Category: Field Deployment

HAMsmithing July 2017

This is a DIY USB charging cable for my Kenwood TH-F6A/F7E handheld radio.

web-IGP3869It is the same concept like the Baofeng USB to 10V charging cables that are found on eBay and amazon. But the virtue of the Kenwood HT is that it accepts a wide array of operating and charging voltage. Plugged to a 12V source it both charges and operates.

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Introduction to Surecom SR-112 Simplex Repeater Controller

The Simplex Repeater Controller Principle

The Surecom SR-112 Simplex Repeater Controller is a device that allows you to setup a “field” or “emergency” simplex repeater. In other words it is -and as we call it locally- a Parrot. It records and replays what it hears from the radio it is connected to.

So what the user has to do, is define the simplex repeater frequency, set it on the radio and connect the radio to a Simplex Repeater Controller by a purpose made/bought cable. The device will start repeating what the user will speak on the radio.

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It is a dead simple, easy and economical way to set up a repeater and cover dead ground, but it does have its shortcoming. While simple technically, it is a bit complicated operationally. It requires all involved parties to expect a repetition of what they are hearing.

Let’s assume that a Simplex repeater is placed on the top of a ridge to cover its two sides. The caller will input the message on the repeater and another user on the other side will hear the repetition. but what if there is a third user on this side of the ridge, within range of the caller? It will hear the message twice! And if not advised Not to, he will probably try to respond on the call, disturbing the repetition….

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More Easy Antennas for the VHF/UHF

For the purposes of the next Radio Communications Seminar I constructed 2 antennas.

The first one is a ground plane field antenna using a folding handheld radio antenna.

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An SMA to chassis mount adapter is used and the radials are just solid core wire twisted through the adapter mount holes. The good thing about this method is that the antenna requires no tuning as the vertical element is already pretuned.

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The Ultrapack Battery Pack for QRP Low Power Radios

Survival Tech Nord has an open project running for making a small external battery bank for radios that operate at low output (5+ watt).

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The basic principle is using 18650 lithium-ion (Li-Co or Li-Mn) batteries that have big energy density and match their voltage to that of the radio.

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One more DIY Groundplane Field Antenna version

Bret at the SurvivalComms Youtube channel (it is not me, just a name coincidence I did not expect) has built his own version of the Jungle Antenna (Link 1, Link 2)

He uses a ring made from ABS rods to “hang” and position the ground wires, and the handheld’s radio own antenna. From the looks of it performance can further be increased with a telescopic antenna like the Diamond RH-770.

He also has a build of a discone antenna with the same method.

DIY folding VHF / UHF Discone Antenna

Check him out!

 

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The Standardized Prepper Coded Matrix

In 2012 the Catastrophe Network published what they called The Standardized Prepper Coded Matrix (SPCM). The Catastrophe Network is no more, but luck has it that I kept the SPCM in my archive.

TCNScreen Capture of the Original Post.

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Easy DIY VHF Antennas with the BNC Male to Banana Jack Connector

In this short piece I will exploring the uses of the BNC Male to Banana Jack Connector in VHF antenna building.

It is a very controversial item cos it allows easy connection of the antenna elements, has a build-in coax connector, is stout enough for field work, and has also 2 mounting holes to pass your wire or paracord through. Practically you can build anything with it as long as you can cut and strip some wire.

Unfortunately I am too  occupied with lesser stuff to make and tune the actual antennas, so please make do with their simulations and a few comments.

The Vertical Dipole

Dipole

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