Elecraft Important Firmware Updates   February 26th, 2014

The following is an announcement from Elecraft USA.

The K3, KPA500, and KAT500 all have new beta firmware releases available. All three must be updated to take advantage of these major improvements to the KAT500 and KPA500. All known problems with unwanted re-tuning and faults have been fixed.
We’ve also added a new feature that allows the KAT500’s network settings to automatically track the K3’s VFO frequency. The K3 will send frequency information over the K3’s AUXBUS line, and the KAT500 will select previously memorized tuner settings as you move across the band, or when you “point and shoot” to work a packet spot.
If you have any difficulty with the instructions below, please post a question to the Elecraft list, or contact customer support.

Submitted by Peter Waters G3OJV

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Apach_Labs First with Pre-Distortion   February 25th, 2014

ANAN.100F

Greener and Cleaner!
Apache Labs become the first Amateur Transceiver manufacturer to include Pre-distortion technology within their PA’s for ultra-clean TX! ‘Pure Signal’ technology is available on all new and existing Anan products with a firmware/software update. Existing customers will be able to download the firmware update from the Apache-Labs website.

This new software system uses a method of introducing the distortion elements in a manner that enables the result to combine with the generated distortion and cancel it out. The net result is a much cleaner signal that is immediately obvious on a band monitoring scope. This all helps to reduce QRM and generally clean up the transmitted signal. This is seen as a huge development for the future of SSB communications.

The result is that your signal is “greener” and cleaner! This is even more important if you are running a linear, Peter G3OJV

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Phoenix FM

A couple of months ago I gave a talk to the Thames Amateur Radio Group (TARG) who meet on Canvey Island. One of the visitors that evening asked me if i would be interested in being interviewed live on his local radio station, Phoenix 98FM based in Brentwood Essex. I agreed to this and on Monday, 10th February, the interview was transmitted live. The interview took place on The Scott Ross Show which started at 1pm. The plan was to slot the interview in so that it would start immediatelyafter a couple of adverts and finish just before the news slot. This gave a 15 minute space into which the interview would be slotted.
It is a long time since i was in a local radio station, and I was of course interested to see how it all worked. Much of it is controlled by a couple of PCs that feed news and traffic information onto the screens, whilst another PC has a preprogrammed playlist together with timing indications. The CD player hardly gets a look in these days unless something crashes. Microphones are live or dead, simply by faders and the familiar “on-air” sign lights over the entrance door if the presenter is actually speaking.
The countdown to the interview came and with a pair of headphones on, I was ready for the start. This was quite straightforward, and although we had discussed some weeks earlier, the basic subject matter, it was unscripted. I did my best to give a balanced picture if amateur radio, as well as a plug for clubs and the RSGB. I was somewhat surprised to get an email back the following day from a listener in Canada who had been “tuned in” via the internet.
I have an audio file of this interview which some may wish to listen to and I have included a link to the file. Peter G3OJV.

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Screen Shot 2014-02-05 at 19.10.33

There is a growing trend for hams to purchase high power linear amplifiers, even though we are still stuck with a relatively low power limit here in the UK. A high power linear amplifier throws up a few potential problems for users. As soon as you move into this area of operation, you need to take a few precautions to avoid some pitfalls.

The most obvious one is connectors and cable. Never underestimate the much higher level of engineering, insulation and installation care that is needed to avoid welding connectors and cable together. And never underestimate how serious an RF burn can be if your equipment is not properly earthed and operated at near zero RF chassis voltage potential.These are all safety aspects. However, there is an interesting operational aspect that we have just started to notice.

A 600W amplifier probably runs at an input of around 1kW. That’s an AC mains drain of say 4-5 Amps. Quite easily handled by most domestic installations. BUT, step up to one of the currently available 2kW output amplifiers and you are in totally different territory. An OM-Power 2kW amplifier would draw at least 3kW of power from the AC mains. So there is around 1kW of power to dissipate (via an efficient fan) in the form of heat. That’s a lot of AC current to consider!

Your average domestic fan heater or electric radiator is quite happy at the end of an AC cable run because, if the current causes a voltage drop, it just delivers less heat. Nobody notices because there is nothing to indicate any drop. But in the case of a 2kW output amplifier, that voltage drop can be very significant to operation. It not only prevents the amplifier delivering its full power output, but can also throws up warning signals on the LCD display because the amplifier senses something is wrong.

This is something we are seeing now on a more regular basis. Some hams realise what is happening but others are jumping to the conclusion that there is a fault in their amplifier. So the rule here is to make sure that your amplifier has a short cable run directly to a properly installed wall socket, and not to a trailing cable extension lead or to a shack outside with a less than adequate cable run. Remember a 2kW amplifier will be drawing close to 13 Amps, the domestic maximum per socket. Apply ohms law and see how much voltage drop would occur on even a couple of ohms resistance.

To not follow these simple rule is to expect problems – unless you coast along at 400W output that is! Peter G3OJV.

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AOR AR-8600 MKII Receiver   February 4th, 2014

Screen Shot 2014-02-04 at 09.26.22

I recently took a look at the AOR-8600 MKII receiver, which has been in production now for some while, and I have to say that it is an absolute bargain. When you consider what you get for your money and the frequency coverage, it does represent excellent value.

Once upon a time a ham station had a separate receiver and a separate transmitter. Transceivers had not been invented. However, today the opposite is true with far less stations having a separate receiver. And I think that is perhaps not the ideal position to be in.

I often talk with hams who have a problem of one sort or another, and the ability to be able to monitor the transmission on a completely separate receiver is often desirable. There are some fault finding exercises that shorten the diagnostic time if you can listen to your own transmission. And of course as radio hams we like to know what is going on, on other frequencies.

I would suggest that the AR-8600 is the perfect monitor receiver for a ham radio station. It has a great performance, covers a very wide range of frequencies a and is small enough to fit into most stations

Below is the main specification just to remind you. For more information please go to this link.

Frequency range: 100kHz – 3000MHz
100 – 530kHz (not guaranteed)
All mode: WFM, NFM, SFM, WAM, AM, NAM, USB, LSB, CW
Two VFOs A / B
Memories 1,000 (20 banks x 50 channels)
Search banks: 40
Pass frequency: 2,000 (40 banks x 50)
Scan/Search rate: Approx. 37ch/sec max.
Tuning steps in multiples of 50Hz
* Airband 8.33kHz channel spacing
* 10.7MHz IF output port for SDU5500 * RS232 PC interface fitted as standard
* BNC antenna socket

Peter G3OJV.

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What’s The Connection?   February 3rd, 2014

KitKat_BBC

What exactly is the connection between a KitKat bar and a BBC announcer? And what possible connection has this with radio? Well I suppose that one could hazard a guess that this was a popular radio announcer’s snack. Possibly it was, but that would not be the right answer.

Today I was sitting with my wife in a Tesco store, having a cup of coffee, and as I opened the Kitkat, it reminded me of something that I heard on Radio 4 quite a few years ago. Kitkat was once a very important item in the training of BBC engineers.

One of the tasks that trainees had to carry out was to build a crude microphone in order to understand how it worked. For this they were supplied with a china mug, an elastic band, some wire and a Kitkat chocolate bar. The reason for this was that in order to make the microphone, the thinnest possible metal foil was needed and the cheapest and most readily available source was the inner wrapping of a Kitkat bar. That is the connection!

I assume they were allowed to eat the contents afterwards, and maybe some coffee in the cup. Peter G3OJV,

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MFJ-259B Swiss Army Knife   February 2nd, 2014

Screen Shot 2014-02-02 at 23.22.09

i have long been a fan of the MFJ-259B antenna analyser. I use it at home and we use it in our service department. It is an item that you have managed without for years, but once you own one you cannot do without it.

It is basically a very low power transmitter with built-in VSWR meter and impedance monitor. It covers 1.8MHz to 170MHz. That’s enough for most testing.

I can work ourside on various antennas and can couple the meter directly to the antenna whist I am adjusting it. I can check resonance and matching in minutes. I can even check for short circuits or open circuits and calculate the length of a piece of coax.

Recently we did some work in the show room and gpt the feeder cable muddled. A quick check with the MFJ-259B showed which feeder cable belonged to which antenna.

It really is the Swiss Army Knife for antenna work. Oh, and you can also turn it into a dip meter by adding a home made coil of one or two turns. Beat that! Peter G3OJV

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The Poor Man’s Linear Amplifier   February 2nd, 2014

Screen Shot 2014-02-02 at 21.26.21

Have you ever noticed that when you are watching TV, sometimes when the adverts are running, they can be louder than the program? Perhaps you have noticed on the radio that when listening to different types of music, some is louder than others. The same is noticeable between commercial radio stations. These variations are caused by the use of compression and form part of what is commonly known as the loudness war. Led mainly by pop records and advertising slots.

I suppose that in ham radio we also have a kind of loudness war, which is largely headed up by amplifiers and antennas with gain. It’s been going on for years. But you can achieve loudness benefits in ham radio without the using a linear or a Yagi. This is achieved by the use of compression and limiting. To my mind this is an area in ham radio that has not been properly explored, certainly in the mainstream of commercial ham radio transceivers.

Compression of a signal is not difficult to understand. Peaks of speech use the maximum level of energy in a signal, but everything else is down the level scale in a linear manner. This means that most of the information in a transmitted signal is way below the peak power, and some words transmitted via a 100W transceiver might be sent at a power level of 10W. That’s 10db below what they could be. If you doubt this, then look at your VSWR meter as you talk. In fact your VSWR meter is a good indication of your average transmit power. There is of course some inbuilt time lag, but it does give a general ideal of what is happening, or the laxk of a punchy and effective signal.

All commercial transceivers have ALC which basically works at RF and is designed to stop the RF power from being driven beyond a safe limit, but in practice the power setting of your transceiver. This is a very sluggish compressor but is the first stage in making good use of the potential of your transceiver. As your advance the mic gain control, you will begin to see the ALC level rise. You need to make sure that the ALC is operating on all levels of speech. This will help give slight compression on the signal and raise the average power output level.

Most modern transceivers have a separate compressor built in and it is here that a significant, apparent power gain can be achieved. There is an optimum setting between compression level and mic gain. As you increase compression level, you may find that is is advantageous to reduce mic gain somewhat, otherwise there is a risk of bringing up background noise. This does nothing for the the sound of your signal. It is claimed that 3dB of gain is available using the correct compression adjustments. That’s the same as doubling the power level. I would suggest that there is more than this to be had!

Firstly, it is very important to look at the audio response of the voice signal prior to any compression. As Bob Heil says, it all starts with the microphone. Get yourself a decent microphone like the Heil HM-12 or HMM. These have nice flat responses. Then spend some time investigating the EQ adjustments on your transceiver. This is designed to compensate for different voices. If you have a lot of bass then you need reduction at this end. Too much treble means adjustment at the top end. Often, a small boost in the mid range can result in more punch – i.e, a louder signal.

Unfortunately, the is a lot more to compression than is made available within a ham radio transceiver. Compression ratios are critical to getting the best results and so should ideally be variable. Also, the speed of compression and decay times are important as well as the inception levels All affect the final result and the “realised” gain. The best place for this to take place is outside of the transceiver using a dedicated mic amplifier unit ahead of the transceiver’s mic input. I would anticipate that with attention to all these variables, it should be possible to make a 100W untreated signal to come close to that from a 400W amplifier. Perhaps there is scope here for some small dedicated company in the UK to develop a unit. Yes I know that there are some systems already in existence, but not with all these adjustments. In fact the best solution would be in in software. Ah yes – back to SDR I guess! Peter G3OJV. Have you ever noticed that when you are watching TV, sometimes when the adverts are running, they can be louder than the program? Perhaps you have noticed on the radio that when listening to different types of music, some is louder than others. The same is noticeable between commercial radio stations. These variations are caused by the use of compression and form part of what is commonly known as the loudness war. Led mainly by pop records and advertising slots.

I suppose that in ham radio we also have a kind of loudness war, which is largely headed up by amplifiers and antennas with gain. It’s been going on for years. But you can achieve loudness benefits in ham radio without the using a linear or a Yagi. This is achieved by the use of compression and limiting. To my mind this is an area in ham radio that has not been properly explored, certainly in the mainstream of commercial ham radio transceivers.

Compression of a signal is not difficult to understand. Peaks of speech use the maximum level of energy in a signal, but everything else is down the level scale in a linear manner. This means that most of the information in a transmitted signal is way below the peak power, and some words transmitted via a 100W transceiver might be sent at a power level of 10W. That’s 10db below what they could be. If you doubt this, then look at your VSWR meter as you talk. In fact your VSWR meter is a good indication of your average transmit power. There is of course some inbuilt time lag, but it does give a general ideal of what is happening, or the laxk of a punchy and effective signal.

All commercial transceivers have ALC which basically works at RF and is designed to stop the RF power from being driven beyond a safe limit, but in practice the power setting of your transceiver. This is a very sluggish compressor but is the first stage in making good use of the potential of your transceiver. As your advance the mic gain control, you will begin to see the ALC level rise. You need to make sure that the ALC is operating on all levels of speech. This will help give slight compression on the signal and raise the average power output level.

Most modern transceivers have a separate compressor built in and it is here that a significant, apparent power gain can be achieved. There is an optimum setting between compression level and mic gain. As you increase compression level, you may find that is is advantageous to reduce mic gain somewhat, otherwise there is a risk of bringing up background noise. This does nothing for the the sound of your signal. It is claimed that 3dB of gain is available using the correct compression adjustments. That’s the same as doubling the power level. I would suggest that there is more than this to be had!

Firstly, it is very important to look at the audio response of the voice signal prior to any compression. As Bob Heil says, it all starts with the microphone. Get yourself a decent microphone like the Heil HM-12 or HMM. These have nice flat responses. Then spend some time investigating the EQ adjustments on your transceiver. This is designed to compensate for different voices. If you have a lot of bass then you need reduction at this end. Too much treble means adjustment at the top end. Often, a small boost in the mid range can result in more punch – i.e, a louder signal.

Unfortunately, the is a lot more to compression than is made available within a ham radio transceiver. Compression ratios are critical to getting the best results and so should ideally be variable. Also, the speed of compression and decay times are important as well as the inception levels All affect the final result and the “realised” gain. The best place for this to take place is outside of the transceiver using a dedicated mic amplifier unit ahead of the transceiver’s mic input. I would anticipate that with attention to all these variables, it should be possible to make a 100W untreated signal to come close to that from a 400W amplifier. Perhaps there is scope here for some small dedicated company in the UK to develop a unit. Yes I know that there are some systems already in existence, but not with all these adjustments. In fact the best solution would be in in software. Ah yes – back to SDR I guess! Peter G3OJV.

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SDR – But some hate Mice!   February 1st, 2014

Software Defined Radio has been around for a good few years now and most hams recognize the “SDR” abbreviation. It began life as an idea that was fairly easy to implement as a home brew project. The hardware needed was very simple and the main requirement was the dedicated software. There were plenty of software designers around, capable of producing workable programs, and so SDR was born.

But simple hardware only proved the system worked, it did not result in a performance level that could match an analogue system. And so the first commercial designs, with significant performance, began to appear, but not from the big names. They came from smaller, emerging communications companies and in some case, one-man operations.

Today SDR has reached new highs, and the performance is now matching or beating some of the best analogue designs. And yet the big names are still largely ignoring this technology. Or are they?

Many hams still need the tactile advantage of a total hardware radio. They will never be happy with a mouse. But, Elecraft have cleverly embraced SDR in the shape of the KX3. This transceiver has many of the advantages of SDR but in a conventional hardware package. They also provide the I/Q output, so that the radio can be used in conjunction with a PC or iPad. Other designs use some level of SDR, removing the need to use discrete IF filters. This processing is done within the firmware. Alinco have recently announced a hybrid transceiver that seems to offer the operator a choice of operation. But the “big three” are showing no outward signs of moving closer towards SDR.

As always, big manufacturers have to assess demand, and there is no doubt that we don’t at present have large queues for SDR equipment. But there are things that SDR can do, and that cannot be done by any other system, and this really is one of the driving forces of SDR.

Probably there is a place for both analogue and SDR in the same station. If I want to monitor the whole of 6m, waiting for an opening, I would certainly use SDR. For mobile – – absolutely not! Horses for courses as they say! Peter G3OJV

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