Next HARC TEK NET will be…..
October 27th at 8pm
Adding a Ham Radio voice to your vehicle’s alarm system.
Our next “ASK THE PROS” Tek Net will be on November 10th.
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WELCOME all to the Henderson Amateur Radio Club’s TEK NET
This is a new adventure and is open to everyone’s suggestions and ideas. The more discussions and comments the better. There are many hams with years of hands-on experience to share and many without that knowledge who wants to gain a better understanding of some of the many facets of amateur radio, communications or electronics.
Subjects that have already been discussed will be displayed in GREEN text to show it has been archived. Those will be at the bottom of the current discussion listed by date, for easy reference should anyone have a question concerning previous subjects.
We will have a round table type of QSO on all of the linked HARC repeaters. A roll will be established for that evenings net, for record keeping purposes.
After each photo, diagram or comment, I will ask for anyone’s comment or question.
The photos, drawings and diagrams found here will assist with visually understanding the subject for that net discussion.
The subject for the next net will be listed as soon as it’s available (typically Saturday afternoon the day before ) so you can look over the net’s topic for the upcoming Tek Net come Sunday night.
Participation is what will make this a success.
Send me your ideas for subject discussion
Subjects for discussion: (No particular order)
* Aug 11, 2019 – Power supplies- operation and failures – analog type
Sept 1, 2019 – General question/ answer session & Swap meet listings
Power supplies- operation and failures – switching types
Grounding around the shack
Sept 15, 2019 – “ASK THE PROS”
What is D-star
Stealth or disquise antennas in an HOA
Sept 22, 2019 – What does the Touch-tone buttons on your HT do?
Aug 18, 2019 – How does Allstar work
Using commercial radios on Ham frequencies
Ham swap meets, do you go?
Sept 29, 2019 – Mounting mobile antennas for better performance
Have you ever built or owned a repeater
What do you think of the audio on most repeaters
What does it take to have a successful repeater
Building your own antennas
Sept 8, 2019 – Building a UHF disguise base antenna
Aug 25, 2019 – How to use a multimeter
What does a swr meter really tell you
What do we know about Hoover dam power plant
Why should I turn my radio on other than for nets
Do you have or know about Solar power
Since being licensed, how have you seen amateur radio change
Next Tek Net will be about….
DTMF Remote Antenna Switch Project conclusion
The optional circuit shown is to indicate that a dtmf tone is being sent to the remote unit.
This is accomplished by using the MUTE output function of the encoder ic.
Tests have been made with 100 feet of RG6 cable TV coax, the unit switched antennas like it was suppose to. The photo is showing a 25ft RCA to RCA cable video cable for testing purposes.
The MT8870 DTMF Decoders are available online or from me for $4.00 each. The CD 4028 Cmos IC is available to anyone wanting to pick it up from my QTH at no charge.
The DTMF Encoder Ic is manufactured by AMI and is available from several vendors online.
The DTMF Encoder doesn’t have to be an S2559, there many different Touch-tone encoder IC’s out there ( example – TP 5089 $4.95 each), anything that will generate the touch-tones needed will work.
This weeks project is a remote controlled antenna switch.
This remote switch became a project after talking about DTMF signalling a couple of weeks ago.
One aspect of this switch is that we will power the remote relays and switch those relays using just RG-6 cable TV coax. DC power as well as the audio DTMF tones will be sent up the center conductor eliminating multiple conductors.
#2 Preparing the RF enclosure
#4 Ready to wire up
#5 Relay Wiring
#6 DTMF Touch-tone Decoder Receiver
#6A DTMF Decoder Digit #1
#6B DTMF Decoder Digit #2
#6C DTMF Decoder Digit #3
#6D DTMF Decoder receiving any other digit
#7 DTMF Encoder Circuit
#7A DTMF Encoder Board
#8 DC power/ Audio Injector circuit
Finished project pictures may be available at the beginning of next weeks TekNet as a recap from the previous week’s discussion.
Sept 29, 2019
Mounting mobile antennas for better performance
#1 The DB…
When we talk about a db rating, what is really being expressed?
dB is an abbreviation for “decibel“. One decibel is one tenth of a Bel, named for Alexander Graham Bell. The measurement quoted in dB describes the ratio (10 log power difference, 20 log voltage difference, etc.) between the quantity of two levels, the level being measured and a reference.
From a loss standpoint, if a measurement is deemed to be -3db between to levels, then that indicates a measurement of 1/2 or 50% lower signal level.
(You will see this described when looking at antenna feedline losses at a certain frequency limit on lengths of 100 ft or more).
A measurement level of +6db would indicate a signal level approximately 4 times the originating signal level on the reference antenna.
NOTE – It has stated that the energy level losses from an HT inside of a vehicle is at times -11.3db or greater than the same signal level radiating from a center mounted 1/4 wave whip in the center of the vehicle’s roof.
That means that a 5 watt HT will be radiating a signal approximately equal to .3125 watts out of the vehicle. (Conditions in the car vary)
#2 Some examples…
#3 Where to put the antenna
#4 Propagation between a 1/4 wave and 5/8 wave gain
Notice the plot at approximately 28 degrees.
#5 Beam Width
#6 Feedline losses
#7 Antenna Types
#9 Drilling a hole in my car will reduce the value.
As the manager of a Motorola Mobile Telephone Service shop in San Diego, Ca., I was asked that question very often by customers having mobile telephone antennas installed on their new vehicles.
Over the years I have questioned car dealerships, if a vehicle had a mobile telephone antenna (it was easier for them to understand why there was antenna on the vehicle) installed, would that affect the vehicle’s resale value when it was removed and a proper rubber flat antenna plug used to cover the hole.
My answer from the Mercedes, BMW, Chevrolet and Ford dealerships in San Diego, Ca. at the time all responded with no.
So….is it worth the trouble to install an antenna properly…absolutely.
Will it cost me money down the road….absolutely not (if removed and plugged properly).
Will it make a difference in performance, again… absolutely!
Antenna mounting holes can be as small as 3/8″ to 3/4″, all have plugs available.
CONCLUSION – Put a charge on that cordless drill and get ready to make your mobile radio talk and receive better than it ever has.
Our next “ASK THE PROS” Tek Net will be on October 13th.
Have your questions ready and plan to be there.
Sept 22, 2019
“What does the Touch-tone buttons on your HT do?”
#1A Single Tone & Dual Tone
#2 Examples – Encoders
#3 Encoder IC
#4 TelcoEncoder Schematic
#5 DTMF Decoders – Telco KT-247B
#5A DTMF Decoder – Telco LC type
#5B Decoder MT8870 type
#6 Decoder Schematic – MT8870 IC
Sept 15, 2019
“ASK THE PROS” Session for tonight.
Our distinguished panel of experts for tonight’s free form open forum has many years of practical experience in their respective fields and are still active today.
Subject matter can be about Ham Radio, Electronics, Audio, Video, Space Communications to some Nuclear Physics.
If we don’t have the answer for you it will be researched and the answer will be posted here.
Questions will be entered here along with their answers.
Tonight’s panel participants are….
WB6MIE – TONY DINKEL RF, HAM RADIO, AUDIO & MORE
NO7BS – KIRK NEMZER ANTIQUE RADIO RESTORATION, HAM RADIO, SATELLITE VIDEO & MORE
KG7QWH – SHANE HUSTON PROFESSIONAL IT SUPPORT
WB6AMT – EARL LIZARDI HOMEBREW BUILDING, COMMUNICATIONS
Be sure to state who you are directing your question to, so they can respond directly to you.
Sept 8, 2019
Building a disguised UHF base antenna
#5A Prepping the pieces
#6 Anchoring the antenna
#7 Mounting to a vertical support
#8 Mounting hanging from a tree or overhead support
#11 Dual band ground plane
Sept 1, 2019
General question/ answer discussion and swap meet listing
August 25, 2019
How to use a multimeter
#1 Digital LCD or LED multimeter
Some LCD digital meters have a sensitivity of Megohms per volt, making them very attractive when measuring a high impedence circuit, because it won’t load down the circuit or measurement under test.
#2 Display driver circuit LED
#3 Analog Multimeter
Quality meter movements sensitivity was 20,000 ohms per volt, which depending on the circuit would change the tuning or measurement by loading the circuit down.
To a circuit it could look like you just connected a 20K resistor in the circuit.
The D‘Arsonval movement is a DC moving coil-type movement in which an electromagnetic core is suspended between the poles of a permanent magnet. This was first called a galvanometer before the development of the D Arsenval movement. They were the first instruments used to detect and measure small amounts of electric currents.
Note…that when using an analog meter the Polarity or Positive and Negative leads MUST be hooked up correctly or the meter movement will deflect the needle in the opposite direction and can damage the movement.
#5 What are some of the uses of a typical multimeter?
* DC voltages when checking a battery or power supply output.
* Checking the charging voltage that your car’s alternator produces.
* Checking the AC voltage at an outlet in your home.
* Determining what AC voltages an unmarked transformer is producing.
* Measuring the ohms of a resistor or potentiometer.
* Checking the voice coils of a speaker.
* Checking a fuse or lamp to see if it is open.
* Measuring the current that a circuit is drawing from its power source.
* Measuring the charging current to a battery being charged.
* Use as a continuity checker with an audible tone.
#8 Measuring vehicle alternator output
#9 Measuring Resistance
#10 Measuring current demand
#11 Measuring current with leads reversed
#12 Continuity testing (low resistance range)
Used to track a short.
Check for good ground.
For checking fuses that are sand filled.
Checking connections or solder joints that look suspicious.
August 18th at 8pm –
How does Allstar work
Allstar node located at Pleasants Pk., California WB6MIE repeater 446.120MHz
What is the difference between Raspberry Pi 3 and B+?
The Pi 3 Model B+ is based on the same quad-core, 64-bit processor, as the Pi 3Model B. Like the Model B, the B+’s is based on a Arm Cortex A53 architecture. However, the B+ ups the speed of the CPU to 1.4GHz from 1.2GHz in the original Model B, an increase of 16.7%.Mar 14, 2018
August 11, 2019
Astron analog power supply
#5 Adjustable regulator board
#6 & #7 Surplus equipment