Saturday, March 18, 2017

Experiments With Yaesu Fusion

We now have four stations in Galway operational on Yaesu Fusion. 3 have FTM400XDR transceivers and the other has a FTM100. Two in Mayo should be on shortly so the efforts have finally borne fruit. Possibly another FTM100 in Galway shortly. There is another operator who ownes a Yaesu FT991. Nine on the air in a short time is a great effort.

The Limerick area, due South of Galway,  have a Yaesu Fusion Repeater which provides a good signal throughout Galway and into Co. Mayo as far west as Westport. The current number of Fusion operators in the Limerick area would appear to be around ten or eleven.

Plans are to place a Wires-X gateway online by the end of April, which will serve Galway City and the surrounding area of 25 Km radius.

The first experiment was carried out between EI3FEB in Headford and myself in Galway City - a path of 23.5 Km but it had a few hills in between the two stations so was a poor path at the best of times. The path was chosen as this was probably the worst signal strength achievable.

Both rigs were set up to transmit 5 watts and the initial transmission was made on FM 


As can be seen on the display the signal strength did not even register and the FM signal had the usual hiss encountered with FM signals received on the fringe area. For an S0 signal it was not too band. The FTM 400 recorded the returned signal as S0.5 - S1. Readable with plenty of hiss. Note the FM displayed to the right of the frequency displayed indicating this was in the FM mode. The lower green light indicates FM reception.

The mode was changed to C4FM and the signal received was most impressive 


This signal was still received at a S0 level but his time in C4FM. The quality of audio was crystal clear with absolutely no background noise. Note the DN displayed to the right of the frequency displayed denoting in digital mode. The blue light denotes the reception of a digital signal. When the digital signal is received other information is embedded within it which includes the Callsign and also GPS coordinates. The distance as shown was derived from that information.

Check out the YouTube video  https://www.youtube.com/watch?v=I90774lrNvU
Quite impressive with  no R2D2 sounds from the received signal.

More to follow   ..........................

Saturday, February 4, 2017

Yaesu Fusion

Yaesu Fusion has been established in the West of Ireland by the Limerick Radio Club on both 2 metres and 70cms. The Limerick Repeater has been operational on System Fusion for over a year and more recently the 70cms Repeater has been installed. Wires-X is not connected so the Limerick Repeaters are specifically just acting as Repeaters and not able to connect to the rest of the world. Donegal also has a Fusion Repeater and this is connected to the Wires-X system. 

Yaesu Fusion radios are Dual Band and Dual Mode which makes them more versatile. As a result it is possible to experiment with direct point to point simplex communication. Regrettably not a lot of individuals have the equipment as yet and there are also rival modes like DMR and perhaps the older D-Star.



The DV4Mini set up for Yaesu Fusion

Using a DV Megga Bluestack or a DV4Mini, it is possible to connect into some of the many Yaesu Fusion Talkrooms. There a huge number and each area of the world has its own designated area or indeed some common or shared areas.

Of late there has been a number of talkrooms linked together in the UK resulting in a huge increase in activity in one particular area. It has even been possible to cross conect from DMR to Fusion a vice versa. Sometimes up to 80+ have linked ot this area.



A screen grab of a busy Yaesu Fusion Talk Room from the DV4Mini Control Panel

So far there have been no Fusion contacts on the Limerick Repeater despite a number of E-mails requesting a sked to try the system out. The transmissions do go through the Repeater without any problem but alas no replies.Undoubtedly this area will increase in activity as more become involved.

The initial feeling is that Yaesu Fusion does have better quality over the other modes. Most of the equipment is dual band so there is an opportunity to work through more repeaters and gateways. Fusion does lend itself to more point to point simplex communication on both 2 metres and 70cms. Repeater and gateway activity may also promote this mode.

The Disadvantage with Fusion is that it is a propriety mode and cannot be copied by any other company other than Yaesu. DMR may possibly become more popular with the number of cheaper Chinese tranceivers and handhelds. DMR is more of an open source mode and not confined to any one manufacturer making it more attractive. A bit like Betamax and VHS - which standard will ultimately win. It is possible that there are still other Digital systems that have not yet been released.

The Multimode Digital Gateway

Consideration was given to building up 2 metre Echolink Gateway but with the times that are in it, it seemed more logical to go digital instead. There is an interest in Digital Communications in the Galway/Mayo area and plenty of opportunity for experimentation.  To Date Joe EI3IX, John EI7AB, and myself seem to be the only ones active on the Digital Voice Modes although there are two more registered in the DMR listings locally.

A number of ‘Homebrew’ DMR Repeaters have been built using various commercial hardware, but powered by the MMDVM modems so this set up seemed to be the best choice.  The ‘modem’ package is made up of an Arduino Due micro with a ZUM MMDVM modem board as the front end, and a Raspberry Pi-3 running the MMDVM Host software. The software is written by Jonathan G4KLX a well know author of D-Star software. This system was recommended by John Anderson, MI0AAZ, who has been instrumental in setting up many Repeaters and Gateway systems in Northern Ireland.


The MMDVM Board

Raspberry Pi and associated software is not really my area of expertice. Not being all that computer literate, it was a good decision to seek assistance with the programming. With the aid of Team viewer and John, MI0AAZ at the other end, it was possible to configure the Arduino Due board first. This was not overly time consuming and I could have been talked through that part. The configuration of the Raspberry Pi was different. It was great to be able to watch and have each step explained as the set up progressed. None of the quickness of the hand deceiving the eye where one learns nothing.

The MMDVM image was written onto a 16GB SD Card and plugged into the Raspberry Pi. The Arduino Due was plugged into one of the USB ports of the RPi and then the power applied to the RPi. LEDs came on but seemed to be static. It was necessary to find the IP address of the Raspberry Pi to connect the laptop to the system. A remote connection was made to the Raspberry Pi after a few attempts and the system screen appeared on the laptop. It wass from here that the configuration took place. 

A number of updates to the software were performed and then the system configuration file was updated with my information. it is important to go through this section with a clear head. The connection to the network is wholly dependant on this file. All details such as the callsign, DMR number, and location need to be entered here. The different modes of operation were entered here also. In my case D-Star, DMR and Yaesu Fusion.

The Raspberry Pi, was connected to the internet and it auto booted into the program. On checking the Brandmeister Dashboard it was found that the software had connected and both DMR and Fusion servers and showed no errors. D-Star required another registration number and this had not come through at the time and so was not included.  Initially the setup was performed via an Ethernet Cable but, on completion, the system is totally operational via WiFi connection from the shack. Once operational there will be a large MMDVM sign above the Transmitter symbol in Galway. Some further registration has to be performed with the Gateway's Callsign before this can happen.


The First Connection from EI is shown in the Galway Area

The complete system is shown below and there is very little to do until the Callsign comes in from ComReg. This should be fairly fast as there has been communication seeking payment for the Licence by our Regulator.


The complete setup showing Motorola GM350, Arduino Due and Raspberry Pi

Programming the GM350 requires an interface cable and Motorola programming software which I don't posess but it will only require a short journey down to a friend in Oak electronics to make this transceiver work with the correct parameters.

The Brandmeister Network seems to have a large number of Repeaters and Gateways connected and checking the Dashboard will reveal the status of all the connected hardware. Looking at the activity map, will give real time checks of the hardware connected.


Brandmeister Activity Map

Some DMR sets have APRS fitted and it is possible to see your own location appearing on the map in a similar way to APRS. Fi. This map shows the location of all hardware connected around the world. There are many other functions associated with the Brandmeister Dashboard such as a worldwide listing of Repeaters and Hotspots along with their associated heard lists. This can be a useful visual indicator for test puproses. It does save having to do things like Echotest which only serves to jam up the network unnecessarily.

Update:
I have word that I should be getting the Callsign for the Gateway in the next week or so and this project will be up and running in a very short time SO now is the time to get the Motorola twaeked up and ready.

Friday, December 2, 2016

The Digital Bug Continues


Having gotten the bug for Digital Voice operation and the obvious way to go on VHF or UHF is via one of the many modes available of late. C4FM, D-Star, or DMR - Which one?

C4FM

They all have their attributes but in order of complexity the C4FM seems to be the first choice and easy to set up. The mode is more modern has a lot going for it and any signals heard seem to be of great quality. There is a C4FM repeater in my locality, located in Limerick. There is nothing for other modes. A DV4Mini access point would be an ideal soulution to hooking into a network which will give me contacts. A bit like a complicated EchoLink all the same. I have my mind set on purchasing a FTM-400XDR which has all the facilities on it including APRS.


This rig is analogue and C4FM  and also has built in GPS for APRS operation. Strangely a handheld is quite expensive for this mode of operation so probably better to get the mobile rig and done with it. I was never a huge fan of Handheld operation.

Strangely one has to register for a DMR I/Dnumber so as to set up a Hotspot such as a DV4mini or DVMegga system. Not a complicated situation but it is necessary to scan in the front page of the licence as proof that it is you applying.

DMR

Slightly more complex to set up  and I/D number is required which obviously links to the Callsign. Code Plugs are required. Programming isn’t too complicated once you understand the concept of Slots, TalkGroups and Zones.  All of these parameters have to be programmed into the code plug. Perhaps it is best to join a local group in the area who will have a downloadable code plug which is far easier.

A code plug is simply a radio's configuration file. Using the Manufacturer's programming software, it is possible to configure the channels and operating parameters of the radio. This file is uploaded to the radio and should be saved on the computer as backup. Downloadable codeplugs from local user groups are probably the best way to go.

An excellent bargain was found on Amazon.com  The Zaston D900 handheld x 2. At the price shown they were perfect for experimentation and did not break the bank. A handheld, but it is an entry level into the area of DMR. The offer only lasted a couple of weeks and the batch was sold out and then reposted for a larger fee. He who hesitates is lost!



I was informed that these are a clone of the TYT MD-380 and with a Firmware Update and a local Code plug these will be more than enough to get started in to DMR. In the box, there are two handhelds, 2 chargers, a programming leads and an "Agent Smith" (Matrix) style microphone and earpiece. One does not have to use this arrangement.

Straight out of the box, it was possible to use the rig as the battery had a good charge. The Handhelds are of sturdy construction and the audio output is of excellent quality. A code plug with mainly Northern frequencies and Simplex channels was downloaded. After a bit of a struggle the rigs worked perfectly. The problem was a small error in the codeplug which was not compatible with my Hotspot. After some head scratching advice was sought and the problem rectified. Results were impressive.

Access Points

The DV4 mini is a small USB dongle working on 70 cms and provides a great starting point for Digital communications. The Raspberry Pi is linked via Wi Fi to the laptop where the control panel is displayed.


A DVMegga Bluestack dual band access point was subsequently puchased which is more versatile and stand alone. This has been in constant use with no problems encountered. This system is uses the Wi Fi from an Andriod tablet or mobile phone linked via bluetooth. The Android phone acts as the control panel although not physically connected. It is stable and the quality of signal is excellent.


The system works well with DMR and Fusion although D-Star has not been tested - there are limits! The new software is due out in 2017 and this will facilitate cross-mode connects e.g. DMR to Fusion etc.

Local Gateway/Access Point

I have recently procured the components for a triple mode gateway to allow access to D-Star, DMR and Yaesu Fusion. It will be made up from a Raspberry Pi, Arduino Due, an MMDVM board and a Mororola GM350 with minor modifications. Pictured below is the MMDVM seated on the Arduino Due which will connect to the Rasberry Pi.


The licence has been applied for at this stage so it is a matter of time before the go ahead is given. VHF was chosen as the range would be be better as opposed to VHF. We should be able to cover a 30 mile radius.

At least a start on the software has been made and construction which will get the system on air reasonably quickly. I think better to deal with project myself as the VHF Group Repeater is still waiting to be located on site after 3 years. Left to others, nothing gets done as there is not the same enthusiasm!

Friday, November 4, 2016

Adventures on Digital Voice Using the ARD9000MK2

An ARD 9000Mk2 was purchased some years ago at the same time as the Yaesu FTDX5000MP; a present to myself on retirement. Early experiments included recording the transmitted output onto a tape recorder and playing this back through the unit to hear the results. It worked fine. A second unit had been found at a rally and it was snapped up for a mere 20 Euro - a bargain. Until recently, nobody had ever been worked or heard on digital voice irrespective of the number of times the rig was left monitoring a supposed digital channel on any of the HF bands.


The ADR 9000MK2

The AOR Corporation were the first ham manufacturer to introduce a Digital voice "modem" in 2004. Their first unit was the ARD9800 which had the ability to transfer files. The ARD9000 was produced without the ability to transfer files and was a voice only unit and a little cheaper to purchase. The design of this unit was based on a VOCODER (voice encode and decode) protocol designed by Charles Brain G4GUO. His protocol involved the use of Advanced Mulit-Band Excitation (AMBE), a propriety speech coding standard developed by Digital Voice Systems.

The specifications of the ARD 9000Mk2  are as follows:

Modulation method:   
                                   Orthogonal Frequency Division Multiplexing (OFDM)
Bandwidth:                   300Hz - 2500Hz, 36 carriers
Symbol Rate:               20mS (50 baud)
Guard interval:              4mS
Tone Steps                   62.5Hz
Modulation method:
                                   36 carriers: DQPSK (3.6K)
AFSK                          +/- 125Hz
Error Correction:           Voice: Golay + Hamming
Hearder                       1 Sec. 3 Tones + BPSK training pattern for synchronisation
Digital Voice:                AMBE coder, decoder
Signal Detection:          Automatic Digital detect. Automatic switching
                                   between analogue and digital mode.

Description and Theory 

There are a few common elements to a digital voice system. The Modem converts a signal from the microphone, or another analogue source, to a digital bit stream. This is referred to as an A/D converter. This is driven by an algorithm referred to as a CODEC. The signal is then processed into a modulation waveform that can be applied to a radio transmitter. The received signal has to be converted to a digital stream e.g. demodulated. The digital bit stream is then demodulated to form an analogue waveform via a digital to analogue converter by a matching algorithm or CODEC to that applied to the transmitter. The resultant signal can then drive a speaker. This is the basic function of the ADR 9000MK2.  See diagram below:


 The basic blocks of a digital voice modem

OFDM is a form of multicarrier modulation. An OFDM signal consists of a number of closely spaced modulated carriers. When modulation of any form - voice data etc. is applied to the carrier, the sidebands spread out either side.

On analogue modes, it is necessary for a receiver to be able to receive the whole signal to successfully demodulate the data. When signals are transmitted close to one another, they must be spaced so that the receiver can separate them using a filter and there must be a guard band between them. 

This is not the case with OFDM. Although the sidebands from each carrier overlap, they can still be received without the interference that might be expected because they are orthogonal to each other. This is achieved having the carrier spacing to the reciprocal of the symbol period.



Traditional view of receiving signals carrying modulation


To see how OFDM works, it is necessary to look at the receiver. This acts as a bank of demodulators, translating each carrier down to DC. The resultant signal is integrated over the symbol period to regenerate the data from that carrier. The same demodulator also demodulates the other carriers. As the carrier spacing equal to the reciprocal of the symbol period means that they will have a whole number of cycles in the symbol period and their contribution will sum ot zero - in other words there is no interference contribution.


One requirement of OFDM transmitting sytems is that they must be linear. Any non-linearity will cause distortion amongst carriers as a result of inter-modulation distortion.  This will introduce unwanted signals that would cause interference and impair the othogonality of the system.

Advantages:

Immunity to Selective Fading: One of the main advantages of OFDM is that it is more resistant to selective fading than single carrier systems as it divides the overall channel into multiple signals affected individually as flat fading channels 

Resilience to Interference: Interference appearing on channel may be bandwidth limited and will not affect the sub-channels. This means data will not be lost.

Spectrum Efficiency: using close spaced overlapping sub-carriers, a significant OFDM advantage is that makes efficient use of available spectrum.

Disadvantages: 

Hight peak to average power ratio: An OFDM signal has a noise figure like amplitude variation, and has a relatively large dynamic range, or peak to average power ratio. This impacts the RF amplifier efficiency as the amplifiers need to be linear and accommodate the large amplitude variations and these factors mean that the amplifier cannot operate with a high efficiency level.

Sensitive to  carrier offset and drift:  Another disadvantage of OFDM is that is sensitive to carrier frequency offset and drift. Single carrier systems are less sensitive.

In practice

A number of settings need to be performed before actually transmitting on air.

Ensure that the receiver is actually 100% on the same frequency as the other user. IF necessary, once the QSO is established, use the RIT.

The I.F. filters on the transceiver need to be set to 3KHz

Ensure that Speech compression and equalisation is switched off

Bear in mind that the duty cycle of the transmitted signal is around 100% so set the carrier level to a suitable power output in accordance with the radio specifications. 

Establish the initial contact on SSB and ensure that the resolution of the voice is perfect and the TX and RX are on the same frequency. This is essential. 

Ensure that the ALC meter shows no movement. If there is movement, back off the input from the modem using the mic gain from the transceiver. If the modem is a bit "lively" reduce the pre-set mic input on the mic pot on the underside of the modem. 

When transmitting pay attention to the overdrive light on the modem. Back away from the microphone or reduce the input to the modem.The overload light should seldom flash and occasional flash will not cause a problem.

It is a good idea to run the ARD9000 off a different supply to that of the rig. A small Gel Battery was employed to be on the safe side. This eliminates the possibility of a hum loop. Ferrite beads in the power line and on the mic lead will prevent any RF getting into the box. Again all precautionary. This will ensure that any poor decode is only down to mic gain on TX or input levels at the RX end.

The Receive settings:

Ensure that the modem is not overloaded watch the Overload light on the Modem. If it is flashing, the input to the modem is too low. If it remains off the input is optimal. If it remains on the AF input level is too high. These levels are dependant on the AF gain from the transceiver. The unit has its AF gain control for personal preference either through the speaker mic or via a lousdpeaker.

Results to Date

Initial work was carried out on 2 metres FM. Both myself and EI7GMB had never used the units before so this was a steep learning curve. Following successful results on 2 metres FM, SSB was tried with surprisingting results.

Using the Kenwood TM-D710, the following settings were applied. 

FM modulation:    Wide
Mic Sensitivity:     Low
AF gain:              Set as required
 
The mic output pre-set found underneath the unit was reduced in gain slightly. 

Operation on FM

Surprisingly, this process was not painful. In the initial stages, everything broke up and the decode was erratic until levels were correctly set at each end. Everything came together quickly and 2 way communication was possible with comfortable decode. The reproduction of the voice was excellent and both sides achieved good results. A reduction of power between the stations was disappointing. When the carrier was not fully quieting, the noise was too great for the unit to overcome. This resulted in almost incoherent signals. Back up to a fully quieting FM carrier gave good results once again. 

A trip onto the Limerick voice repeater was made. The signal of the repeater was good on both sides of the transmission. The results were excellent from the digital signal transmitted through the Limerick repeater. The received signal was flawless. 

It was concluded that Digital Voice would be excellent over a good path on FM but not at fringe levels where the carrier is noisy. Mobile operation has not yet been tried but will be the next test on the agenda.

The problem with the FM is that the digital carriers are superimposed on the one FM carrier. If the carrier received over a distance is noisy then the whole signal breaks up. Conclusion that digital voice needs a quiet carrier to be received well. Digital is either there or not there. How does D-Star cope or any of the other digital modes? This would be interesting to observe the difference.

Operation on SSB

Connection to the Icom 756 tranceiver was simple and the operation required a few pre-sets to be made, for example, the microphone gain, the power level and above all observation of the ALC meter.

It was necessary to initiate the QSO on SSB and ensure that both tranceivers were on the exact same frequency.  If adjustment has to be made, once in the QSO,  use the RIT. This having been done the mic gain was increased to give about 30% power output and with care to observe the ALC meter. Whilst transmitting the overload LED was observed, ensuring that the signal did not overload the modem. 

The results were impressive and feedback via 2 metres proved that the signals were being decoded properly at each end. Reduction of power levels made no difference with a 5 watt level emanating from my own radio. The path was not too distant so this probably would have made no difference. This may be reduced further to see how the decode occurs with a weaker signal.

The results overall were excellent and the mode did everything it was supposed to do. Voice reproduction was similar in quality to FM and overall via SSB, the quality as good. 

SSB obviously allows this mode to come into its own. The 32 carriers were independent of a carrier as used in the FM mode. The modem captured the signal so much better and indeed as it was designed to do. 

There is no doubt that with care and attention, this mode is far better suited to SSB than for use on FM. 

The AMBE codec is the same as that used in D-Star, C4FM, and the commercial DMR. The unfortunate side, is that each mode employs a different protocol and none are compatible with each other. This results in a divided community. All the modes work perfectly within their own community. 

The fact that there are so many different digital modes will never allow one to take off in any great numbers. In Ireland, the ham community is small and there would have to be some standard to suit all. Would it be D-Star, C4FM or DMR at the end of the day. It is not going to be viable to buy one of each! With the AOR system, it can be interfaced to any radio whether on HF or VHF as it is literally plug and play. The Chinese manufacturers are beginning to take an interest in the digital market and will no doubt gravitate toward the DMR commercial standard as this would appear to be a more viable market with cheaper equipment. Hopefully they will not introduce yet another protocol.

This summarises the work to date, but if there are any other major developments, they will be added to this text.

Further information: It is wise to ensure that RF does not get into the set up. Ferrite beads of clip-ons around the mic lead and also the power lead may help. Experiments performed to date have used an alternative power supply to that used by the transceiver. This could be a small gel cell or a bank of NiMH batteries. The literature suggests that this is a good idea to prevent loops and any distortion being added to the signal.

Power levels: These have been reduced to 0.5W with no problem. Signals decoded well and the comparison to analogue was way different. The Digital still came out with 100% clarity and no background noise compared with the analogue signal  which was noisy.

YouTube link to results of a brief test    Click Here

Tests currently take place on 28.330MHz or 144.600MHz

References:
http://www.areg.org.au/activities-old/hf-digital-voice
http://www.radio-electronics.com/info/rf-technology-design/ofdm/ofdm-basics-tutorial.php

If there are any EI or UK stations using the AOR fast modem please drop me an E-mail as I would like to try a few contacts outside of Galway City.

Saturday, April 2, 2016

Kenwood VC-H1 Visual Communicator

Having got involved with the transmission of DATA over the airwaves, SSTV was bound to feature at some stage of the proceedings. After great success using MMSSTV and DM780's SSTV software on HF, it was apparent that this would be an interesting mode to use on VHF/UHF. It would certainly be more conducive with interference free pictures if used via the FM mode and better again it would be possible to send these via a Repeater if one really wanted to go from point to point. 

This does smack of Toys for Boys a bit, but in fairness, I could see the possibilities with our Emergency Communications Network and who knows where they may fit in. One very interesting application would be during the Galway Regatta where live feedback from the finish line would be a superb addition to the operation.  "A picture paints a thousand words".

My set up in the shack is very much tied to a desk top computer and obviously not geared for portable operation. Lap tops are a dead loss as they tend to be slow and very clunky and generally die at the most inopportune moments.

Enter the VC-H1 visual communicator manufactured by Kenwood some time ago during the 1990's. There are still a surprising number of these items out there either second hand and barely used or even still brand new and never sold.


The Kenwood VC-H1 Communicator 

Essentially the VC-H1 acts as a rather cumbersome Speaker Microphone when attached to a compatible handheld or the Kenwood TM-D700. To the left of its screen, the PTT and picture capture buttons are located.  The camera is located on the top of the unit and this can be swiveled for selfies, if absolutely necessary, or pointed in the direction of the subject. The 1.8 inch monitor screen is a little on the small side but is adequate for the majority of my needs. Received pictures can be stored in memory and can be re-sent to their originator. The pictures may be downloaded onto a PC if required. 

The transmitted and received pictures are sharp and clear and not too bad considering that they are received on such a small monitor. Images are transmitted from a  1/4-inch, 270,000-pixel CCD camera and seem to be good in most lighting conditions. The quality being about as good as a standard Web Cam.

The unit comes with a standard lead for connection into a Kenwood Handheld and this is also compatible with the Wouxun and Baofeng Handhelds. If used with these handhelds two modes are available in the form of Robot 36 colour, and Fast FM. If used with a Kenwood compatible handheld or the TM-D700 the unit is capable of operating the following modes in addition: Robot colour 72 , Scottie S1, Scottie S2, Martin M1, Martin M2, and AVT90.

Leads for this unit are expensive and very hard to come by especially the lead that connects into a PC and to the TM-D700. Of course if this lead is used the unit is extremely versatile as images may be uploaded and downloaded and the unit can be interfaced to a much more powerful tranceiver. 

Currently, the VC-H1 is being used to transmit pictures from the International Space station. Considering the distance travelled, the images are very good.




 Pictures Transmitted From the International Space Station

It is planned to hook this unit to the HF equipment although sending Selfies from the shack is really under utilising this type of equipment and I am not that vane! I would suspect that applications such as hill-walking and some of our outdoor activities may be enhanced with the use of this equipment.

Selling points

In addition to the detachable 1/4-inch CCD camera, the VC-H1 features a 1.8-inch color TFT (thin film transistor) type display. As well as viewing incoming pictures, you can review your own prior to transmission. The built-in microphone & speaker can be used in place of a separate speaker-microphone for your transceiver.

Up to 10 pictures can be stored in memory. This allows you to compare and pick the best shot to send. You can also store incoming pictures and protect them from unintentional deletion.

One of the great features of the VC-H1 is its ability to work with a personal computer. Hook it up to the RS-232C port on your laptop using the optional connection kit Microsoft Windows and you can save pictures (in JPEG format) that you send and receive. You can then cut and paste using standard graphics software, or even superimpose your own text. What's more, you can actually control the VC-H1 from your computer.

The Not so Good Points:

The unit requires 6 volts to operate and so is not great for mobile operation. It uses 4 AA batteries and these do not last too long with constant use. It does, however, work on 4 rechargeable AA batteries which is some consolation.

When you have bought one of these units it does become apparent that you need a second one if you want to get any fun out of it. It is no good relying on a friend to buy one or even hope that they will be on air if they do have one.

Interconnecting leads are expensive and as rare as hobby horse's droppings. The small connector into the unit costs more than 20 Euro. Any external leads have to be home-brewed apart from the lead connecting to the Handheld which they did include in the box. 


Lead wiring for TM-D700 and also for the PC

Sunday, March 20, 2016

Yaesu FT-707

Always on the look out for a good bargain, I saw an advert in the IRTS monthly news sheet for the FT-707. For the price it was an absolute steal as these rigs are much sought after by the QRP community. Following a chat on the phone with the seller, I discovered that the FT-707 had little use. I am normally fairly skeptical about second hand rigs, but I got quite a surprise when this one arrived. It was in pristine condition and had been well looked after BUT somebody had replaced one of the 10 metre sections with the CB band. Not too big a deal as it will be easy enough to replace the crystal and tune back to its original glory.


They really do not make rigs as sturdy as this nowadays. The received audio is rich and pleasant to listen to. From an operating point of view there are not too many knobs to twiddle and there are no extensive menu functions to set up. The Rig is supposed to run 100W PEP but realistically it will peak up to about 50W due to a design fault in the ALC. As can be seen from the picture the FT-707 covers 80 - 10 metres. There are a couple of mods to the ALC circuitry which will improve the performance but not deemed necessary as the rig functions well enough as it stands.

The receive side is good and has a "nice" sound to it. Obviously not the same as the modern day rigs with their digital filtering and DSP etc. but I don't really take this into account. 

The first few contacts made with the FT-707, on 40 metres, gave good reports both ways. The reception was good and a QRP to QRP contact made the day. 80 metres gave surprising results and I noted that there was a slightly better match on the antenna with a consequent increase in power. I got a 5.7. report from the News Reader, in Tipperary, and this was good considering the time of day.

A search around E-bay revealed the companion FC-707 ATU to complement the FT-707. Money burnt a hole in the pocket at this point. 



I found one that was in great condition and this complemented the appearance of the rig.The ATU only really tunes into a coaxial feed but is sufficient to get rid of any mismatch that will prevent the P.A. from putting out full power dues to it protection circuitry kicking in. It is quite sharp and has a wide tuning range and looks well built inside.

There was an external VFO and memory unit, the FV-707DM but I could not really see myself having any use for it. Many years ago Tom EI2GP had the complete set-up which came in an "optional rack" unit which made quite a tidy station.


A complete FT-707 Station stacked in the "Optional Rack"

I do not have the matching Power Supply unit for this rig but use the one that complemented the FT-107 instead as this is a little more sturdy in my opinion.