuit 61 mounted to
printed circuit board 44, and including an LED 62 on the front face
14 indicates power on. A gain potentiometer 70 with an access
adjustment point 72 is also on the front face 14 and can be
adjusted (from 0 to 20 dB in the example shown) with a flat head
screwdriver. A power supply port 90 is mounted adjacent to rear
face 16. Pins 91 of port 90 connect to printed circuit board 44 at
connection location 49b. A transformer 100 connected via cord 101
to an external power source converts 120 volts of alternating
current to 24 volts of alternating current. Transformer 100
supplies the 24 volts of alternating current to the power supply
port 90 through wires 120. Alternatively, the power input to the
amplifier module 10 can be minus 48 volts of direct current to the
transformer 100, whereby a suitably configured transformer 100
would convert it to 24 volts of direct current to power the
amplifier circuit 50.
A full-wave bridge rectifier circuit 120 is provided as part of the
power supply circuit for amplifier circuit 50 of amplifier module
10. A heat sink 122 is mounted to printed circuit board 44 at
connection location 49c to provide a heat sink for voltage
regulator 124 of rectifier circuit 120. A tilt circuit 130 is
provided to compensate for slope in the magnetic and connector
features. Such a circuit flattens out the frequency response of the
amplifier circuit 50. The cable assemblies 56, 58 including the
monitor coax connectors 59, 60 draw a 20 dB signal due to the 17.5
dB couplers 140 and the 2.5 dB pads 150.
Chassis frame 12 includes spaced apart walls 202, 204 spaced apart
by a distance substantially equal to a distance between the end
walls 22, 24 of the module 10. Each of the walls 202, 204 includes
a plurality of vertically aligned grooves 210. The grooves 210 are
sized to slideably receive the projecting flanges 20a, 20b of the
module 10 such that a module may be slideably inserted into the
chassis frame 12 with the modules 10 vertically positioned. In the
embodiment shown, there are multiple pairs of vertically aligned
grooves 210 such that additional modules may be inserted into the
chassis frame 12. Since the flanges 20a, 20b of the modules 10 are
offset from a longitudinal plane of the module 10, the grooves 210
are offset from module receiving spaces so that the entire open
space between the side-walls of the chassis frame may be filled
with modules. Also, the grooves 210 are spaced apart a distance
selected such that as modules as slideably inserted into the frame,
adjacent modules are positioned with a small spacing between
opposing sidewalls of adjacent modules. The locking fasteners 29
are provided through the projecting end portions 14a, 14b of the
front faces 14 of the module 10 for receipt in corresponding
threaded locking holes 216 provided on walls 202, 204 of chassis
frame 12.
Transformer 100 is shown separate from amplifier module 10.
Transformer 100 is vertically mounted to a vertical side piece 220
of chassis frame 12. Chassis frame extension 220a (not illustrated
in FIG. 2) could also be a mounting location for transformer
100.
From time to time, a customer or purchaser of the module 10 may
desire to hold the modules and other radio frequency modules in a
horizontal alignment rather than the vertical alignment of FIGS. 1
and 2. An alternative chassis frame 12' is shown in FIGS. 9-12 for
holding the modules 10 in a horizontal alignment. Two pairs of
walls 202', 204' are provided, and each wall has the flange
receiving grooves 210'.
Instead of transformer 100 being a wall mounted unit separate from
module 10, the transformer can also be internal to its own module
10' also separate from amplifier module 10 which is received by one
of the chassis frames 12, 12'. FIGS. 9-12 illustrate transformer
module 10' having an internal transformer disposed within housing
13'. Power supply port 240 links an external power source (i.e.,
120 volts a.c.,-48 volts d.c.) over wires 242 to transformer module
10'. The internal transformer outputs the proper voltage through
port 240 over wires 244 to the power supply port 90 of amplifier
module 10. Power on indicator 260 provides visual output whether
transformer module 10' is supplied with external power. Also,
transformer module 10' can be two or more modules 10 in width
between walls 18' and 20', as desired, to provide more internal
space for components.
Having described the present invention in a preferred embodiment,
modifications and equivalents may occur to one skilled in the art.
It is intended that such modifications and equivalents shall be
included within the scope of the claims which are appended
hereto.
* * * * *