HARC TEK NET

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Subjects that have already been discussed will be displayed in GREEN text to show it has been archived.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”

  • Homebrew projects

  • 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

#1DSCN1955

#2Antenna switch

 

#3DSCN1956

 

#4Antenna switch Encoder

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.

#5DSCN1959

 

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.

 

 

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  • Homebrew projects

#1 

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 enclosureDSCN1930

 

#3

AntennaRelays

#3ADSCN1928

 

#4 Ready to wire upDSCN1939

 

#5 Relay Wiring20191006_174446_Film3

 

 

#6 DTMF Touch-tone Decoder ReceiverMT8870

 

 

 

#6A DTMF Decoder  Digit #1

DSCN1932

#6B  DTMF Decoder  Digit #2

DSCN1933

 

#6C  DTMF Decoder Digit #3

DSCN1934

 

#6D  DTMF Decoder receiving any other digitDSCN1931

 

#7 DTMF Encoder CircuitEncoder

 

#7A DTMF Encoder BoardIMG0186A[1]

 

#8 DC power/ Audio Injector circuit20191006_174646_Film3

 

Finished project pictures may be available at the beginning of next weeks TekNet as a recap from the previous week’s discussion.

 

https://www.facebook.com/pg/HARC-Technical-net-chat-104477997564655/posts/?ref=page_internal

.

 

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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…Loss visualization.

 

#3 Where to put the antenna

aNTENNA_pLACEMENT

#4 Propagation between a 1/4 wave and 5/8 wave gainGain_plot_70cm_vehicle

Notice the plot at approximately 28 degrees.

 

#5 Beam Width

untitled

 

#6 Feedline losses

240-abr

 

 

#7 Antenna Types

page63

#7A

oshinvoy-uv-dual-band-mobile-radio-brackets-whip-antenna-145-435m-dual-band-car-two-way-radio-whip-antenna

 

 

#8

UT108UV-dual-band-antenna-with-SMA-plug.jpg_350x350

 

#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.

 

 

 

 

 

 

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Sept 22, 2019

“What does the Touch-tone buttons on your HT do?”

#1  Frequencies

DTMF-Keypad-Layout

 

#1A  Single Tone & Dual Tone

dowsingle tonedymf wave

 

#2  Examples – Encodersty__90555.1522962981.1280.1280

40552627

TelcoPad

#3 Encoder ICs2559_5089freqs

 

#4 TelcoEncoder Schematic

ttpad

 

#5 DTMF Decoders – Telco KT-247B247b

#5A DTMF Decoder – Telco  LC  type

Decoder

#5B Decoder MT8870 type

MT8870

#6 Decoder Schematic – MT8870 ICimages

 

 

 

 

 

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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.

 

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Sept 8, 2019

Building a disguised UHF base antenna

#120180827_222958_Film1

 

#2Looped J-pole antenna

 

#3Bending Chart

 

#4Pigtail

 

#5A    Prepping the piecesEnd cap

#5BT pieces

#6 Anchoring the antennaInside T

 

 

#7 Mounting to a vertical supportBottom

#8 Mounting hanging from a tree or overhead supportBottom2.jpg

 

#9Final

 

#10

AA7AU_Sweep

#11  Dual band ground plane

cheap_dualband_gp2

 

 


Sept 1, 2019

General question/ answer discussion and swap meet listing

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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.

images

#2 Display driver circuit LED

cb4c3562d9e957dcac7bebb78a9139a6

 

 

#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.

images (1)

#4

The DArsonval 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.

NV_1017_Mulreany_Figure01

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.

 

#6

 AA_Battery_analog

 

#7

AA_battery_digital

#7A

AA_digital_reverse

#7BAnalog_switched_leads

#7C

Power Supply output

 

 

#8 Measuring vehicle alternator output

Vehicle battery

#9 Measuring Resistance

DSCN1895

#9ADSCN1896

#9B

Analog5K

#9C

!K_resistor

 

 

#10 Measuring current demand

LED current

#11 Measuring current with leads reversed

DSCN1902

 

 

#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

#1Allstar_Block

#220190817_181727_Film3[1]

#320181005_013551_Film4

Allstar node located at Pleasants Pk., California WB6MIE repeater 446.120MHz

#4ra40-top

#5RA40_sche

#620190808_113100_Film3

#7Reg_sche

#8

Hardware improvements from the Pi 3 to Pi 3 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

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August 11, 2019 

Astron analog power supply

41ALFXIVSuL._SX425_

images

post-229636-0-28854900-1522755573

rs20-1988-09-24

Astron4

ps2PS3

 

PS4

#5 Adjustable regulator board

20190808_113100_Film3

#6 & #7 Surplus equipment

Lambda-LXS-C-5-OV-Chassis-Mount-Regulated-Power-Supply-Input-105-132V-57-63Hz-Used-18325340956711775881