My Shack
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LAST UPDATED: 1st January 2018

Welcome to my radio shack! This is the room (or rather part of a room) where all the radio gear is located.  Due to space limitations at the QTH, I have had to become inventive with both the location and the content of my radio shack. Originally, it was located in our bedroom, which is obviously not the best place (especially for late night/early morning DXing). I am now downstairs in a part of the kitchen that once housed a ‘pantry’ type store. It is just over 1m wide but has floor to ceiling access. I found a desk small enough to fit, and made some shelves to arrange the  gear on. My 2 existing PC monitors just about fit in this space, by using a supporting ‘arm’.

I have arranged my equipment so that it is easy to use and everything I need to adjust is within reach. Having an efficient layout is very important, there is nothing worse than having to stand up, stretch or reach over to adjust a control, especially when you are in the middle of a contest or chasing that elusive DXCC. My equipment is stacked vertically (as opposed to the more common side-by-side arrangements usually seen), which allows me to arrange my equipment in a very small space whilst retaining usability. The image below detail the various important components of my radio gear. The main radio is an Icom IC-756pro (the original ‘pro’ version) which covers HF and 6m. I have used Icom gear for a good many years now and rate it very highly.

I’m still tinkering with the layout to best accommodate my current operating style. It is not quite there yet, but hopefully in the New Year, I will hit on the best arrangement. Having moved downstairs, I have had to rethink my antennas. Although I have antennas in the attic, none are in use at the moment as they all require longer feeders. I have 3 outside antennas at this time: an OCFD (Off Centre Fed Dipole) that covers from 20m-6m; a Wellbrook ALA1530 active loop, with a rotator and  a Cross Country Wireless Active Loop. Images of these appear further down the page. Below is the current shack layout.

Shack 1217

Equipment list:

Receivers:

Icom IC756pro

RF Space SDR-IQ

AirSpy SDR + SpyVerter upconverter.

Funcube Dongle Pro Plus

Yupiteru MVT7100

Roberts R861/ Sangean ATS 909

Roberts R9914 / Sangean ATS 606

Degen DE1103 (non DSP version)

Various RTL R820T2 Dongles

FlightAware Prostick Dongle + ADS-B filter

Auxiliary Equipment:

MFJ 1026 Noise canceller.

MFJ 784B Audio DSP filter

Comet CAT-10 low power ATU.

Nissei RX203 HF/VHF Power/SWR meter.

Spectrum RP6S 6m Preamplifier.

DJ-Tech VTT-101 Midi controller.

Vibroplex Vibrokeyer Deluxe, Vibroplex Brass Racer and various manual Morse keys.

ANTENNAS AT G4UCJ:.

20-6m OFF CENTRE FED DIPOLE (OCFD)

I have arranged my OCFD in such a way that it does not perform as a Carolina Windom. What this means is that instead of putting a choke/line isolator on the feeder, approximately 3m from the actual feedpoint (as is usual with a Carolina Windom style antenna), I have placed the choke AT the feedpoint. This achieves is a lower noise figure as there is no part of the feeder picking up e-field radiation from nearfield electrical equipment. Although this does make the antenna markedly quieter, it does come at a cost. The cost is that my OCFD is not as good for DX as a Carolina Windom at the same height. Because I have removed the vertical section of the antenna  (the 3m section of feeder before the choke) gives the Carolina Windom a lower angle of radiation. I may experiment further, in the New Year, to see just what the difference is between the two configurations. I know from an initial test that having the choke at the feedpoint does make the antenna less prone to noise pickup (this is a pretty noisy area now). I am also considering a G7FEK style antenna which is similar in looks to an ‘inverted L’, which would move the feedpoint as far from the local houses as possible. Again, that is a project to think about for 2018.

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 14-30MHz Common Mode Feeder Choke

Below are images of the choke I use at the feed-point of the OCFD. The choke was designed by the well known RSGB columnist Ian White, GM3SEK. He has designs to cover all the bands from 160-10m. All are based on the same ferrite core -  the number and turns through them are governed by the bands of interest. It is not really possible to construct a single choke that will offer effective choking at all frequencies, but it is possible if you cascade designs that cover different frequency ranges. As my antenna only covers 20-10m, I have only used the single choke. I could increase the choking impedance by cascading a second identical choke after the first. For most purposes, the single choke should be sufficient.

When making these chokes, it is important to follow the design closely. Luckily they are simple so that is not a problem. The cost for each choke is about 6-8, depending on where you obtain the ferrite and what you have in your junk box.

Why choke the feeder? Coax fed antennas will always pick up noise on the feeder due to common mode currents flowing down the outer of the coaxial braid. This is bad news as it not only distorts the antenna radiation pattern, but it introduces unwanted noise into the receiver (and, of course, by the same token will also radiate RF from the feeder). By adding a well designed common mode choke (also called a ‘feedline isolator’), we can reduce, or eliminate these currents, thereby removing the unwanted noise before it gets to the receiver. To make an OCFD into a ‘Carolina Windom’, you move the common mode choke down the feedline so that is about 10 feet/3m below the feedpoint. It is important that the coax between the feedpoint and the choke is vertical and at 90 degrees to the radiating element. The advantage of this is that the antenna now has a much lower angle of radiation / ‘take off’, making it much better suited to DXing. The downside is the antenna will become noisier due to the vertical section picking up vertically polarised noise from the surrounding area. If you are lucky enough to have your Windom up at 15-20m or so, the noise shouldn’t be too much of a problem as you will be out of the noisy ‘nearfield’ area. For us that can only elevate to about 6m, we are stuck in the nearfield noise of everyone in the vicinity’s electronics. To further help, GM3SEK recommends using a good common mode choke on your shack mains supply and also bonding all shack equipment together so they are all at the same potential (note: this is not ‘earthing’ or ‘grounding’, which is a completely different thing and is commonly misunderstood).     

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Shown are the end supports for the OCFD. One end support is a 6m section taken from a 9m fishing pole. Using the lower 6m gives extra strength and is less ‘whippy’ in the wind. It provides some tension for the longer leg of the OCFD but still allows the wire to move in the wind. The other end support for the OCFD makes use of a redundant TV antenna. The top of the TV antenna must be a good 9-10m above ground, and I have hooked the supporting cord for the OCFD over it and that is tied off at the fence. The feedpoint of the OCFD is supported by a 10m aluminium telescopic mast. I have never had it higher than about 7m, which helps to keep the peace with the neighbours, also it means that the mast is strong enough to hold the OCFD and other smaller antennas.

WELLBROOK ALA1530 ACTIVE LOOP

My Wellbrook ALA1530 active loop antenna (ALA1530) has, at long last, being used to its full potential.  I have tried it in a number of positions, the latest one being on the side fence near to the bottom of the back garden. This is about 10m away from the nearest house and is, for the first time, mounted on a rotator. The base of the loop is about 4m (13 feet) up and attached to the fence with a wall bracket. I have fitted a bamboo cross brace for some extra protection against the high winds we sometimes get as the location is quite exposed to the West and South. 

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CROSS COUNTRY WIRELESS (CCW) ACTIVE LOOP

A new addition to my antenna arsenal is a Cross Country Wireless (CCW) Active Loop. This is a great antenna, it has a small footprint and is easily portable. I have used this antenna on a mini DX-pedition to Suffolk, and it worked very well. The loop covers from 150kHz right up to 70MHz (in fact it covers 2m and beyond - I have received good signals from some distant DAB multiplexes up in the 180-230MHz range). This antenna will cover most things you want to listen to, and is fed not by the usual coax cable, but instead by CAT5 ethernet cable! This means there are fewer losses and common mode noise can be all but cancelled out. The (CCW) Active Loop is a triangular loop approximately 1.5m across. Ideally the loop needs to be as high and as in the clear as possible. This not only gets it out of the near field noise area of your house, but will also help signal pick up of VHF ground wave. I have used this antenna mounted at about 7m up on top of my mast and it performed very well. I hope to get it back on there at some point. Like the Wellbrook loop, the CCW antenna is directional. They both have sharp nulls, which can be a real asset when trying to reduce local noise pick up. In actual fact, the nulls on the CCW are sharper than those of the Wellbrook. At VHF, turning the antenna reveals signals that were otherwise hidden. Also, the radiation pattern is complex and appears to pick up both horizontal and vertical signals equally well. Most useful for VHF Band 2 DXing as I can hear coastal France pretty much all the time (usually horizontally polarised), but at the same time I can hear distant vertically polarised signals from the UK. All in all, it is a great antenna. CCW do a couple of other active antennas, you just need to choose the one that fits your criteria the best. You will also find useful accessories such as zero loss antenna splitters, HF preselectors and their own design SDR receivers. Worth checking out their website.

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Alternative Antennas (not currently used, but available when required)

I have a collection of various antennas that I have built up over the past few years and use them according to my current area of interest. In an ideal world I would have all operational and mounted outside at a respectable height. However, this is real life and it is not possible to have more than I already have up at any one time (unless I can find a way to mount another one without it being obvious).

So what antennas do I have in my collection?

Discone: covers from 25-1300MHz (the bottom end is not very good, but from 70MHz up it is not bad at all).

6/2/70 White stick vertical: Useful for 2m and 70cms. Also have a 20/70cms vertical, similar to other one but lacking 6m.

137MHz Turnstile: Great for receiving NOAA weather satellites as it is circular polarised. Also works reasonably well on 2m and VHF broadcasts as it is only 6dB down on both horizontal and vertical so receives both polarisations quite well. Also has some gain over a dipole as it is 2 pairs of crossed dipoles.

5 element Band 2 yagi: Great antenna for the VHF FM broadcast band. Will be put to use again soon, in the attic facing South East, ready for Sporadic E openings in the spring.

HF dipoles: wire dipoles covering roughly 17m, 15m and 12m, currently in attic and facing E/W.

2ele vertical colinear for 1090MHz (1.09GHz, ADSB): Excellent antenna for hearing aircraft ADS-B beacons, when used with FlightAware Prostick Dongle and ADS-B bandpass filter.

 I would like to add a 4 element 2m LFA Quad to the collection at some point in the future.

Disclaimer:

I do not have any affiliation etc, to any of the manufacturers mentioned, I’m just a happy user of their gear and feel it my duty to pass on my findings so that it may help others who are looking to change their equipment.

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