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On 8/10/22 18:32, John wrote:

What the heck kind of ruler is that!?

John

A slide rule.

It's been nearly 40 years since I used one. Not sure I still remember how...

73

Stan
KM4HQE

Nice find!!!

Cheers,
Lyle
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On Wed, 10 Aug 2022 14:54:56 -0700
"Martin Glazer" <mglazer2014@...> wrote:

--
73 NM6Y
Bickley Consulting West


"Black holes are where God is dividing by zero"


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73? ?NM6Y
Bickley Consulting West Inc.


"Black holes are where God is dividing by zero"

The kind that designed the Mercury, Gemini, and Apollo Spacecraft!

What the heck kind of ruler is that!?

John

nice

On Wed, Aug 10, 2022 at 3:26 PM Dave W6OQ via groups.io <david.hostetler=
[email protected]> wrote:

I have a well maintained bamboo slide rule in a drawer somewhere here.
Never liked the metal ones. It got me through college to a BSEE, but
shortly after that, on my first full time engineering job at a small
company, the manager bought us one of the new HP pocket calculators to
share, then he added to the collection with newer models every year. Within
five years, I was able to purchase my own. Yes, it and a few other HP
calculators are around here somewhere as well.

K&E 4138? Log/Log Deci-trig?

I have a well maintained bamboo slide rule in a drawer somewhere here. Never liked the metal ones. It got me through college to a BSEE, but shortly after that, on my first full time engineering job at a small company, the manager bought us one of the new HP pocket calculators to share, then he added to the collection with newer models every year. Within five years, I was able to purchase my own. Yes, it and a few other HP calculators are around here somewhere as well.

Lucky you!!!!!

Remember, during the Manhattan Project at Los Alamos, the Slide Rule "made"
the first U and Pu supercritical masses happen. Trinity (New Mexico)
proved their worth.

I need to shop our local shops for just such a piece of nostalgia.

Dave - W?LEV

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Dave - W?LEV

In addition to my last post, SWR / VSWR can be measured using either
voltage or current. If there is SWR / VSWR on the line, both will change
according to Ohm's Law. At any given point referenced other points along
the line, voltage goes up and current goes down and the voltage decreases
and the current increases - all keeping the power the same anywhere along
the line. The power measured anywhere along the line will remain constant
(neglecting losses) since, for a sine wave, power = voltage X current.

Dave - W?LEV

On Wed, Aug 10, 2022 at 9:58 PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:

QUOTE: " So, you are saying that VSWR is based on voltage, but caused by
an impedance mismatch."

IF: Z(Source) = Z(XMSN Line) = Z(Load) There will be no standing waves
and the SWR / VSWR will measure 1:1.

If any of the three above individually move from the appropriate Z, there
will be standing waves and the SWR / VSWR will measure something other than
1:1.

If all of the three above coincidently move together to the identical Z's,
there will be no standing waves and the SWR / VSWR will measure 1:1.

Dave - W?LEV

On Wed, Aug 10, 2022 at 4:30 PM Russ <u.rusty@...> wrote:

On Wed, Aug 3, 2022 at 09:10 AM, Kenneth Hendrickson wrote:

If the load is not perfectly matched to the source, there will be a

voltage

standing wave ratio (VSWR) because of the mismatch.

So, you are saying that VSWR is based on voltage, but caused by an
impedance mismatch.

--
*Dave - W?LEV*
*Just Let Darwin Work*


--
Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*


--
Dave - W?LEV

QUOTE: " So, you are saying that VSWR is based on voltage, but caused by
an impedance mismatch."

IF: Z(Source) = Z(XMSN Line) = Z(Load) There will be no standing waves
and the SWR / VSWR will measure 1:1.

If any of the three above individually move from the appropriate Z, there
will be standing waves and the SWR / VSWR will measure something other than
1:1.

If all of the three above coincidently move together to the identical Z's,
there will be no standing waves and the SWR / VSWR will measure 1:1.

Dave - W?LEV

--
Dave - W?LEV

Thankyou Kent, from someone who can still use a Leacher Line :-) 73 de GK8NXD

OK, for the youngsters in the group a bit of history.
It's over 100 years ago.Coax has not been invented yet.There are no SWR metersThere are no VNA's.? ?(Well, an RF Bridge and a lot of math will get much the same answer)
So you would walk along the parallel transmission lines between the transmitter and the antenna with a voltmeter.
At one point along the line you measured 50 volts, at another point you measured 25 volts.
Voltage Standing Wave Ratio is 50/25? or 2
These peak and nulls were waves of voltage that pretty much stayed in the same place, thus were called? "Standing Waves"
If at some point you got a ZERO voltage, this usually happened when there was an open or a short in the system, then.
VSWR was 50/0 and was just called "Infinite"
Now if you walked along the line and got 50 - 50 - 50 - 50 - 50
Then VSWR was 50/50 or 1And they liked to say the SWR was "FLAT"
Hope this helps, Kent
For the other old farts in the group, yep, still have a slotted line in the back garage.? Think I still know how to use it, but the HP-8510C does such a better job. hihi? ? Oh yea, the Nano's do a pretty good job and weight 200 lbs less!

On Wed, Aug 3, 2022 at 09:10 AM, Kenneth Hendrickson wrote:

If the load is not perfectly matched to the source, there will be a voltage
standing wave ratio (VSWR) because of the mismatch.

On Wednesday, August 10, 2022, 12:30:34 PM EDT, Russ <u.rusty@...> wrote:

So, you are saying that VSWR is based on voltage, but caused by an impedance mismatch.

VSWR is a *MEASURED* voltage difference along the transmission line. Yes.

On Tue, Aug 9, 2022 at 09:58 PM, F1AMM wrote:

H4_REV4_3.pdf

Would you have the same for my nanovna-F I don't understand anything in github
to treat this myself.
--

The NanoVNA-F is not an open source design. The manufacturer does not publish schematics or source code for this product.

Roger

VSWR
Voltage Standing Wave Ratio

The cause is the impedance mismatch.
The measurement is in volts.???

Kent

On Wed, Aug 3, 2022 at 09:10 AM, Kenneth Hendrickson wrote:

If the load is not perfectly matched to the source, there will be a voltage
standing wave ratio (VSWR) because of the mismatch.

So, you are saying that VSWR is based on voltage, but caused by an impedance mismatch.

Resonance has no effect on antenna performance so it’s not
a concern if an antenna is resonant or not. I don’t think I ever saw an US AM broadcast
antenna that was resonant.

It's not just US broadcasting stations that are like that, in France too. I did part of my out-of-school internship at a station that was broadcasting

300 kW on 600 kHz
150kW on 890kHz

All in AM, modulated screen plate so x4 for PEP.

The antenna was a 40 m high radiating tower, guyed, supported by a large insulator. Each of the two transmitters came via a 135 Ω pseudo coaxial (in wires) to a small cabin where there was a plug at each frequency which served as a duplexer and a series choke to compensate for the residual capacitance. The pylon was far from the ? wave

When we study an antenna project on EZNEC, we can clearly see that the resonance only acts on the impedance and quay only on the reactive. The real part of the impedance varies little in the vicinity of the resonance
--
F1AMM (Fran?ois)

-----Message d'origine-----

De la part de Ray
mercredi 10 ao?t 2022 16:40

You are all missing the message, Resonance has no effect on antenna performance so it’s not a concern if an antenna is resonant or not. I don’t think I ever saw an US AM broadcast antenna that was resonant.
Ray
W8LYj

What one wants to avoid (with some transmitters) is too much reactive
component - sure, you can cancel it with a passive component, but that
component will have some loss AND the required value changes with frequency.

I thought, at one time, that by not using the antenna at resonance (zero reactive) the bandwidth of the antenna would be widened. After adaptation (filter in 'L'), I note, by calculation, that it is not so.

Can you confirm this statement for me ? (or not)
--
F1AMM (Fran?ois)

-----Message d'origine-----

De la part de Jim Lux
Mercredi 10 ao?t 2022 01:29