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.

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

+++
+++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
***************

Below about 1 KW, PCBs are adequate. In the 10 to 20KW range forget
laminates. You would have to plate at least 3 ounce if not 4 ounce
copper. Beisdes most laminates will have tremendous problems with RF
currents at these power levels. AIr dielectric or even ceramics
provide a better solution.

Also I believe Frank never mentioned the actual power out of his
design.

james