In article ,
(Brian Kelly) writes:

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

W3ABT, now N3KZ

and got an A in the course.

Lab course at Penn?

Independent design project.

._.

It could also be set up as a straight counter by setting the preset to zero.

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.

My method was very simple - and I did double-sided ones.

1) Lay out both sides on grid paper
2) Lightly center punch holes on both sides
3) Cover both sides with transparent packaging tape
4) Use Xacto knife to cut out non-copper parts of tape
5) Ferric chloride bath to etch
6) Wash, remove tape
7) Drill through holes

Some what crude looking but they all worked. To save layout time, I made each
counter decade on one board, then wired the decades together.

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!

My method was quick/n/dirty but it worked. No busted traces either.

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.

I have the board stock. Ferric chloride is a different matter...

and you're done. Could go to 1 Hz if you were willing to have it update
once
per second.

Neat! (no, I'm not willing to wait a second for the nummers to come up
. . ! )

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 . . .

They were da bomb in their time but today it would be easier to do it other
ways. Or just do a mechanical dial...

Wait a minnit, if there are sideband signals on the LO output the
inference seems to be that the carrier is being modulated.

That's exactly what's going on.

By something. What something?

All kinds of somethings. Here's just one:

In a PLL synthesizer, the VCO control voltage may wander a bit for a
variety of reasons. Say you have a design where a voltage swing of 5
volts causes the VCO to move 5 MHz. *Any* variation in that control
voltage, from *any* source, will cause the VCO frequency to wander a
bit. 1 millivolt variation gives a shift of 1000 Hz, 1 *microvolt* of
variation gives 1 Hz, etc. Remember that the control voltage is a DC
signal and the rest is obvious.

Not quite. I gotta chase down the links Dave supplied and keep
digging.

It's all there. Main point is simply that the output of many synthesizers isn't
nearly as clean as what comes out of xtal or self-controlled oscillators of
good design. Which is why this wasn't a problem in, say, a Ten Tec Corsair 2.

That's just one source of phase noise.

OK

Note also that most modern rigs synthesize *all* the LOs, so the effect is
magnified.

Typical Ikensu box starts out by converting the input to about 70 MHz. This
permits covering ~DC to 30 MHz without gaps. Also makes image rejection really
good with just a lowpass filter on the input. Of course the LO tunes 40 to 70
MHz, but that's not a problem with a synthesizer.

Keeping the synthesizer *clean* is another matter.

Then the 70 MHz is converted down to the first filter frequency - typically
8.83 MHz. Requires another oscillator - typically synthesized because that way
you can do things like PBT easily. Then BFOs, and such....all synthesized.

That's why phase noise is important to hams.

Huh: I learned a bit from this post.

I hope so!

The upshot of all of it is that in real-world hamming, we often have
to deal with bands full of strong signals, yet we want to hear the
weak ones.

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 . . !

Just a different environment. Army of Occupation takes over JA in 1945, one of
the first orders of business is good comms back to DC and Arlington. Pick out a
good site, put up the poles, haul up the diamonds, fire away. All on the
taxpayer's nickel. Well spent money but has little to do with the reality of
self-funded avocational radio.

I've run into more than a few hams who say they "hate contests because
they make the bands so noisy". What's really going on, in at least
some cases, is that the effects of so many strong signals on the air
all at once raise the apparent noise floor of their *modern*
transceivers, in part due to phase-noisy oscillators in the
contest-haters equipment.

"If ya can't take the heat go up the band!"

Point is, they *could* coexist with better equipment.

One can spend two lifetimes diddling frequency synthesizers and such
but if whatever freq pops out of his gem doesn't make it to the
airwaves via an engineered radiator and it's support structure one
might as well have been a lifeguard in the Mohave desert.

And THAT'S the game!

73 de Jim, N2EY

btw - the way I'd solve the problem would be to email you for the
solution.

. . . boink . . POINT!

"Wouldn't it be easier for *me* if *you* did it?"

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.

Typical materials info source:

http://www.matweb.com/SpecificMateri...&group=General

Here's a taste of the number-crunching:


http://hsc.csu.edu.au/engineering_st...bending/bendin
g_stress.html

Like I said - don't reinvent the wheel....

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.

http://www.dtware.com/

Nice! But I prefer Microstation...

73 de Jim, N2EY