Chip with simple program for Toy

[Joe McElvenney]

Hi,

I'd like to design a 10W VHF P.A., but all I've ever designed were
some LNAs and other low powered amplifiers. So now for the dumb
question: How do I know what matching circuit components to chose,
since now I have to be concerned not only with the L and C circuit
values themselves (to obtain a good power match), but also the highest
voltage level that these components must survive at the output of the
RF P.A. (so that the whole P.A. output circuit does not go up in
smoke). How do I calculate what voltages that these components must be
rated to, and select my P.A. passives accordingly?

Obviously the simple solution is to copy someone else's
design for the same frequency and power level from a journal or
handbook. But, should you wish to do it on your own, you will need
to read the literature and the name that immediately springs to
mind is Motorola. They have an excellent book by Dye and Granberg,
"Radio Frequency Transistors : Principles and Practical
Applications" that lays it all out and several application notes,
such as AN721 on matching, if you don't mind a little maths.


Cheers - Joe

 

[Sjouke Burry]

Mike wrote:

"default" wrote in message
news:8fc0q1p9t7do4t9kluch73remoccb7p4c3@4ax.com...


What piques my curiosity is why an inordinate number of electronics /
electrical engineers seem to gravitate to "playing with their food."
Baking Bread, Cooking, Making Sausage, Making Pickles, Brewing Beer
and Wine . . . etc.


After reading the posts in this thread, I'm convinced most of them should
stick to the bakery. The question isn't just why, it's "What the hell are
they thinking?"

-- Mike --


They think: How the hell does that work?? Aftrer finding

out they have of course to eat it.(Or admit failure).
But 80% of the fun is finding out.

 

[Rich Grise]

On Wed, 14 Dec 2005 20:43:05 +0000, Peter Hucker wrote:

On Wed, 14 Dec 2005 17:31:31 -0000, ah <splifingate@gmail.com> wrote:
Peter Hucker wrote:
On Mon, 12 Dec 2005 08:53:31 -0000, ah <splifingate@gmail.com> wrote:
Peter Hucker wrote:
On Sat, 10 Dec 2005 21:38:01 -0000, Rich The Newsgroup Wacko <wacko@example.com> wrote:

Visualize Whirled Peas!

I'll need some marajuana first.

You'll need a slight bit more'n that, Peter.

"Some" is not a specific quantity.

But easily identifiable--in this context--as not nearly enough.

"Some marajuana" is never anywhere near specific.

"Dope will get you through times of no money better than money will get
you through times of no dope."
-- Fabulous Furry Freak Brothers

"Dope will get you through times of no pussy better than money will."
-- some cow-orker in the EMR shop at Beale AFB, CA, ca. 1974

Cheers!
Rich

[1] EMR = Electromagnetic Reconnaissance. Or, depending whom you're
talking to, Educable Mentally Retarded. ;-P

 

[JosephKK]

Jasen Betts wrote:

On 2005-11-29, Davy <zhushenli@gmail.com> wrote:
Hi all,

reg[7:0] register;
The register contains data like
[0 0 0 1 0 1 0 1]
And I want to know the number of the zeros before the first 1
(in this example is 3 zeros).

How to do this in a combinational logic?

what output do you want?




you really should not do his homework for him.

--
JosephKK

 

[Panther]

Yeah I will proabbly do that if nothing else works. THanks
"Jasen Betts" <jasen@free.net.nospam.nz> wrote in message
news:564c.43a9ac5a.65985@clunker.homenet...

On 2005-12-21, Panther <black@cat.com> wrote:

Hello everyone

I have a few queries. It shows a graph of voltage vs time. The x-axis
represents time, and I know that. What I'm trying to do is this: I have
some
screen grabs of voltage discharge/charge curves, and I'm trying to find
the
voltage after 5 time constants (I know where). But I need to read off the
voltage at that point, how do I do that?

Time constant is resistance times capacitance
Time in seconds, resistance in ohms, capacitance in farads.

Does something called "Y1 Gain"
make any sense? I've no idea how to convert that nonsense into voltage.

AIUI that will scale the output reading.

if at some point the voltage was at a known level all other results will
be
proportionate to that reading.

Bye.
Jasen

 

[Blake]

<Searcher7@mail.con2.com> wrote ...

Can anyone tell me if there is a glue that I can use to attach 18 or 20
gauge wire to brass, bronze, or nickel for a solid electrical
connection?

You might try a conductive epoxy like this one

http://tinyurl.com/dtqs3

 

[JeffM]

Can anyone tell me if there is a glue that I can use
to attach 18 or 20 gauge wire to brass, bronze, or nickel
for a solid electrical connection?
Darren Harris (Searcher7 @ mail.con2.com)

A previous thread on conductive epoxies:
http://groups.google.com/group/sci.electronics.design/browse_frm/thread/9578754e9a533059/1967afdbfd09deac?q=oxidation+*-increase-in-resistance+high-initial-resistance+Not-ready-for-prime-time+low-power-apps-in-benign-envireonments

 

[Jasen Betts]

On 2006-01-02, Searcher7@mail.con2.com <Searcher7@mail.con2.com> wrote:

Can anyone tell me if there is a glue that I can use to attach 18 or 20
gauge wire to brass, bronze, or nickel for a solid electrical
connection?

I've used a hot-melt product called "solder"

Bye.
Jasen

 

[Dave Oldridge]

"billcalley" <billcalley@yahoo.com> wrote in news:1136148463.132269.164130
@g49g2000cwa.googlegroups.com:

I realize that dipoles are balanced antennas, but does the rig
itself still need an RF ground too? (I know the radio always needs a DC
ground, of course). How about if the dipole is being used as a
non-loaded "all band" antenna (IE: RIG--TRANSMATCH--LADDER
LINE--DIPOLE) -- would this affect the need for an RF ground on the rig
for operation in the dipole's non-resonant bands? Or is no RF ground
_at all_ required with a dipole; unlike when using random wires or
verticals, and other such un-balanced antennas?

If the antenna is TRULY balanced and the feedline dressed well away from it
at right angles you should have no common-mode currents on the feedline.
That's the ideal case and in that ideal case you need no RF ground at the
radio. The ideal case, however, rarely ever exists in practice.

And end-fed wires can be a whole different ball game. I had to use a 16
foot counterpoise once to "ground" a rig in a 2nd story location when I
end-fed a very long wire with it.



--
Dave Oldridge+
ICQ 1800667

 

[Alan B]

On Mon, 2 Jan 2006 08:48:52 +0100, via
<Z9auf.467$X25.180765@news20.bellglobal.com>, "Ken"
<lerameur@sdom.com> spake thusly:

Hello,

I was wandering if the following is possible.
I have a huge voltage 3kvolt,

3kV is high, but hardly huge.

when is passed through a coil my voltmeter is
showing me negative voltage. I would like to phase shift this or invert this
so to get positive voltage How do I go about this?
...I heard that inthe 70's, some cars where negatively based, and used such
converters to get positive. now I believed everything is positive.

Start with a study on the characteristics of AC and DC. Check back
when you know a little about that topic. Have fun!

 

[Ken]

when is passed through a coil my voltmeter is
showing me negative voltage. I would like to phase shift this or invert
this
so to get positive voltage How do I go about this?
...I heard that inthe 70's, some cars where negatively based, and used
such
converters to get positive. now I believed everything is positive.

Start with a study on the characteristics of AC and DC. Check back
when you know a little about that topic. Have fun!

Actually I meant current not voltage. the ampmeter shows negative after the
inductor (coil).
And this is pulse DC not AC, so shifting by PI wont do it, I guess I need
to invert this.


ken

 

[billcalley]

Thanks Guys -- I really appreciate the clarifications on grounding! It
sometimes gets a bit confusing for me.

Best Regards,

Bill

 

[Gareth]

Ken wrote:

when is passed through a coil my voltmeter is
showing me negative voltage. I would like to phase shift this or invert
this
so to get positive voltage How do I go about this?
...I heard that inthe 70's, some cars where negatively based, and used
such
converters to get positive. now I believed everything is positive.

Start with a study on the characteristics of AC and DC. Check back
when you know a little about that topic. Have fun!



Actually I meant current not voltage. the ampmeter shows negative after the
inductor (coil).
And this is pulse DC not AC, so shifting by PI wont do it, I guess I need
to invert this.

Is there a good reason why you can't just connect the meter the other
way round?

Gareth

--
-----------------------------------------------------------------------
To reply to me directly:

Replace privacy.net with: totalise DOT co DOT uk and replace me with
gareth.harris

 

[Bob]

"Ken" <lerameur@sdom.com> wrote in message
news:UJeuf.637$X25.248638@news20.bellglobal.com...

when is passed through a coil my voltmeter is
showing me negative voltage. I would like to phase shift this or invert
this
so to get positive voltage How do I go about this?
...I heard that inthe 70's, some cars where negatively based, and used
such
converters to get positive. now I believed everything is positive.

Start with a study on the characteristics of AC and DC. Check back
when you know a little about that topic. Have fun!


Actually I meant current not voltage. the ampmeter shows negative after
the inductor (coil).
And this is pulse DC not AC, so shifting by PI wont do it, I guess I
need to invert this.


ken

Oh, that's different.

Start with a study on the characteristics of AC and DC. Check back
when you know a little about that topic. Have fun!

Bob

 

[Roy Lewallen]

Dave Oldridge wrote:

If the antenna is TRULY balanced and the feedline dressed well away from it
at right angles you should have no common-mode currents on the feedline.
. . .

That only prevents one of the two ways common mode current can be
created, by coupling. It can also be created by conduction. A common
example is a coax-fed dipole, where the current in the outer feedline
conductor splits between the antenna conductor and the outside of the
coax. An equivalent problem can occur when a dipole is fed with
symmetrical line such as ladder line, and one conductor of the line is
connected to the rig's chassis at the rig end. The current on the inside
of the chassis is equal to the current from the "hot" conductor, and
this splits between the transmission line conductor and the outside of
the chassis. A detailed explanation of conducted common mode current can
be found at http://eznec.com/Amateur/Articles/Baluns.pdf.

Roy Lewallen, W7EL

 

[Dave Oldridge]

Roy Lewallen <w7el@eznec.com> wrote in
news:11rj9uu7bkogd37@corp.supernews.com:

Dave Oldridge wrote:

If the antenna is TRULY balanced and the feedline dressed well away
from it at right angles you should have no common-mode currents on
the feedline.
. . .

That only prevents one of the two ways common mode current can be
created, by coupling. It can also be created by conduction. A common
example is a coax-fed dipole, where the current in the outer feedline
conductor splits between the antenna conductor and the outside of the
coax. An equivalent problem can occur when a dipole is fed with
symmetrical line such as ladder line, and one conductor of the line is
connected to the rig's chassis at the rig end. The current on the
inside of the chassis is equal to the current from the "hot"
conductor, and this splits between the transmission line conductor and
the outside of the chassis. A detailed explanation of conducted common
mode current can be found at
http://eznec.com/Amateur/Articles/Baluns.pdf.

Roy Lewallen, W7EL

Still, if the antenna is TRULY balanced (a situation that only rarely
actually happens), you won't get common-mode currents. I've never had a
problem with them with well-grounded (from an RF standpoint) ground-
mounted verticals either.

Essentially this is why I recommend using open wire or twinlead and
feeding it through a proper balanced-line tuner. Years ago, I built an
amplifier that literally had a balanced line output and fed a 600-ohm
feeder direct off two taps on its output coil. That feedline was only
ten feet long and I worked a TON of 80m DX an the inverted vee that it
connected to. And I could always tap the coil so as to have ZERO RF in
the shack (though my landlady's little 7.5 watt light bulbs used to light
on some frequencies when the house wiring picked up direct from the
antenna).


--
Dave Oldridge+
ICQ 1800667

 

[chuck]

Is it not true that if the currents on the transmission line are unbalanced
(i.e., unequal on the two conductors) then the transmitter must already be
connected to ground? If not, what is the path of the differential current?

Chuck

Dave Oldridge wrote:

Roy Lewallen <w7el@eznec.com> wrote in
news:11rj9uu7bkogd37@corp.supernews.com:

Dave Oldridge wrote:

If the antenna is TRULY balanced and the feedline dressed well away
from it at right angles you should have no common-mode currents on
the feedline.
. . .

That only prevents one of the two ways common mode current can be
created, by coupling. It can also be created by conduction. A common
example is a coax-fed dipole, where the current in the outer feedline
conductor splits between the antenna conductor and the outside of the
coax. An equivalent problem can occur when a dipole is fed with
symmetrical line such as ladder line, and one conductor of the line is
connected to the rig's chassis at the rig end. The current on the
inside of the chassis is equal to the current from the "hot"
conductor, and this splits between the transmission line conductor and
the outside of the chassis. A detailed explanation of conducted common
mode current can be found at
http://eznec.com/Amateur/Articles/Baluns.pdf.

Roy Lewallen, W7EL

Still, if the antenna is TRULY balanced (a situation that only rarely
actually happens), you won't get common-mode currents. I've never had a
problem with them with well-grounded (from an RF standpoint) ground-
mounted verticals either.

Essentially this is why I recommend using open wire or twinlead and
feeding it through a proper balanced-line tuner. Years ago, I built an
amplifier that literally had a balanced line output and fed a 600-ohm
feeder direct off two taps on its output coil. That feedline was only
ten feet long and I worked a TON of 80m DX an the inverted vee that it
connected to. And I could always tap the coil so as to have ZERO RF in
the shack (though my landlady's little 7.5 watt light bulbs used to light
on some frequencies when the house wiring picked up direct from the
antenna).

 

[Roy Lewallen]

Dave Oldridge wrote:

Still, if the antenna is TRULY balanced (a situation that only rarely
actually happens), you won't get common-mode currents.

That's true only if by "balanced" you mean that the two feedline
conductors carry equal and opposite currents. In that case, common mode
current is zero by definition. But if you really mean symmetrical, as
most amateurs do when they say "balanced", you certainly can have common
mode current.

A detailed explanation of how that happens is in the article at
http://eznec.com/Amateur/Articles/Baluns.pdf, and the article by Walt
Maxwell, W2DU at http://www.w2du/r2ch21.pdf which is referenced at the
end of the first article? Note particularly figures 3 and 4 of the
Baluns.pdf article.

I've never had a
problem with them with well-grounded (from an RF standpoint) ground-
mounted verticals either.

The reason this provides balanced feedline currents is that the
impedance to ground at the base of the antenna is much less than the
impedance looking back from the feedpoint down along the outside of the
feedline. Consequently, the large majority of the current from the
inside of the coax shield flows to ground rather than down the outside
of the coax. And laying the coax on the ground keeps coupled common mode
current down.

Essentially this is why I recommend using open wire or twinlead and
feeding it through a proper balanced-line tuner.

That combination will produce a truly balanced system with no common
mode current. But it's not the only way.

. . .

Years ago, I built an

amplifier that literally had a balanced line output and fed a 600-ohm
feeder direct off two taps on its output coil. That feedline was only
ten feet long and I worked a TON of 80m DX an the inverted vee that it
connected to. And I could always tap the coil so as to have ZERO RF in
the shack (though my landlady's little 7.5 watt light bulbs used to light
on some frequencies when the house wiring picked up direct from the
antenna).

 

[Dave Oldridge]

Roy Lewallen <w7el@eznec.com> wrote in
news:11rlqiv2po14n6d@corp.supernews.com:

Dave Oldridge wrote:

Still, if the antenna is TRULY balanced (a situation that only rarely
actually happens), you won't get common-mode currents.

That's true only if by "balanced" you mean that the two feedline
conductors carry equal and opposite currents. In that case, common
mode current is zero by definition. But if you really mean
symmetrical, as most amateurs do when they say "balanced", you
certainly can have common mode current.

No, I mean ELECTRICALLY balanced. And with the feedline at right angles
to the antenna so that it doesn't pick up anything by induction. It's a
tricky thing to do, yet back in the old days hams used to feed dipoles or
extended double zepp antennas with open wire line and not get much RF in
the shack. I know mine didn't. I was putting nearly 700 watts into the
antenna and you could touch the amp chassis without any RF burns. Didn't
have the fancy tools I have now for testing things, but still managed a
good, clean and loud CW signal from an angled dipole. Worked a lot of DX
on 75 with that antenna, including a nightly sked with Midway Is. for
traffic (from Vancouver, BC.).


--
Dave Oldridge+
ICQ 1800667

 

Yeah, i had the same prob with an old smd LS244 octal, replaced it with a
74HCT244 octal and now the bloody unit doesn't work whatsoever.....oh well,
back to trying to find an original.....
Gaz