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STATION ACCESSORIES


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.




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.

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!

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:






Balun

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.

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.






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



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:






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 >




Headphones

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.




Power Meter / SWR Bridge


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

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


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.

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