Enough of that cheap one-board crap..... this amp is MODULAR!

Modular design allows easy repair and modification, as well as ease of
construction and interchangeability between different amps. It also
allows seperation of functions both electronically and physically. The
modules include:

* Input module. Includes variable attenuator and dummy load which
provides adjustment of input power without 'tweaking' anything inside
the radio.

* Control module. Board that controls keying, bias & cooling fan.

* Sensor module. Board with circuits that take measurements from
various locations throughout the amp and sends them to a meter. Meter
function selection can be by rotory switch or by LCD display simply by
swapping the board (module). Meter functions may include:

- RF input power, Fwd
- RF input power, Ref (for matching amp input to radio output)
- Base current
- Emitter voltage, (RMS)
- Emitter voltage, (peak)
- Emitter current
- RF output power, Fwd (RMS)
- RF output power, Fwd (Peak)
- RF output power, Fwd (Peak & hold)
- RF output power, Ref
- AF input (Ext. mod. function, AM only, see below)
- DC supply voltage, amp
- DC supply voltage, radio
- DC supply current, amp
- DC supply current, radio

* Power Amplifier Module. The module will consist of the amplifier
circuit, heat sink and cooling fan, constructed inside an enclosed
sub-chassis designed for forced-air cooling. Flying in the face of
convention, the power amplifier circuit will -not- be mounted on a PC
board. Instead, the components will be chassis-wired with heavy-guage
copper, except for the transistors which will be wired with strips of
copper sheet having rounded edges and corners. This allows easy repair
and modification, as well as more secure and robust connections.
Circuit will be an ultra-linear, broadband, AB push-pull design
(details at a later date).

* Output module. Includes matching network and output connector, the
type of which depends on the desired output method: balanced or
unbalanced. The reason is that an unbalanced output is fine for mobile
amps where the amp is mounted to an adequate RF ground, but that is
rarely the case with base amps. So an option is provided for balanced
output; the line can then be run to a point where a good RF ground can
be found (e.g, a ground rod right outside the window) where it is
coupled to a coax with a balun, or simply run balanced right to the
antenna. The user now has these choices and they are built right into
the amp!

* Power supply module (optional). Power transistors that are designed
for higher voltage are more linear and -much- more reliable than those
designed to operate on 12-14 volts. This switching power supply bumps
up the voltage to 28 or 50 VDC and allows the use of such transistors.


Additional features:

* An external modulation function can be included, allowing the amp to
function as a Class C modulator. Audio input is via a terminal strip
on the back and fed from a common 8-ohm audio amplifier. The base bias
is then adjusted (with a screwdriver through a hole in front panel) to
Class C operation for higher efficiency. This works only in AM mode.
There is no provision for audio filtering, so hi-fi (wideband) AM is
possible if desired.

* Connections for remote operation:
- Key ground
- Key on ground
- Key on high (=+5VDC)
- Key function select 1 (amp in/out)
- Key function select 2 (key auto/manual)
- Key function select 3 (AM/SSB)


I am open to any comments or suggestions, provided they are limited in
scope to the design concept and desired features.