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After enjoying a number of VHF UHF / Microwave field days in recent months, I decided it was about time I wrote a few words about the experience in the off chance that it may act as a catalyst for one or two of you to “give field days a go”!
This article is not intended to give a definitive solution to the topic of field days but rather to provide an exposé’ on how I went about assembling a field day station that has given me many hours of enjoyment.
Much of the detail relating to specific pieces of equipment that I have used in the field day station can be found elsewhere on this Blog!
To begin this exposé’ I think it is important to identify what was and has been the motivating force that has driven me to build my field day station. Put simply, I wanted a station that:
(a) covered a variety of bands within the class of field day eg.,(VHF UHF / Microwave),
(b) had antennae that provided adequate gain without being critical to point,
(c) was simple to transport,
(d) assembled easily (one man),
(e) was reliable and had dedicated equipment,
(f) provided a self contained power system (batteries, solar panels and generator)
(g) had an operating position that protected the operator from the elements,
(h) was a pleasure to operate in a variety of locations.
With these factors guiding my every step, I began what has been quite a challenging project!
The first step was to decide what range of frequencies I was going to provide for my portable field day station. From my observations of over fifty years of amateur radio, the field day activity in Australia is clustered into two areas of the spectrum – above and below 50 MHz. This article will only focus on 50 MHz and above with the highest frequency being 10 GHz.
The next step was to consider what type of antennae would be practical for each of the bands and making sure that the correct polarisation was available for the respective modes to be used throughout the chosen spectrum.
In Australia most of the SSB contacts on the various bands 50 MHz and above, use horizontal polarisation while FM contacts use vertical polarisation, so it was very important that if maximum contacts were to be enjoyed, attention to the polarisation issue was important.
Mounting the 6 m Halo.
The antennae that I chose provide maximum flexibility without requiring me to be constantly adjusting the azimuth just to make contact. I also chose to use a YAESU variable speed, computer controlled rotator, that provides (all weather) azimuth adjustment from the operating position.
The antennae that I have used are;
(a) 6 m Halo or 3 ele Yagi (horizontally polarized)
(b) 2 m Halo or 8 ele Yagi (horizontally polarized)
(c) 70 cm 13 ele Yagi (horizontally polarized)
(d) 23 cm 19 ele Yagi (horizontally polarized)
(e) 13 cm 600 x 400 mm Grid Pack ( horizontally polarized)
(f) 9 cm 900 mm off-set Dish (horizontally polarized)
(g) 6 cm 600 mm off-set Dish (horizontally polarized)
(h) 3 cm 300 mm prime-focus Dish (horizontally polarized)
(i) 2 m, 70 cm, 23 cm Tri-band Vertical (Diamond X-5000N)
(j). Active GPSDO Antenna (powered via coax feed)
Having operated in field days for more years than I wish to remember, the most critical part of the station has always been the mast which was and has been either too heavy for one man to erect or too light which invariably bent in the middle when attempting to raise it into position! With this in mind, I was determined to find a better way.
After considerable thought and research I was sure what I did not want. I didn’t want a mast that;
(a) attached to my car in any way,
(b) required pegs driven into the ground or what ever surface I happened to be parked on,
(c) needed more than one person to erect,
(d) relied on the “armstrong” method of antenna rotation,
(e) used my car to transport a variety of lengths of pipe and antennae,
(f) didn’t allow all of the antennae outlined above to be mounted on the same mast.
With all these thoughts and criteria buzzing around in my head, the gem of an idea began to develop! It soon became obvious – the best solution for my needs would be a “box-trailer” mounted system.
With the decision made, the system began with a 50mm steel angle-iron frame that could be slipped into the base of a 1800×1200 box-trailer and bolted to the base (this meant that it could be removed when not required for field days). Cross braces were then added to the base frame to allow a central ” gin-pole” to be positioned which had an internal pulley added to the top and tripod support braces to ensure stability. A winch was added to facilitate the raising of the mast using the gin-pole. The mounting for the mast rotator was accomplished by attaching a hinged mast stub at the base of the gin-pole. A piece of 50 mm angle was bolted to the gin-pole near the top which would assist with anchoring the mast bearing when the mast was in a vertical position.
The last requirement was the mast itself. It needed strength, but could not be too heavy; it must be capable of collapsing to form manageable “one man” lengths and be at least six meters in length when assembled. The final solution was a 50 mm scaffolding tube that was cut in half and sleeved. The sections were pushed together and bolted when assembled. Cross arms were added to the bottom section for mounting the Microwave Antennae and Transverters. A small offset sub-mast was added to the top section to mount the GPSDO antenna.
After manufacturing all of the components and assembling the system, one final problem presented itself. How was I going to carry all of the antennae and mast sections safely?
The accompany photographs show how a series of mounting brackets have been added to the assembly to facilitate the transporting of all of the antennae. Labels have been added to ensure that all of the components are returned to their respective locations. Yes I could have just bundled all of the antennae and lay them in the trailer but by having a specific location for each component, nothing is forgotten and most importantly, nothing gets damaged!
The operating position in a field day station has always been an issue for me as it seems to be the forgotten ingredient in what can be a well planed expedition into the field. I know I have been guilty of thinking I will just take a small table and that is all I will need. While I have managed to do this on a number of occasions, I have had some monumental failures with tables collapsing resulting in damaged equipment etc. Having gone to the trouble of working out a suitable antennae system, I decided it was time to have an operating position that was easy to setup, functional and sturdy.
During my frequent visits to the hardware store, while constructing the antenna system, I became aware that the “Stanley Tool Company” was selling a “Fat Max” toolbox with wheels, that has three major storage areas that could adequately store all the cables and minor components for the portable operation and also act as a console for mounting the transceivers. In addition, the lid of the toolbox could be used as a operating desk with the addition of a three-ply insert and a support strut. The accompanying photographs show the toolbox in operation.
With the system components completed, the next area to be addressed was the power system. When operating portable, I usually rely heavily on battery power that is separate from the vehicle battery. In the past I have tried to use the vehicle battery as part of the power source with disastrous results ( modern vehicles and flat batteries don’t mix)!
I therefore decided to use 2 x 150 ah AGM batteries supported by 160 watt Solar Panels for daytime operation. This decision has proven to be most satisfactory with an average of 12 amps per hour being fed back to the batteries under good sunlight conditions. During the evening however, battery charging is achieved by using a Honda EU20i, 2 Kva generator that feeds a CTEK 25000 series Smart Charger that is very effective at keeping the batteries fully charged. The Honda Generator is extremely quiet acoustically and electrically. These factors, coupled with good fuel efficiency, have proven to be an excellent addition to the Field Day Station.
Weather conditions are a critical factor in the field especially when considering operator comfort and over the years I have tried a variety of shelters / tents etc., however I have never been totally happy with the amount of equipment / effort that was required to setup a suitable shelter. What I really required was a shelter that was attached to my vehicle, that I could assemble by myself and provided all weather protection. The Supa-Peg RV Awning that is manufactured in South East Queensland, matched all of my requirements and has proved to be an excellent all weather shelter that can be setup in a matter of minutes.
No field day operation would be complete without some method of storing a cold drink, milk and food. This has been achieved by using a WAECO 35 L – 12 volt fridge/freezer that has done the job very well indeed.
Well I hope this article may have provided some ideas for one or two of you who are thinking of going into the field. This project has certainly made “Field Days” fun for me.
The Brisbane VHF Group organized a very successful Microwave Activity Day on the 28 October 2012.
Prior to the day numerous stations had indicated that they would be in the field and operating on a number of the Amateur Radio Microwave Bands. The locations for these stations centered on South East Queensland and into northern New South Wales. It was also identified that the activity would begin at 0900hrs local and continue until mid afternoon. It had also been established that the first hour would be dedicated to 23cm and 13 cm. After 1000hrs all Bands would be used. The Brisbane 2 meter Repeater was to be used for liaison after 1000hrs with 146.550Mhz simplex being used as a backup. It was also suggested that checking the VK Logger to ascertain the locations of the various stations and the actual contacts being made would be an advantage.
With all these factors in mind it became obvious that to participate successfully in the day I needed to setup my full VHF, UHF & Microwave field day station.
The Microwave Bands to be covered were 23 cm, 13 cm, 9 cm, 6 cm and 3 cm using individual Transverters and Antennae.
The IF Transceiver for all the Transverters is a Yaesu FT817 ND that is mounted in the central console. Switching to the required Transverter is accomplished by rotating the silver knob in the centre of the console. A detailed explanation of this system is given elsewhere on my Blog.
Liaison was accomplished using the ICOM IC7000 Transceiver with a Tri-band vertical antenna (2m, 70cm & 23cm) located at the top of the mast.
I used an Apple MacBook Air laptop computer to interface with my Thunderbolt GPSDO to ensure frequency accuracy of all the Transverters and the laptop also allowed Internet connection via a Telstra 3G WIFI Hotspot Modem to access the VK Logger.
The DC Power for the entire operation was supplied by a 12 volt 150 Ah AGM Battery. The power cables all use Anderson 50A polarized plugs to feed the equipment.
GPSDO and power distribution.
As with any portable location a covered operating position was required and this was provided by a rollout awning from the vehicle.
The awning made operating very comfortable.
The day started under overcast skies but it soon became apparent that it was going to be a fun day and the effort involved in setting up the station was worth the time involved.
About to setup at the Mt Gravatt site.
Assembling the mast.
Running the cable looms.
About to raise the Mast.
Mast raised and locked. The antennae shown from the top of the mast are the Tri-Band Vertival, the GPSDO, 6m Halo, 70cm Yagi, 2m Halo, 2.4Ghz Grid-Pack, 23cm Yagi, 3cm 30cm Dish, 5.7Ghz 600mm Dish and 3.4Ghz 900mm Dish.
In contact on 3.4Ghz.
All working and performing well.
In QSO while monitoring the VK Logger.
It’s 1500hrs and time to pack up and head for home – a great day!
The day was very successful and a most enjoyable time was had by all. I was fortunate to have all the equipment perform as expected and I made multiple contacts on all bands.
Thank you to all of you who have asked questions about my Portable Microwave Station. I hope the emails I have sent have gone some way to answering the many and varied questions raised. There has however been quite a number of questions asked that have centred on the main operating position and specifically how the Microwave Transverters are controlled from the operating position. This post will attempt to describe how I went about solving this issue and how I have assembled the HF, VHF and UHF transceivers that I use to ensure maximum operating efficiency while providing maximum protection for the equipment.
The centre console is built into a “roady” 19″ rack case that has been divided into two sections using a central divider on to which has been mounted a series of supports that hold the Transceivers.
Beginning at the top left is a YAESU FT8800R Dual Band (2m / 70cm) FM Transceiver. Under this Transceiver is a YAESU FT817ND (HF, VHF, UHF) Multi-Mode Transceiver that provides the RF drive and IF/PTT for the Microwave Transverters. The selection of which transverter is to be active is controlled by the control knob at the top centre.
Below this transceiver, still on the left hand side of the case, is an ICOM IC1200 (23cm) FM Transceiver. This transceiver and the FT8800R are connected to a Triplexer system that feed a Diamond Vertical that is located at the top of my portable mast. Primarily these two transceivers are used for liaison when operating portable. The YAESU FT8800R has the additional feature that permits it to operate as an FM repeater if required.
On the right hand side of the case is mounted an ICOM IC7000 (HF, VHF, UHF) multimode Transceiver that delivers SSB on all the band up to and including 70cm. This transceiver produces 100 watts PEP on all bands up to and including 2m and 75 watts PEP on 70cm.
Below this transceiver is an ICOM AT180 Automatic Antenna Tuner that operates up to and including 50 Mhz. This unit allows for tuning out a small mismatch when transmitting across the various bands.
The console has front and back covers that totally enclose the equipment when not in use. The case is made from very robust material and therefore has the potential to standup to the rigors of portable operation.
In addition access is also gained to the remote transverter connections that are positioned in the centre rear. This switching system is connected to the front selector switch using an extension shaft.
There are two connections on the to the remote switch, the one on the left provides 12volts DC to control the “Relay Switching Tree” and the second at the base is a 7 core cable connection that provides relay control of the relay tree.
On the lower lip of the case there are two pop-rivetts that support a small aluminium bracket that is used to anchor all the external cables using “velcro ties” thus removing strain on all of the connections.
The central bar that can be seen running across the rear of the box is an earthing bar to which all of the Transceivers are connected.
The seven core cable that is connected to the rear of the console is 10 metres long allowing the centre console to be placed in a convenient location well clear of the portable antenna system.
As shown in the photograph, the relay tree provides six (6) outputs for connecting to the Transverters. When active, a green LED is lit signifying the active output connection. Each connection provides an IF connection back to the YAESU FT817ND when receiving. In the transmit mode RF is sent to the selected Transverter with the PTT voltage sent to the Transverter via the centre conductor of the coax.
The following image shows the interior of the relay unit.
This view shows the six (6) relays and associated interconnections. The relays are labeled to assist in identifying what their role is in the overall operation.
The connector on the left hand side of the box accepts the RF, PTT and IF connection from the Transceiver.
The connector on the right hand side allows the seven core cable to connect to the relays.
The following images show the various components of the relay system.
The relays were positioned into cutouts in the double sided PC board to allow ease of assembly and to provide a ground plane that provides a low impedance grounding system for all of the components.
The enclosures used for the relay system are die-cast boxes that provide easy assembly and good protection for the components.
The system works well and makes the process of switching from microwave band to microwave band a very simple process. The LED’s positioned at the centre console and at the remote relay tree, make it a simple process to keep track of which transverter is active.
From an operational point of view, the system is very convenient and simple to use and makes the action of switching from band to band a very simple process!
I hope these few words and the accompanying images provide an insight into the way a central console and remote switched transverters can make portable operation more enjoyable!
A number of questions that I have received have prompted me to publish the following images that show a close up of the Tri-pod Dish mounts that I used on 3.4 and 5.7Ghz.
The assembles were constructed using galvanised post stirrups that are available at a number of hardware stores.
The stirrups were bent to produce an angle of 68degrees from the horizontal or if you prefer the reciprocal 22degrees from the vertical. This angle was then reinforced by inserting a gusset into the open end. I could have weldered the gusset but decided that the bolted gusset gave me a little more flexibility as some dishes require a 65 degree angle.
These angles ensure that the focal point of the dish points to the horizon.
There a number of anticles on the internet that discuss how to calculate the angle that is required for specific types of dishes.
I am sure the creative among you have other ways to solve this problem but this method worked for me.
The whole assembly is bolted to the try-pod using a 5/8 whitworth galvanised bolt that is usually supplied with this type of tri-pod.
In using this method the Dish mounting the mounting pipe for the dish is set at the correct angle to mount the off-set dish.
I hope those who are attempting to use this type of tri-pod are able to gain some ideas from these images of the solution I used to good effect.
How often have you gone for a drive in the country with the family on the weekend only to find yourself parked at a scenic location with sweeping views of the surrounding countryside and thought – “wow what a great location to try for a Microwave Contact”!
Sadly, this I suggest happens all too frequently and an opportunity goes begging because your microwave station is “hardly portable” and the family would certainly object to having the car loaded with that “radio junk”!
I think I may have an answer to this age old dilemma but before I go any further I must ask the obvious question and if the answer is “YES” then you may be having that Portable Microwave contact sooner than you think!
The obvious quest is; would these five items fit in the boot of the car?
If the answer is YES then I am sure the family would have little complaint and yes you guessed it you too could be operating portable on one of the Microwave bands from that idilic location.
Many questions have been asked of me as a result of this microwave series of posts on my blog but none more often than “How do you put a portable microwave station together easily, quickly and with repeatable performance”.
This post focuses on putting all of the components of a portable microwave station together simply.
I know there are many articles on the internet that have shown portable microwave stations but I found they didn’t seem to provide a solution for me.
The following outlines the way I went about assembling a portable microwave station that is easily transported and simple to assemble and operate. In addition the assembly provides a place for everything and every thing in its place.
I am sure the creative among you will no doubt have alternative methods to solve this problem but to coin a phrase “I have done it my way”!
In developing this project I was determined to work with a minimum number of components that were simple to assemble and transport. I also wanted to ensure that all the pieces fitted together so that when operating the Portable Microwave station the operator didn’t need to be an octopus! Further when assembling the station there was no need to have equipment perched precariously while trying to establish a contact. I was also determined that the portable microwave station would be free standing with no dependance on vehicles or surrounding objects.
The initial five pieces shown above have been selected to meet all of these goals.
To begin with, I decided to select a photographic tri-pod to support the entire station. The tri-pod that I chose has a “quick release” section for mounting a camera that clips into the top. I removed the wing nut assembly from the centre of this unit and replaced it with a 1/4″ galvanised bolt that attaches to the angle bracket at the base of the transverter.
The next component to be selected for my Portable Microwave Station was a 12 volt 40Ah sealed battery to which I fitted a polarity sensitive, o/l protected distribution housed in a PVC Box that provided a number of 2 pin screw connectors, four sets of Red and Black Terminals in case I needed 12 volts and a cigarette lighter socket, in case I need to charge my Cell phone while operating portable.
My next thought was focused on how was I going to mount my YAESU FT817ND so as not to have it balancing precariously making operating difficult.
For those of you that have one of these transceivers you will be aware that they don’t have a cradle and therefore mounting is difficult. My solution was to make an aluminium cradle system that utilised the two carry strap bracket mounting screws at either side of the transceiver at the front and anchor the rear of the cradle using the earthing screw at the back of the radio. However if this was to be successful then I would need to provide a cut-out in the cradle to ensure that the sound from the FT817ND speaker was not baffled. Once I had the cradle, I then needed to work out how to mount the Transceiver onto the tripod in such a way as to provide easy access to the controls and a clear view of the dial. An additional requirement was to provide a mount for the microphone because as all of you who have operated portable will know, the microphone is always seems to be in the wrong place at the wrong time or just simply dangling from the transceiver.
When operating Microwave Portable there is one other piece of equipment that is indispensable; a Handheld Transceiver for liaison!.
In reality the solution to the problems outlined turned out to be quite simple.
I manufactured a bracket from aluminium that solved all of the issues! A place for the Transceiver, a means of locating the Handheld Transceiver right at the operating position and a microphone clip that was easy to use.
The final assembly relies on the fact that the tri-pod I selected has ferrules, that control the extension of the tri-pod legs at a suitable hight for mounting the Transceiver. By forming the bracket with a “fork” at one end that is covered with heat shrink tubing for protecting the paint work on the tripod. On the opposite end of the bracket it has just one leg of a fork with the second leg formed by a slide that locks the whole assembly together.
The Transceiver bracket is set at an angle that allows the cradle to slide onto a tongue that gives a perfect viewing angle for the Transceiver screen.
The last task was to make provision for charging the Handheld, the FT817ND and powering the microwave transverter. This entailed assembling a distribution system that provided correct polarity for the equipment and overload protection for the battery. It is controlled by a single switch which will only turn of the supply to the equipment if the polarity is correct. The connectors are all polarity keyed and provide a screwed connection.
To this was added a series of cables that were labelled to indicate their purpose and to provide speed in assembly of the station. (Power for the Transverter, RF / PTT from the Transceiver to the Transverter, Charging for the Handheld and charging for the FT817ND)
To ensure that nothing is left behind all of the cabling, the Yaesu FT817ND, the distribution System and the Handheld transceiver all fit nicely into an aluminium case for ease of transport.
The system works flawlessly with a set up time of about 10 minutes.
The capacity of the battery ensures many hours of trouble free operation.
This Microwave station has been a lot of fun to develop and even more pleasing to operate. I have further developed the idea to cover a number of the Microwave Bands all with equal success.
I hope this post will give someone the incentive to have a go at operating portable on one or more of the Microwave bands from one of those fantastic locations that often get visited when taking that leisurely drive in the country.