RadioBanter - View Single Post

October 1st 04, 08:14 PM

In article ,
(Brian Kelly) writes:

(N2EY) wrote in message
.com...
(Brian Kelly) wrote in message
.com...
PAMNO (N2EY) wrote in message
...

switched to 10 Hz or 1 Hz. Its accuracy was dependent on how well you
set
the
time base and presets. Could be used with almost any rig. Hooked it up
to a
75S3

I'll bet I know where the S3 came from . . .

and got an A in the course.

Lab course at Penn?

Independent design project.

._.

Made the circuit boards meself and all.

Lotta jollies there if yer into such things. I "burned" a number of
homebrewed circuit boards, late '60s? Something like that. Making PCBs
then was basically a drafting and photographic process which
"integrated"nicely into my darkroom "assets" so I went at it a few
times. Translate the circuit diagram in QST to a physical layout for
openers. Yeah, they can draw circuits which show conductors leaping
over other conductors without shorting them but that don't work on
single-sided boards dammit! Which all homebrewers could do then. Dunno
how you did yours but there were complete PCB "kits" available from
Kass and Radio Shack when I did mine.

They provided sheets of transfers with "donuts" for wire and component
connections and IC pinouts all of which were layed out on a
transparent film. Then ya *very carefully* connected all the dots with
thin tape to make the conductor traces. Tedious. Net result was a 1:1
photograhic negative of the circuit. From there it went into the
darkroom where the negative was positioned over a piece of sensitized
board stock and exposed, developed, neutralized and washed just like
all photos are developed even today. I did a few boards which I
sensitzed myself.

The rest was easy. Drill all the holes, trim the board to size and
stuff it with the components. Then go back and solder-patch all the
busted traces! Hee!

I guess I did ten boards all told. Three keyers, one a monster K3JH
developed which was first large-capacity memory keyer, several
stripline SWR bridges, a vacuum relay QSK TR switch, etc. I think I
showed you some of those "works of art" before I dumstered all that
old crap. I have a yen now to build a couple more widgets using
homebrewed PCBs but so far I have not been able to find the board
stock or chemicals in hobby quantities.

Go to FAR Circuits for a huge collection of PCBs available for
all those magazine article projects. Ready-made wiring. FAR
is run by a ham.

Don't keep old "crap." Save that to toss at NCTAs in newsgroups.

The 74192 and other TTL family chips were hot stuff 30 years ago when
I was doing that project. You can still get pin-compatible parts
today.

I fed the aformentioned dumpster a *shoebox* full of those old 7400
series chips . . .

Tsk. Well, if you don't know how to use them, toss 'em.

You are PCTA extra royalty. Save the TUBES, recycle 'em into
world-beating contest-quality radios to win all those accolades!

That leaves Sweetums and his half-vast "experience" out. Long-haul
military HF comms are channelized and if a station is weak they just
twist the Variac clockwise. 40kW with rhombics just to push RTTY from
Tokyo to the west coast . . SPARE me . . !

You "know" all about military communications? Of course you do.
You were of the royalty that was never IN.

You've never worn an AN/PRC-104 HF manpack raddio, have you?
Big, powerful 20 W out on HF, operational with U.S. land forces
now. Same RF power out as the SGC 2020 being made in Belleview,
WA, by the company started by Don Stoner and Pierre Goral (both
SK, sadly, long-time hams).

The full manual for the 2020 is on the SGC website in case you
wanted to find out what is done TODAY. I could tell you were to
get the four full government manuals for the PRC-104 free but you
will only tell me "where to go." :-)

The "4 KW" and (later) "40 KW" pushing from Tokyo to San Fran or
anywhere else in ACAN was for SIDEBAND. The 12 KHz first
variety of SSB carrying four voice-bandwidth circuits. If you wanted
24/7 communications on HF back a half century ago, you needed
power and antennas. You spit on that fact, relegating such "menial"
tasks to "drudges" while you brag about "eating at the captain's
table."

It's no big deal at all. As far as the "math" goes any kid who has a
decent grip on 9th grade alegebra can hoof thru it, this is not double
integral or tensor analysis country. All one needs to pull it together
is the material physical properties and the ability to jiggle a few
simple algebraic equations which are only a half-step beyond jiggling
Ohm's Law. All of it is readily available out on the Web and it can
all be done with a pencil and a calculator.

That's why Phil Smith came up with the Smith Chart back before
WW2. :-)

Not for designing antennas...for easing the work required by
Bell Telephone on long-distance transmission lines. Work that
required slide-rules and mechanical desk calculators (sometimes)
due to pocket calculators not being invented yet. :-)

For my own part I've gotten into semi-automating the whole process in
order to design widgets like tapered aluminum yagi elememts,
fiberglass quad (squalo?) spreaders, masts and towers. I run a LISP
rountine in Autocad to come up with the cross-sectional properties
then diddle the rest in Excel or Mathcad or a slick little $50
shareware program called "DTbeam" which is a finite elememt analysis
beam analyzer. The M.E.'s version of a Java-based Smith Chart solver.
Sort of.

Tsk. You should use Roy Lewallen's EZNEC. Roy is a long-time
ham. EZNEC is advertised in QST.

USN Postgraduate School folks came up with the Numerical
Electromagnetic Code (NEC) which is all free to anyone (no
copyright). Too bad the USN types at the "captain's table"
didn't mention that to you...