EA5ON Mobile station

UPDATE 25 MAY 2014

After trying out the Tentec Eagle and the Kenwood TS590 in the car, I decided to replace the TS850S after years of sterling service. I now use the TS590 and am very happy with it.

Also, MFJ bought out a 17' version of the telescopic whips and that's what I use nowadays on 20 through 6 metres. The part number is MFJ 1979


I'm frequently asked what I'm using in the mobile so here's a quick look! Further down the page there's more info about my mobiling activity.

The radio

I currently use an old Kenwood TS850S in the car:

The amp

is an Ameritron ALS500M:

The antenna

is a bit of a mix. If you have 5 minutes to spare, check out the video of the antenna system at :

Otherwise, at a glance it looks like this:


I started mobiling in 2000, and published an article in CQ Magazine about my experience after my first year of mobiling (link to follow soon for the spanish version....does anyone have a copy of the english version?)

Why a Kenwood TS850S?

This is a BIG rig! If you are wondering why I would choose to use such an old beast in my car, the answer is mostly to do with it's good IMDDR (Intermodulation Distortion Dynamic Range) performance. I have used many different radios to a greater or lesser time in the car and generally speaking, all of the small modern HF rigs have receiver limitations. I've used the Kenwood TS50, TS130, TS140 and TS480, Icom 706 and 7000, and Yaesu FT817 and 897. All of them have the same problem, they were designed to use small antennas and not the full size antennas over salt water that I use. The only small rig which did not have this problem was the Elecraft K2, a bulletproof receiver but sadly, a really poor SSB transmit audio and a bit of a quirky rig to use. You can find out more about receiver performance at http://www.ea1ddo.es/radios.html

A couple of new rigs appeared on the market in the last year or two which may give the same or even better performance, one is the mid-sized Kenwood TS590S and the other, the Tentec Eagle. The Elecraft KX3 is also worth considering.

Although receiver performance is important, its not the be all and end all of a radio. As I already mentioned, in spite of the excellent receiver on the Elecraft K2, the transmitted audio was just not great. When mobile, there are things that are a bit more relevant than at your house. How easy is it to plug in and out, for example, if you want to put your rig away after use? The new 4 pin molex plugs used by a lot of the newer radios are a right pain. The 8 pin plug on the TS850 amp line is a tight fit and sure won't last long. And how difficult was it to solder that silly mini-DIN plug for the Kenwood 480? And what about displays and visibility? I love the fact that on my Icom 7000 I can read SWR, RF power, compression, and ALC, all at once. But if the rig is at an angle, or it's sunny, I can't see a blind thing! Much better are the backlit LCDs for this job, like the IC706 and Kenwood 480. Think about ease of use. How easy is it to use the menu system on the mini Icom and Yaesu rigs? This is maybe a personal thing but I find that I can usually end up finding what I want on an Icom without needing to consult the manual. Not so with the Yaesus. The Kenwood 480 again came up trumps here, with a front panel with everything at your fingertips using dual function keys (press once, or keep pressed for 2 seconds). All the keys I wanted, with no superflous funtions. But for me, the split head design of the 480 killed all of its plus points, it just doesn't fit in with my "modus operandi". And all of this without taking into consideration the cost factor. New rigs like the 7000 have IF DSP filters and don't need add-on narrow crystal filters, nor voice keyers, an important consideration if you want those features.

In short, the perfect mobile rig doesn't exist. Or if it does, I haven't found it yet.

How do I feed the amplifier?

This is another frequent question I get asked. In a perfect world, the amplifier would probably run off a separate battery, connected up to the alternator in the car. When I first got the amp, about 10 years ago, I tried wiring it up to the main car battery. This 80 Ah battery with the stock alternator was just not sufficient to run rig and amp and you could hear the engine and alternator struggle while transmitting. So, I decided to put the amp in the back on a seperate 100Ah battery but not connected to the alternator. This system is very simple, you just take the battery out at home and charge it on a conventional charger. The negative part is that battery can deteriorate if you run it down too much and will not hold its charge. Also, these high power low voltage solid state devices are very voltage sensitive. The ALS 500 is designed to give full power (around 500w pep) with 14VDC. Power will drop around 50W per volt. When a car battery is connected to an alternator and the engine is running, output is nominally 13.8V, but when used on it's own will only give 12V when fully charged, and reducing as the battery is used. This means that the most I can get out of the amp is around 400w and often a bit less. In practical terms though, the extra 100w are almost unnoticeable.

Recently I looked around to see about possible replacements for the ALS500 but nowadays there is no real alternative. The best option is perhaps the Tokyo Hypower HL450, or, if you are prepared to sacrifice operation on the WARC bands, the HL700 should give around 600W pep.

I recently spoke to a Belgian station who runs more than 1KW in his mobile, using a home made amp. He told me that over 500W, you have to start thinking about using 50V systems, and that if he were to start over again, his choice would be to install a 48V power system in the rear of the car and use an Ameritron ALS1300. Food for thought for my next car!

Antenna considerations

My first mobile antennas were the "Eco Veicolare", similar to the hamstick antennas. They worked pretty good on the higher bands and I would not hesitate to recommend them for anyone who is looking for a cheap and cheerful solution to getting started on HF mobile. They fit nicely in the back of most cars, offer not too much wind resistance for using while driving, and give a pretty good account of themselves on the air. Like all short antennas, low band performance is marginal, but from 20 through 10, they are OK.

For cheap and cheerful though, I think its pretty difficult to beat the system I use at the moment, at least for using while parked. MFJ recently introduced a larger telescopic whip, 17' long, and this should mean being able to get full size performance on 10, 12, 15, 17, and 20 metres for a reasonable price. They are not perfect, sure there is some extra resistance creeps in with the way the sections connect together, plus they do not last forever (I'm on my fourth one in ten years now) but taking everything into consideration, I'm very happy with them. They say the proof of the pudding is in the eating, and with 302 countries worked from the mobile, I reckon that's proof enough.

More information

As far as I'm concerned, the best web page by far and away for mobile hams is www.k0bg.com . This is a real mine of information about all things HF mobile and thoroughly recommended. Alan is a very helpful guy too and in case you need something that's not on the page, he is always happy to help.


Vit Phoenix said...

TNX for mobile qso! 73! de UR5AVL

Duncanito said...

My pleasure Vit! Hope next qso will be Mobile to Mobile :)