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.

"Frank Gilliland" wrote in message
...

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

Yes, what are you going on about? Are you talking about an amp that exists,
something you would like to see or something you want. You have just quoted
a load of nonsense.

On Tue, 19 Sep 2006 22:51:37 +0100, "malc" wrote in
:


"Frank Gilliland" wrote in message
.. .

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

Yes, what are you going on about? Are you talking about an amp that exists,
something you would like to see or something you want. You have just quoted
a load of nonsense.


This is a project to design and build an amp. Once the preliminary
design is complete it will be built, tested and refined. All final
design parameters will be released for public use. Feel free to
contribute.

Modular design has its benefits but it also has at least two
disadvantages.

1. Initial cost

2. Problematic connections/connectors between high current modules.

On Tue, 19 Sep 2006 18:56:34 -0400, wrote in
:

Modular design has its benefits but it also has at least two
disadvantages.

1. Initial cost


Good point. And the final product costs will also be somewhat higher
than single-board designs. But that extra expense may be offset when
considering the product's usable lifetime. IOW, single-board designs
are so cheap they are frequently considered to be 'disposable', while
the sevicable lifetime of modular designs are limited only by the
availability of parts. I'll have to see if there's enough info
available to do an objective cost-benefit analysis.


2. Problematic connections/connectors between high current modules.


Connectors are a necessity, but they are only problematic if you make
them problematic. And since I haven't specified what connectors will
be used and where, don't you think you are jumping the gun a bit?

Frank Gilliland wrote:
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.


No PCB!... transistors wired with strips of copper... sounds like a
Davemade... better known as a "prototype"... LOL

www.telstar-electronics.com

On 19 Sep 2006 16:54:16 -0700, "Telstar Electronics"
wrote in
om:

Frank Gilliland wrote:
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.


No PCB!... transistors wired with strips of copper... sounds like a
Davemade... better known as a "prototype"... LOL


No PCB = no cracked traces, copper seperation, no burnt boards, better
heat dissipation, more efficient conductors, etc, etc. Let's face it:
replace the power transistors more than twice on a PCB and your board
(and therfore your amp) is garbage. Not only that, but it also allows
the flexibility to use transistors of different physical sizes and
styles; i.e, the amp can be upgraded or retrofit as desired.

Frank Gilliland wrote:
No PCB = no cracked traces, copper seperation, no burnt boards, better
heat dissipation, more efficient conductors, etc, etc. Let's face it:
replace the power transistors more than twice on a PCB and your board
(and therfore your amp) is garbage. Not only that, but it also allows
the flexibility to use transistors of different physical sizes and
styles; i.e, the amp can be upgraded or retrofit as desired.

You're losin' it... no PCB at RF frequencies means wires and
uncontrolled inductances / resonances all over the place causing
instabilities... resulting in oscillations. Why don't you think any
commercial amps are built your way.
Great idea Frank... LOL... you're truly a great engineer!

www.telstar-electronics.com

On 20 Sep 2006 02:53:13 -0700, "Telstar Electronics"
wrote in
om:


Frank Gilliland wrote:
No PCB = no cracked traces, copper seperation, no burnt boards, better
heat dissipation, more efficient conductors, etc, etc. Let's face it:
replace the power transistors more than twice on a PCB and your board
(and therfore your amp) is garbage. Not only that, but it also allows
the flexibility to use transistors of different physical sizes and
styles; i.e, the amp can be upgraded or retrofit as desired.

You're losin' it... no PCB at RF frequencies means wires and
uncontrolled inductances / resonances all over the place causing
instabilities... resulting in oscillations. Why don't you think any
commercial amps are built your way.
Great idea Frank... LOL... you're truly a great engineer!


How do you think amps and transmitters were built before the PCB was
invented? In fact, how do you think most broadcast transmitters (many
of which are still in use today) were built? By mounting a 4CX5000 on
a PCB? Why do you think the old chassis-wired Heathkits command a much
higher price than the later versions with more features but built with
PC boards? And did you know that UHF transmitters also existed long
before PC boards, were also constructed with point-to-point wiring,
and worked without the problems you claim are inevitable.... on HF?

I can cite dozens of examples of power equipment, both audio and
radio, that have histories of failure due to the use of PC boards
instead of hard wiring. I think Peavey is about the worst offender in
that department, in my own personal experience.

So you can fabricate any unfounded fear-tactic you like, the fact is
that PC boards (including the newer epoxy boards) just aren't adequate
for any high-power applications, let alone RF power applications. And
point-to-point wiring is a time-tested method that only seems to cause
problems for those who need a computer to tell them how to route the
wiring.

On a sunny day (20 Sep 2006 02:53:13 -0700) it happened "Telstar Electronics"
wrote in
om:


Frank Gilliland wrote:
No PCB = no cracked traces, copper seperation, no burnt boards, better
heat dissipation, more efficient conductors, etc, etc. Let's face it:
replace the power transistors more than twice on a PCB and your board
(and therfore your amp) is garbage. Not only that, but it also allows
the flexibility to use transistors of different physical sizes and
styles; i.e, the amp can be upgraded or retrofit as desired.

You're losin' it... no PCB at RF frequencies means wires and
uncontrolled inductances / resonances all over the place causing
instabilities... resulting in oscillations. Why don't you think any
commercial amps are built your way.
Great idea Frank... LOL... you're truly a great engineer!

www.telstar-electronics.com

Well, not exactly, I had in the long ago past a nice 40MHz army transceiver,
toobes!!! (called '32set' IIRC) 40 MHz FM full of toobes and no PCB anywhere.
My own 500W linear PEP with toobe had no PCB either.
If you go to a real shortwave station, 10kW and up, they use big plumbing,
big toobes sometimes... (these days transistors too in modules OK).
PCB (an as already mentioned by somebody): the thickness of PCB traces becomes
a BIG issue especially if you run 1kW at 12V, a few milli-ohm will give
you big i^2 x R losses.
So copper strip is better anyways, lower current, and higher voltages, FETS,
means lower losses, you will need the switch-mode to get the higher voltage.
Switch-mode design 50V many amps is an art in itself, I have done switchmode
design for a company, it will take you study and time, and likely a few
transistor failures.

Soldering copper strips to these transistors will require you to support these
with proper spacers, so as not to mechanically load the transistors too much.
Else vibrations will rip the connections right of over time.

I like Franks idea, it is a lot like this one:
http://www.ibelings.com/n4ip/mrf157.html
I looked up the price of those FETS, 475$ each :-)
But I also found a pair on offer for less then 60$, was already gone however.
http://www.sphere.bc.ca/test/rf-semis.html
other interesting stuff there too:-)
In my school days I used to sell Motorola parts...... to finance my hobby.


So, anyways, long before the kids had PeeSeeBees the big boys were using
copper [wiring], and it did not [always] oscillate.
And in the old toobe times the voltages were more 'electrifying' too, mine
ran on 1kV, some used much higher voltage power supplies, dangerous these big
capacitors.
So the Telstar amp is just a small toy..... compared to what was done already
in and just after WW2.

But do not let that put you off, it looks like a nice amp.
And Frank will still have to build his ;-)


BTW you Americans have 110V, I had some BUZ44A (IIRC) MOSFETS that can do
500V DC, these oscillated (unwanted) around 20MHz, one could just plug it in
for a base station.... No voltage converter needed, not even a transformer.
Not sure if something like BUZ44A can be used as an amp.... at 27MHz.
http://www.datasheetarchive.com/data...rticle=1048164
probably to much input capacitance 1600 pF.....

But looking around for a nice FET may be worth it.