RadioBanter - View Single Post

September 30th 04, 06:27 PM

(Brian Kelly) wrote in message . com...
PAMNO (N2EY) wrote in message ...
In article ,
(Brian Kelly) writes:
(Len Over 21) wrote in message
...
In article ,

(Brian Kelly) writes:
. . . . . . .
What you *did* claim was that you could operate within 200 Hz of a band edge
and know you were inside, using certain '50s/60s vintage equipment. Which
is a reasonable claim for the equipment involved.

btw, back in 1975 or so I designed and built a "digital dial". The way it
worked was that it used TTL 74192 presettable up-down counters to count the
tunable oscillator. You'd adjust dip switches for the offset and direction of
each band and mode. Its time base was a 400 kHz xtal, easily zeroed to
within a
few Hz of WWV. The thing normally read out in 100 Hz increments but could be
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 and got an A in the course.

Lab course at Penn?

Independent design project. Made the circuit boards meself and all.
Still have it, still works. Don't use it much though, because one
thing I learned in the process was that I prefer an analog dial for
most purposes. Just a personal preference. Which is one of the big
reasons to homebrew - you get to indulge personal preferences.

And yes, you could easily reset it to 100 Hz.
10 Hz took a steady hand.

But it could be done with a Collins.

Later I saw a better design. It sampled and counted all the oscillators in a
rig, and displayed the total. No presets to adjust - set the timebase to WWV
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.
. . . . .
electrical QRN noise floor on the band under consideration. Which is
easy enough to check. Welome to the realities of "phase noise "insofar
as amateur radio operation is concerned" Sweetums.

Sort of.

Close enough for an M.E.?

See below for the big issue.

referring to the number of decibels
below the "carrier" (center frequency reference, not a modulated
carrier per se). The "crud" (as you term it) is quite far down in
relative power and certainly won't affect morse code reception of an
on-off keyed station's carrier.

Wrong. Incorrect. Not true at all in the real world of HF radio.

Len has just demonstrated, once more, that he just doesn't get it.

You expected anything else??
. . . .

Not really.

decade on cellular telephony techniques has been enormous
worldwide. It's only natural that industry advertisements, from sub-
system components to full systems, emphasize a low "phase noise."

Has nothing to do with the subject at hand, which is HF amateur radio.

Spank.

As far as on-off keyed radiotelegraphy, your mention of "phase noise"
as being "crud" in synthesizer frequency control is akin to making
a big case for gold-plated music system speaker wires. :-)

Wrong again, Len.

What a goofball . . .

The audiophile *market* is full of pseudotechnology - driven by the
fact that there's $$ involved. But there's also some good stuff too,
driven by folks who like *music*.

I like music.

responses...one of the papers I wrote at RCA was on quick
identification of such possible spurs (not the first, but it was a
very quick way to determine them).

Misses the point completely.

Spank.

Here's what *really* happens:

In an ideal superheterodyne, all the oscillators would generate pure, steady
injection signals. In reality, there is always some imperfections in those
oscillator signals. In modern frequency synthesizers, particularly PLL
types,
the imperfection takes the form of noise sidebands on the oscillator signal.

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.

That's just one source of phase noise.

Now even first-generation designs had noise sidebands many dB below the desired
LO signal. Someone who doesn't really understand the situation might react as
Len does, saying that such low-level noise can't have any real effect on receiving the desired signal . . . snip . . . And he won't
hear the low-power limited-antenna less-than-a-microvolt stations he's trying to work. All the Inrads and DSP in the catalogs won't do
any good in such a situation.

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.

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.

Which is what USENET usta be all about . .

smaller increments...:-)...but I also have to play to the common
denominator of technical expertise in here.

1 Hz is common in modern manufactured amateur equipment. But that's not really
the issue.

Of course it isn't. This sort of overkill ticks me off, it's BS tossed
out by the advertising geniuses to reel in the no-clues and
overcomplicates the equipment for the rest of us.

The issue is that some specifications are much more important than
others. And that getting the signal on the air is the goal...

increments Sweetums, the best you can do with the thing is tune it to
the nearest 100 Hz increment yes? Of course you silly old thing. I've
never seen an R-70 in the flesh so tell me, are those actually Nixies
in the display for God's sake?!

R-70 is a pretty good receiver.

OK, the R-70 "happened" during my radio hiatus and went past me so I
poked around the Web for info on it. Looks like it is a decent
performer. Problem is that at this point it's OLD, it comes out of the
same generation of equipment as the TS-930/940 did both of which now
suffer well-known aging/reliability problems. I've had more than my
share of those with the 940 so I wouldn't give an R-70 the desk space
if somebody gave me one gratis. If Sweetum's R-70 is still ticking
along without problems good for him.

Almost qualifies as a boatanchor now....

Hang classic tags on it.

One of the problems with older solidstate equipment is that much of it
used custom parts for which the only sources are the manufacturer (if
they still support the unit) or junker units. If there was a weak
spot, finding a junker with a usable part maybe hopeless. The Kenwood
TS-440s reputedly has this problem in its display.

Turns out Icom has a neat 3-loop PLL arrangment, doesn't
go into DDS or Fractional-N at all. Minimal phase noise and no
discernable "crud" anywhere within full tuning range.

How many points did Len get with it in the last CQWW? Or even the last SS or
Field Day?

Or in RRAP.

Okay, so your spiffy-schmiffy 1 Hz resolution "xcver" is "guarnateed"
accurate because it has a "digital dial?" I don't think so.

Nobody claimed that it was accurate. It *is* precise, however. Big difference.

Spank.

Exact 1 Hz
settings imply 100 PPB (Parts Per Billion) accuracy of the master
reference oscillator.

Yo Sweetums: I did a refresh on the 847 specs, the thing can display a
freq to 0.10 Hz resolution. Apologies for tossing out bad info. Heh.

Precise but not necessarily accurate.

Let's see - 1 part per million is 10 Hz at 10 MHz. Or 1000 parts per billion.
So 100 parts per billion is 1 Hz at 10 MHz.

You will NOT be able to hold such accuracy
and be believable to anyone who has worked to such accuracies in
crystal oscillators. Certainly not for the ham consumer market.

Nobody is claiming that kind of *accuracy*. Only that kind of *precision*.

"He can wriggle, he can squirn . . . "

...."says to push on"..

Of course there's an easy and quick check of all this. Just tune in WWV and see
what the fancy digidial says when you zero beat the carrier in SSB mode. That
will tell you how accurate the reference oscillator is. Traceable directly to
NIST via the F2 layer. If you're at all careful you can get to the point where
the S meter needle is slowly fluctuating as the frequency/phase difference
wanders...

Is there anybody who knows what's up who *doesn't* do that
periodically??

I rather prefer what I've been exposed to since 1963 on frequency
control methods...

Still living in the past...

That's all he has left. Not counting Burke.

said. Like, I could ask you "how's the zeta of your control loop"
and you would be out to lunch, cussing and hollering "bafflegab!"

No Sweetums, not at all, that's not the way I work. You're being silly
again. If by any chance I ran into an arcane topic like that in which
I had any interest whatsoever I'd ask an EE to uncurl it for me.

Engineering 101: Don't reinvent the wheel. They even taught us EEs that one.

He's a breed I'm quite (unfortunately) familiar with: the old time
military aerospace out-in-the-shop bench tech types. Doesn't matter
what narrow fields they worked in, oleo struts, control surface
actuators, flight control electronics, radar, comms electronics, pilot
relief piping, their syndromes are all the same. They had these little
niches in which they beavered away on their little piece of the
overall much bigger job or project or whatever it was. Eventually,
because of their complete immersion in their niches, they come to the
conclusion that it all would come apart save for their "expertise" and
anybody who isn't particularly up to speed on the nits and grits of
whatever they were buried in are unworthy no-clue clods. Sweetums is a
perfect example of these windbags.

So along comes somebody like myself, a fish-out-of-water mechanical
engineeer in this group who readily concedes non-expertise in topics
like circuit design and even worse from his twisted perspective has no
interest at all in doing any "synthesizer development" sorts of things
so he bores in on me with his bafflegab. Which highlights at least two
of his fundamental deficits: (A) He's mentally incapable of conceding
a lack of "technical expertise" on any subject involving radio,
particularly ham radio and (B) He's equally incapable of understanding
why professionals like thee and me feed each others' expertise and
work together to get from here to there and *don't* reinvent wheels.

Just like my friend from high school:

Time for a radio story...

Back in high school I knew a local ham down Collingdale way who was always
working on a pet project. Same age as me, saw him in school every day. Had all
kinds of grand ideas of how he was going to build the next generation
state-of-the-art ham rig. All solid-state, full features, all bands, all modes,
etc.

Now this kid was no dummy and his ideas were basically very sound. But he
didn't have anywhere near the resources or practical experience to actually
finish anything. He'd draw all kinds of schematics, spin all kinds of yarns and
sometimes even gather some parts. But build a working rig? Never happened. Not
once. When he *did* get on the air, it was with borrowed equipment that he
conned some local ham into lending him "temporarily". Until said local ham had
to come over and take it back. I made the mistake of loaning the kid a QST,
which I never saw again. I learned fast.

Meanwhile, those of us willing to make do with less than "SOTA" were on the air
and having fun and QSOs while he pontificated.

That was about 35 years ago but the lesson is still valid: All this bafflegab
doesn't make one QSO.

For some reason I was reminded of him. He sounded just like Len..

A gooder for certain.

SPAAAAAANK!

Now take a break from your bafflegabbery Sweetums and let's play in my
field of professional expertise this time. Demonstrate your level of
technical competence by solving a very real-world electronics design
problem. Assume that you have a one inch diameter x 1/16 inch wall x
eight foot long 6061T651 aluminum tube fully restrained at one end
with the other and dangling horizontally in the wind. Calculate the
maximum wind speed which will not produce permanent deformation of the
tube.

That's easy! Would take me about sixty seconds to get the answer.

Maybe. I can't do it in sixty seconds at the moment, I dropped my
slide rule again and have to realign it before I do the speed run so
QRX . . . .

We both know Sweetums won't touch it with a ten foot pole even though
it's a sophmoric simple exercise. He doesn't know where to even start
to approach the problem let alone solve it so he'll diss it as
irrelevant. Typical and completely predictable sub-professional
defensive behavior.

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.