The Centre Console for a Microwave Portable Station

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.

This is a view of the Centre Console and Microwave Transverter Selection Control

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.

This is the back panel that has to catches that lock it in place.

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.

This is the Front Cover which has clips on each side that holds the cover to the main case.

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.

The rear of the console with the remote transverter switching system in the centre.

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 completed Relay Switching System.

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.

The interior of the relay switching system.

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.

Relay Assembly prior to wiring!connector on the right terminates the seven (7) core cable from the central control switch on the main console. In reality I use 8metres of cable in my portable installation.

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.

All the components for the remote switching system.

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!

Mounts for Off-set Dishes

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.

Another View of the Off-set Dish Mount

The assembles were constructed using galvanised post stirrups that are available at a number of hardware stores.

Dish Mount for 9cm Off-set Dish

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.

3.4Ghz Dish Mount

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.

A Simple Portable Microwave Station

An Ideal Portable Microwave Location

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”!

Assembled and Ready to Call CQ on 10Ghz

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.

A Microwave Station Packed and Ready to Go!

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”.

All of the Components of the Portable Microwave Station

This post focuses on putting all of the components of a portable microwave station together simply.

Powering the Station

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.

QRV on 10Ghz

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 Power Source and Distribution System

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.

The Main Items that make the System Foolproof

When operating Microwave Portable there is one other piece of equipment that is indispensable; a Handheld Transceiver for liaison!.

A Place for Everything and Everything in Its Place

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.

Transceiver Cradle and the Rear of the Mount

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)

Keeping it all in one place.

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.

Picture Gallery – A Simple Portable Microwave Station

Basic Solution for Becoming QRV on 10 Ghz

Judging by the number of emails I have received over the last two months since I began publishing details of my construction activities in the Microwave Bands, there are a great number of Amateur Radio operators who would like to participate in the challenge of the Microwave Bands but are unsure as to how to start.

Assembled and QRV on 10Ghz

I have written this article to show how I went about starting!
However while it is clear from surfing the Internet, that there are many ways to get started  in the world of microwaves,  I decided to “bite the bullet so to speak” and have a go at doing it my way!

To begin with, I decided that I was happy to build the entire project which inevitably involved working with “surface mount” components and while I appreciate not everyone has had experience in this area of construction, it is undoubtedly the way of the future for most electronic solutions.

In deciding to take the route of using surface mounted components, the age old problem of component lead lengths in the Microwave spectrum becomes one less problem to deal with!

All Ready To Assemble

The next question that presented itself was; do I really want to start from scratch or would it be more logical to start with  a ” kit of parts”.

To cut a long story short, I decided to embark on the journey by using a kit. This decision overcame a number of issues; the development of a printed circuit board, the sourcing of all the components and by taking this route a tried and tested solution presented itself. These factors coupled with the desire to use minimal test equipment to achieve a positive result was the final consideration that brought this project sharply into focus.

This last issue is not really a problem for me as I have, at my disposal, the resources of a fully operational development/prototyping laboratory but I wanted to produce a project that did not rely on any of these resources and I guess that deep down I just wanted to see how hard it would be to become QRV on the Microwave Bands using simple everyday tools.

The Basic Building Blocks

As mentioned previously, I have spent considerable time on the Internet looking at how other people became QRV on the Microwave Bands and I soon concluded that DB6NT’s experience and reputation for quality, simplicity and value for money was hard to beat. Further his designs and ultimate tune up procedures made it impossible to dismiss.

In addition to the above, the solutions offered by DB6NT came in a kit form with every component supplied and at an overall cost that was better than any other solution I could find!

In deciding on this course of action, it is not my intension to indicate that there are no other solutions available; there are, but they just didn’t work for me!

Over the last two years I have built a number of these kits for a variety of Microwave band and reconditioned quite a few of the assembled kits that came from a number of sources, that for a variety of reasons, never really became operational on the air due to inbuilt faults or incorrectly placed components. In ALL of the cases the kits once correctly assembled worked well and were easy to tune. With respect to two of these kits that I re-furbished, I stripped the boards and started again.  During this refurbishment process I only needed to replace the odd device or component that had been damaged by heat. The printed circuit board in both instances survived, a testomney to the quality of the printed circuit boards supplied with the DB6NT kits.

Complete and Ready for the Top Cover

It is not my intension to go through the component assembly of the DB6NT Kits as there are many examples available on the Internet outlining the precautions and procedures to be used when working with these products. In addition there is the potential to download assembly instruction for all of the DB6NT products.

The tune up process is very simple indeed and can be accomplished by using a standard “multimeter”. I believe one of the reasons that this process is so simple relates to the basic design. Once the tune-up stage is started it soon becomes obvious that when tuning the individual tuned circuits, there is only one resonant point in the tuning range! This fact alone makes the entire tune-up process quite straight forward and easy to complete.

Upon completion of each microwave system that I have built, I  used the range of test equipment at my disposal, to check the results obtained using the simplified tune up process and in each case I was unable to better the tuning. In the case of the transmitter, the output power produced was clean with an output equal to or slightly greater than the published specifications.

The Meter Scale

The accompanying images show the Basic 10 Ghz transverter assembly and the associated hardware used. This unit produces a clean 250mw output at 10Ghz from a 144Mhz - YAESU FT 817ND Transceiver driving with a 1W output.

The project was assembled into a “die-cast” box that I pre-drilled  as shown. The small brackets were made from aluminum scrap, again pre-drilled as required. All of the basic components (switches, connectors, etc) are readily available from a number of component suppliers. Yes I do have a junk box with all manner of components that I could have used however because I wanted to replicate the design for most of the Microwave Bands and I wanted to standardise on all of the components where possible.

The meter scale was developed in Photoshop and then printed onto “matt” photographic paper using a colour laser printer. The original meter scale was removed an used as a template. The meter has a 50uA movement.

The RF interconnections are based on UT141 hardline and associated SMA connectors. This coax is simple to use with acceptable performance to 10Ghz but this can be stretched to 20Ghz in short runs. The coax to waveguide right angle converter that I have used to feed the “prime focus” dish is an “N type” made by HP however there are many brands that are readily available on eBay.

The SMA antenna change over relay is made by “Teledyne” that has a 28 volt coil and has a maxium usuable frequency of 18Ghz. These are also available on eBay.

This relay is driven by a simple power supply based on a NE555 timer. I don’t know the designer of the circuit, but I have used this standard circuit for a number of years in a variety of projects with great success. The ciruit was published in the earley 1990′s in a NE555 time application note. There are many similar power supplies that can be used, all of which are capable of driving the relay successfully.

In assembling this microwave project I have routed the control circuit wiring through aluminium tubing. This is a technique that was pioneered by NEC  in their microwave link equipment in the 1980′s. It provides good RF bypassing / shielding and because most of the impedances encounted in this project are low, there is little chance of RF feedback being an issue, however when this technique is used, this issue is eliminated. (To prove a point I ran an RF sniffer around the system while transmitting and could not detect the presence of any unwanted / stray RF). It also provides an ideal solution for maintaining stability of all control circuits especially when the equipment is moved from location to location for portable operation.

The angle bracket at the base of the assembly allows the unit to be mounted on a photographic tripod.

The Mounting bracket and Quick Release Tripod Mount

The Prime Focus Dish used in this solution is 300mm in diameter and was originally used for aircraft weather radar with a gain of 21dbi.

QRV on 10Ghz

The unit has been a lot of fun to construct and put into operation. Just as an aside the kit used in this project was purchased off the internet in a rather dilapidated state requiring a complete rebuild. (All the components were stripped off the printed circuit board and I started again). What did it cost  on eBay – A$80 a bargain and without a doubt well worth the restoration effort!

The observant among you will have noticed in the initial assembly of the project components the “antenna change over relay” had its terminals on the top of the relay, however the images of the finished unit has the connections on the bottom. The reason for this change resulted from a faulty / intermittent relay that had to be replaced. This by the way, was the only failure that happened in the assembly of this project.

I hope I have answered some of the questions that your emails raised and has given someone the incentive to “give it a go” and become QRV on the Microwave Bands.

Protecting the DC Power Source While in the Field

The need to know the condition of the power source for any field day / portable station is a major priority. The requirement to know exactly how much current is being drawn by all of the equipment at any given moment during the stations operation is also paramount.

When operating portable, sometimes in the remotest of location, to suddenly loose power due to a battery failure, when that illusive Grid Square is on offer, is nothing short of a disaster.

Coupled with the above, is the disaster of all disasters, a short circuit in the equipment or its cabling that puts a “dead short” across the power source! That pungent smell of melting plastic is not something I wish to experience when operating in a field day / portable location.

Lastly that impossible scenario, when arriving at the appointed location with minimal time to setup and then applying reverse polarity to the equipment, was not something that I ever wanted to happen!

Yes I have been guilty of experiencing all of the above over my 50 plus years of amateur radio operation, but it is something that I was determined not to have happen with my field day / portable operation this time around.

The following examines the Power Distribution System that I have used for my Microwave Project to ensure, as far as practicable, the mistakes of the past will never happen again!

DC Power Distribution

To begin with, I was determined that all cables feeding every piece of equipment would have an in-line fuse in the DC line. Further, every cable would be terminated with a connector. In the case of all the microwave transverters, every power connector would have the same type of connector that is keyed to prevent reverse polarity.

Every Transceiver DC Power feed, while having an in-line fuse, has a different style of connector fitted to ensure that the correct fuses are used for each transceiver: (eg the current drawn by an ICOM IC7000 is greater than that drawn by a YAESU FT 817ND)

Transceiver DC Cable Harness

Lastly, the power distribution system must accommodate meters for Voltage and Current, an Overload Circuit Breaker, Input polarity sensing and be sufficiently robust in construction, to allow the unit to be placed in any convenient location.

The  images show the final DC Power Supply distribution system. The handles on the front of the system are important and are not there for cosmetic effect. They were actually placed to protect the meter faces from accidental damage!

Portable 12 Volt DC Distribution

The internal workings of the power distribution system are the essence of simplicity. A number of basic designs were considered and then rejected. In the end, the system has met following design criteria:

Inside the DC Distribution System

A single switch isolates DC Supply from all devices.

Voltage drop between the input and the output is essentially zero (the purists will know that is not true, as if metering is introduced into the line, there will be some voltage drop but in this case it is insignificant).

All connections to the distribution system are via plugs and sockets that are rated at the maximum current that could flow under peak load conditions from the connection.

Interconnection cables are rated at the peak load that could be required by the respective connections

Under “overload conditions” the circuit breaker included will not reset instantly, but will reset after a short period of time, thus preventing the dreaded “on/off/on” condition.

Polarity reversal  results in non operation, rather than the destruction of a fusible link or the tripping of a circuit breaker.

Metering is achieved using separate meters for Voltage and Current rather than a ‘multi-meter” style of operation.

Meter Scales are easy to read and not confusing to check the status of the DC Supply System quickly.

Footnote:

A safety warning when using portable generators in the field

As mentioned in another article I use a Portable HONDA 2 KVA generator to charge the batteries via a multi-stage charger when operating for extended periods in the field. I am never ceased to be amazed at the number of amateur radio operators who use a similar system but fail to protect themselves and there second operators from electric shock.

I use a residual-current device (RCD) positioned at the generator just in case. As an Electrician and an Electrical Engineer I have seen, at first hand, what can happen when someone, in most cases through no fault of their own, become connected to 240 volt AC. It is not a funny experience and depending on the situation it can be lethal. These devices can be purchased for a very small cost and add a level of electrical safety that all should heed!

For those who are interested, a residual-current device (RCD) is an electrical wiring device that disconnects a circuit whenever it detects that the current is not balanced between the energized conductor and the return neutral conductor. Such an imbalance is sometimes caused by current leakage through the body of a person who is grounded and accidentally touching the energized part of the circuit. A lethal shock can result from these conditions. RCDs are designed to disconnect quickly enough to prevent injury caused by such shocks.

Assembling a Portable / Field Day Station

Assembling a Portable Station

Over last few days I have received numerous questions relating to how the equipment, shown in my Winter Field Day Project, is connected to make a functional portable station.

The following “Block Diagram” shows how all the components are connected and how they interact. While this may appear slightly daunting at first sight, in reality, it can be divided into five (5) sections:

1. Power Sources
2. RF Generation
3. Signal Routing
4. Antenna Options
5. Computer Control

These sections are all inter-dependant and crucial to successfully assembling a functioning portable station. Section one (1) is however the critical area with the capacity to make or break the operational efficiency of the portable station if it is not well developed.

The “Block Diagram” is not a wiring diagram; but instead, it is intended to show the relationship of all of the portable station components required to establish a successful station in the field. In a practical sense each or the interconnection in the system are labelled and rely heavily on the fact that different plug and socket combinations are used to simplify the whole process of inter-connect, thereby overcoming delays in assembling the station quickly.

The entire Portable Station revolves around the Radio Console that houses the RF generation of the portable station. However, as outlined above, without the power system / sources, this portable station would not function.

It is therefore prudent to begin the explanation of the “Block Diagram” starting with the power system which has as its centre piece two (2) 150ah AGM Batteries.

The AGM Batteries were selected for two reasons:

The robust construction and lack of soluble acids in the manufacture of AGM batteries.

The “charge – discharge” cycle of AGM batteries is preferable to many of the “deep cycle” batteries used in many portable situations today.

While these statements tend to prompt debate in some circles, from my experience working in engineering projects, with both types of batteries in a variety of situation in this country and else where, has shown that the AGM batteries are the clear winners for portable operation.

While it is important to select the correct battery for the task, it is equally important to set up a system of charging that will provide many years of good service from the batteries being used. It has been my experience that without appropriate care and attention (this also entails the charging process), even the best battery will fail. Charging a battery involves more than just placing any old charger across its terminals and hoping for the best! Charging of today’s modern batteries is about obeying the rules of the battery manufacturer and this extends to the use of a multi-stage charger. These chargers ensure maximum charge is applied to the battery in a form and time frame to produce long and efficient service. To achieve this I have included the CTEK 25000 charger in my portable configuration. The advantages of this type of charger have been well document in Trade Magazines, Caravan and Motor Home Magazines and on the internet by a variety of sources and therefore the need for further discussion in this forum is unnecessary.

During daylight hours I use 160watts of solar panel to trickle charge the batteries thereby prolonging the time between charges. In the evening I use a 240 volt AC 2kVA Honda Sine Wave Alternator as the charging source.

The “Block Diagram” also shows that, when running the Honda Alternator, two additional power supplies are used, one to supply the ICOM IC7000 Transceiver and the other to charge the Laptop internalBattery. The Laptop Computer usually has an operational time from its internal battery of approximately 7 hours. While this is a relatively lengthy time for a laptop battery to last, it hardly sufficient for long duration Field Days. To assist in this regard a portable power supply was selected that provided dual input that allows the  laptop to be charged from the Honda alternator 240 AC output as well from the 12 DC battery supply.

For a portable power supply system to be successful there is a need to consider how and where the supply is routed and how the power source is protected. This system is no different; with all cables being terminated in a common plugging system that checks the polarity of the source and also provides overload protection. To this is added a metering system that displays the DC supply Voltage and Current drawn by the total system.

It should be noted that in this system there are no unterminated cables in the DC line, so the potential for reverse polarity or short circuits have virtually been eliminated.

RF Generation is the next area of focus in the “Block Diagram”. The system uses five (5) transceivers to ensure total flexibility of the portable station. With this combination of transceivers the frequency coverage achieved is from 80m to 3cm; however in reality most portable operation centres around eight (8) bands from 6m to 3cm with the HF section dedicated to specific Field Days. While the most common mode used in this portable station is SSB, CW is available across all the bands, with FM capability being available from 6m to 23cm independently of the SSB Transceivers/Transverters. The YAESU dual band FT-8800R offers further flexibility by functioning as a repeater.

When operating in the Microwave region of the frequency spectrum, frequency accuracy becomes an issue. To ensure that all the transverters are as close to frequemcy as possible, each transverter is locked by a GPSDO (GPS Disciplined Oscillator). This ensures a Maximum frequency discrepancy of +/-50Hz across the frequency range. This unit is described else where in this blog.

Signal routing from the central console is the next area to be considered in the “Block Diagram“. This process can make or break a portable station. In many cases the number of feed lines that are connected to the antenna farm can be a “nightmare waiting to happen” when trying to setup a portable station quickly or for that matter working out whether all the transceivers are connected to the correct antenna.

In this portable system every feed-line is labelled at each end of the cable. In addition where there are antennas that work on multiple frequencies, all the combiners (diplexers / triplexers) are positioned at the centre console thus limiting the number of coax runs.

In the case of the transverters, instead of running separate IF feed to each transverter, a relay switching tree has been developed that is located on the mast near to the transveters. This relay tree has its remote head positioned in the centre of the radio console. A simple turn of the central knob routes the signal to and from the required transverter. The only change over switch that is separate from the radio console switches the HF Vertical antenna to the HF Tri-band beam. This switch is mounted in a separate switch box.

In the case of the GPSDO, a common feed is routed to the mast and then a passive splitter is used to direct the signal to the transverters.

The Antenna System used by this system is self explanatory except for the “squid pole” vertical. Many people use this style of system for HF, however what was of concern in the assembly of this portable system was the method used to ensure that the “squid pole” remained vertical and that the setup time was minimal. What was needed was some form of screw in base that didn’t require driving large stakes into the ground. The solution turned out to be quite simple. A visit to the local hardware store uncovered a tube assembly with a tapered lower section that had a course external thread. This device also had a number of concentric bushes that acted as reducers in the top that turned out to be just ideal for the “squid pole”. As if this was not enough there was “more”; it came with a piece of reinforcing rod that provided a way to screw the whole assembly into and out of the ground. What was this device indented for? Assurances were received from the salesman that this device was a “Beach Umbrella stand”!

The last area of the “Block Diagram” relates to the Computer control of the transceivers. This achieved by building three interfaces that connect to the laptop computers USB ports. These interfaces allow complete control of the YAESU FT-817ND’s and the ICOM IC-7000 and add a great deal of flexibility to the total operation.

Thank you for the emails asking how the portable station equipment was interconnected. I hope this article has addressed most if not all of your questions.