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M0MTJ  |  Operating Conditions  |  Antennas / Aerials  |  /P Portable Operating  |  Accessories  |  Projects & Kits  | Useful Information
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Polarised Power Connectors

Perhaps the most important item is one that helps protect expensive equipment against costly reversed polarity mistakes.

Anderson PowerPoles will take care of the polarity of power leads when making connections to batteries and power supplies. Using Anderson PowerPoles guards against making a simple rushed mistake that would otherwise be VERY costly indeed!

30 Amp Anderson PowerPole connections are excellent for use in amateur radio.
Anderson Powerpoles - modular polarised
                          power terminals
Anderson Powerpoles - modular polarised power terminals
G0HWC has some excellent information here:  http://www.g0hwc.com/anderson-powerpole.html
Manufacturer website: http://www.andersonpower.com/products/singlepole-connectors.html

UK Supplier: UK Supplier:  Torberry Connectors, 34a Aston Road, Waterlooville, Hampshire.  PO7 7XQ

Antenna Tuning Unit

Or more correctly described as the Antenna Matching Unit - since an ATU cannot tune an antenna, it can only match the impedance presented by the antenna system to the 50 ohm impedance required by the transceiver or receiver.

                          945E Antenna Matching Unit - front
Front panel of my MFJ Antenna Matching Unit

MFJ 945E Antenna Matching Unit - rear
Rear panel of the MFJ Antenna Matching Unit

LDG Z-11 Pro
The front panel of my LDG Z-11 Pro

LDG Z-11 Pro
The rear panel of the LDG Z-11 Pro

The LDG Z-11 Pro is a real revelation that saves so much time. The fact that is has 8000 automatic internal memories (2000 for each of four aerials) means that once memorized the Z-11 Pro will return to the LC setting for a particular aerial and frequency combination literally in the blink of an eye. A true 'magic box' of tricks - well relays, inductors and capacitors actually!  http://www.ldgelectronics.com

Antenna Analyser

I have found the antenna analyser to be an invaluable piece of equipment.

It is extremely useful for checking and setting up external aerials since it save one having to keep running up and down stairs to the shack checking VSWR. With an antenna analyser it is possible to remain by the antenna while making adjustments and checking.

The analyser can also be used to diagnose faults and to assist in making many other extremely complex measurements and calculations.

Perhaps it is at its most valuable in everyday use when 'tuning up' before transmitting. Because an analyser has an internal and adjustable oscillator, it can be used to check VSWR at and make ATU adjustments without having to press the PTT on the radio. This prevents any unnecessary interference to other radio operators. Essential!

                          259B / Z Antenna Analyzer
MFJ 259B Antenna Analyser

To quote from MFJ Enterprises; "Read antenna SWR and Complex Impedance 1.8 to 170MHz. Read Complex Impedance as series resistance and reactance (R+jX) or as magnitude (Z) and phase (degrees). You can determine velocity factor, coax cable loss in dB, length of coax and distance to a short or open in feet. You can read SWR, return loss and reflection coefficient at any frequency simultaneously at a single glance. Also read inductance in UH and capacitance in pF at RF frequencies. Large easy-to-read two line LCD screen clearly displays your information. Built-in frequency counter, Ni-Cad charger circuit, battery saver, low battery warning and smooth re-duction drive tuning and much more. Super easy to use! Just set the band switch and tune the dial -- just like you transceiver. SWR and Complex Impedance are displayed instantly!"

Noise Bridge - a much lower cost alternative to an expensive antenna analyser

Antenna analysers now tend to be extremely expensive, but a good noise bridge could be used as a much lower cost alternative. A noise bridge can be used for measuring the impedance of antennas and traps at various frequencies. Your H.F receiver is used as the bridge
null detector.

A number a circuits are available on the internet and kits are also available, such as the high quality RX2 from VK3AQZ Kits. Here are some useful links:


One of the most useful devices for the shack is a balun, or more to use a more correct term, a 1:1 choke balun. This will match a balance 75 ohm twin feeder to the unbalanced 50 ohm input of the Antenna Matching Unit.  The Antenna Matching Unit (often referred to as an ATU) will then transform the impedance presented by the antenna feeder to the 50 ohms required by the transceiver.

M0MTJ Home Brew 4:1 Balun
M0MTJ Home Brew 4:1 Balun

Dummy Load

A dummy Load is an essential item of amateur radio equipment. It allows various tests to be carried out on the transmitter, such as checking modulation or deviation levels, without radiating an RF signal from the antenna. This avoids causing unnecessary interference to other users.
MFJ 260C 300 Watt Dummy Load
MFJ 260C 300 Watt Dummy Load

Meters for testing electronic and electrical circuits:

AVO Model 9 Meter :

I am the (rather proud) owner of an AVO Model 9 multimeter. AVO meters were probably the defacto standard many government agencies, Post Office telephone engineers, military / NATO as well as civilian markets such as television repair technicians.

The Model 9 AVO is very similar to the well known (classic) Model 8 AVO, except that it was originally designed, in the late 1960's, more specifically for electronics engineers and an export market
; as such it uses international (ISO) symbols rather than printed words or letters that identify the controls of the Model 8. The adjustments are 1 - 3 - 10 rather than 1 - 2½ - 10 that are used on the Model 8, otherwise the Model 9 and Model 8 are the same. It has a beautiful large clear scale, about  5 inches (12.5 cm) long, with a silky movement and knife edge pointer with parallax mirror and a high sensitivity of around 20,000 ohms per volt which I was told is higher than some Model 8's. AVO meters should be used lying down with the dial facing upwards to ensure proper accuracy.

The scale of a good analogue, swinging needle, meter is often much easier to read than the often changing digits of a digital multimeter, so it's probably important to have both types available for different situations. - So keep your eyes peeled for a nice Model 8 or Model 9 on your travels, not only will it look nice it could well be an invaluable measurement tool!

AVO Model 9 multimeter
AVO Model 9 multimeter

Digital Multi-Meter - DMM :

Handy, lightweight and versatile, with many measurement functions such as transistor tester, capacitance and inductance metering - a Digital Multi-Meter:
Digital Multimeter
Digital Multimeter

Power Supply Unit

Perhaps an obvious requirement! The PSU is needed for powering a transceiver that has no built in mains transformer and for powering other station accessories. The PSU needs to be able to provide a clean and stabilized 13.8 volt supply at the necessary current rating: A typical 100 watt transceiver would require around 20 Amps when running at full power.

I use a Palstar PS-30 PSU (also known as EP925 and sold under various brand names), it has short circuit protection and has an over-current warning indicator, a galvanised steel case, precision ammeter and voltmeter monitoring, thermostatically controlled fan that cuts in when the temperature reaches 70 degrees. Terminals are binding posts and snap in terminals. View User Manual. 

I cannot recommend this unit, it's rather cheap and nasty, the fan can be noisy ( I have replaced mine) and the circuit is not the best. It does not have Over Voltage Protection; This is dangerous since supplying a radio with over 16 volts can damage it, possibly beyond repair - so a power supply that omits Over Voltage Protection is inexcusable. I will be fitting an over voltage 'Crowbar' protection system as soon as possible. PR0FRI has a web page of modifications for this PSU, noted below:

Palstar PS-30 PSU
Palstar PS-30 25 amp (30 amp peak) PSU  (a.k.a.Manson EP-925)

See The USER MANUAL Here >

R.F. Filter - Low Pass Filter

An RF filter may not always be necessary, but if the transceiver suffers any spurious harmonic output when transmitting an external filter can filter such products out, thereby preventing or reducing any possible interference to receivers operating on higher frequencies, such as televisions and domestic radios etc.

External Loudspeaker

An external speaker is often better than the loudspeaker built into many radios. An external speaker also allows the use of external audio filters or digital signal processing units (DSP's) to be connected to the transceiver.

One speaker is large in a 'home brew' cabinet containing a very high efficiency GL13 10 watt, 6 inch loudspeaker unit. The drive unit and grill were purchased from Maplin. I find it very good in most circumstances.

Another 'home brew' speaker is shown below. This includes a switchable low pass filter that can help cut down hiss and noise on weak signals. This is constructed using an efficient elliptical loudspeaker housed in an MB5 ABS enclosure. This is convenient size for mobile use. Read more here >

Extension Speaker with Low Pass Noise
                              Filter by M0MTJ
A small home brew speaker using an efficient elliptical drive unit.
This speaker also includes a switchable low-pass filter.

Read more here >

10 watt 6 inch Maplin
                          GL13 loudspeaker
My larger speaker, constructed using a Maplin GL13
6 inch 10 watt drive unit plus grille


Useful for personal listening so as not to disturb other people too much. Headphones may also be helpful when trying to hear weak signals. 'Closed-back' headphones cut out more external noise than 'open-back' headphones.

Alternative Microphone

As an alternative to the hand mic that is supplied with the Kenwood TS-590, I use a separate dynamic microphone mounted on a goose-neck, PTT operation is by foot switch. Read more here >

The HM-103 hand mic that comes with my Icom IC706-mk2G seems very good, but I also have a Leson TW-232 Desk Mic available.

Morse Key for CW

This is my simple HK-705 Hi-Mound straight Morse key.  (Still haven't mastered Morse yet!  :-(  )

HK-705 Morse

Power Meter / SWR Bridge

Power Meter
Standard type power and SWR meter

Power Meter
Cross Needle type power meter

Guying Antenna Masts and Poles - Clam Cleats "Line-Lok"

Excellent for guy ropes and for binding one pole to another with rope.

Line-Lok guy runners from
Line-Lok guy runners from
Line-Lok guy runners from ClamCleats  -  fantastic for guying antenna masts quickly and successfully.
http://www.cleats.co.uk                                          http://www.clamcleat.com

Noise Reduction / Digital Signal Processor

For radios without any internal Digital Signal Processing and external DSP unit could be very welcome. The BHI NEIM 1031 Noise Eliminating Module has an adjustable DSP level. Even without using the DSP noise reduction the BHI unit has a built in 4.5 KHz low pass filter that can make harsh audio sound much more pleasant.

BHI NEIM 1031 dsp module
BHI NEIM 1031 dsp module

Personal Computer

A personal computer might not be regarded as an accessory as such, but it an essential tool. I use the PC for all the usual things such as researching amateur radio subjects on the internet, but it can also be used for decoding and sending data modes, e.g. CW (Morse), Packet,  PSK31, RTTY, SSTV and keeping a station log book.

Data modes>


The obvious tools are soldering iron, pliers, screwdrivers, wire strippers, screw drivers and watch makers screwdrivers, tweezers, spanners and a good multimeter. Here are a few more ideas that will prove useful:

Measuring Caliper

Measuring calipers can be of the vernier style or digital variety, shown below. A caliper is extremely useful for measuring the diameter of wire, tubes and poles and any other item that is difficult to measure with a ruler or tape measure.

Digital Measuring Caliper
Digital Measuring Caliper

Glue Gun

I only recently aquired a glue gun, and what a superb aquisition it is. Very useful for fixing all manner of things, but particularly useful for sealing and fixing cable entries and securing wires and cables in electronic projects - an almost endless list. There are several different brads of glue gun, but mine is made by Stanley.
Stanley Glue Gun
Glue Gun - this one is made by Stanley Tools

Helping Hands

Having just two hands is rarely enough when constructing small projects, this is where some extra Helping Hands are invaluable!
Helping Hands
Helping Hands

Nylon Hose Clamps / Clips

Nylon Hose Clamps - Nylon
Nylon Hose Clamps - Nylon Clips
Reusable Nylon Hose Clip / Reusable Circular Clamps
Useful for securing telescopic fibreglass poles - e.g. holding each
section in place in windy weather or to use as a guying ring (spider)
(Kaf-flex Nylon Clamps) (Herbie Clips)

                                      DataLink" data interface with
                                      USB soundcard from G4ZLP
"Digimaster DataLink" data interface
with USB soundcard from G4ZLP

                                      MiniPRO" data interface from
"Digimaster MiniPRO" data interface from G4ZLP
- uses PC's sound card

"Digimaster Pro
                                      PLUS" data interface from
                                      G4ZLP - uses PC's sound card
"Digimaster Pro PLUS" data interface
from G4ZLP - uses PC's sound card

G4ZLP DigiMaster USB
G4ZLP DigiMaster USB CT17-CT62
for rig control
G4ZLP USB Dongle
G4ZLP USB Dongle
for rig control

http://www.g4zlp.co.uk/unified/IcomCAT.shtml http://www.g4zlp.co.uk/unified/YaesuCAT.shtml

                                Whip Antenna Products

Icom amateur radio

Mike Smith - MDS975.co.uk © 2003 - 2016


Amateur Radio; Ham Radio; Radio; Transceivers; HF; VHF; UHF; Data Modes; Morse Code; RTTY; PSK31; SSTV; FSTV; Amtor; Sitor
Antennas; Aerials; Cable; Coaxial Cable; Twin Lead; Masts; Poles; Propagation; Computer; PC; USB Computer Interface; Microphone
Loudspeaker; Filters; Noise Reduction; DSP; Digital Signal Processing; Morse Key; SWR ; Inverted L; Inverted V; Dipole; Doublet;