Getting mobile again on the 70MHz (4m) Amateur Band

My 4m Band History To Date

In my radio shack I use an ICOM V200T PMR (Private Mobile Radio) rig, putting out around 30W, for my 70MHz or 4m radio activity. I have a professionally manufactured Jaybeam folded dipole above the roof line as an aerial. It is particularly good as it comes complete with a balun and is very well manufactured. I think I purchased the aerial in 1990 - and it has served me well ever since.

I have other PMR rigs in the cupboard - as I used to be very active and enjoyed converting many of them to the Amateur bands. I started using the 4m band in 1989 using a crystal controlled Telefunken radio which I converted from a German Fire Engine - as they were moving away from crystals and on to VFOs (Variable Frequency Oscillators).

It has, however, been about 4 years since I have had a 4m transceiver, or 'rig', in the car and, as the band seems to be getting more popular in this part of the UK once again, I thought it was time to put that right!

Of course, the one 4m remote-head rig I already owned was limited to 20W and had an annoying 90 second time-out timer, which I could not reprogram, so I wanted to use something with a bit more power out! I still have my Pye 4m amplifier but I wanted to cut down on space and wiring in the car - especially as a modern car can be less roomy for all that gear.

A Solution For Mobile Operating

In the UK it is possible to purchase a 'Quad Band' transceiver covering 4 Amateur Bands: 6m, 4m, 2m and 70cm. I purchased mine from the Martin Lynch Group in Staines, London.

This gave me a remote head option capable of running up to 50W of power out to the aerial. Such power would be just right for mobile operation!

It also means that I can occasionally use the 6m band from the car. I already have access to 2m & 70cm band (analogue & digital) from my ICOM ID5100E in the car. You can see the head unit of the ID5100E above the corresponding head unit of the Quad-Band radio in the photo above. This means both radios are very easy to operate from the driving position.

Now, how to power two radios from one heavy-duty socket in the boot of the car ('trunk' for my Stateside readers!) in a safe manner? Well, I am a great supporter of West Mountain Radio products and PowerPoles, so the top photo shows you the fused system I use to accommodate two radios running at the same time. 

The second photo shows the unit in situ, next to the main unit for the ICOM ID5100E radio. You can see the 12v socket clearly feeding the RigRunner. It works a treat!

Here you can see the 4m aerial situated at the back of my car. It is centre loaded, to make the physical height of the aerial smaller whilst maintaining the same electrical length. It works incredibly well!

I have already worked a few stations whilst travelling around Kent and I expect to work a more over the coming weeks.

Here you can see the 4m aerial on the left & the dual-band 2m/70cm aerial on the right - at the rear of my car.

Hope you found that interesting?

More later!

Best 73 de John G0GCQ

First Dry Run of Portable HF Station

Putting it all together in the rear garden

9m tall Prowhip aerial erected in rear garden ~ tunes on all the Amateur HF ('Short Wave') bands.

Solar panels charging sealed lead acid battery ~ Yaesu FT450D HF radio on white folding table.  

This is my 6-year old sealed lead acid battery ~ used as a spare as the leisure battery is being charged.

The solar panels are working really well ~ allowing me to run 100 Watts output from the radio. The battery is being topped-up as it is being charged at 40 amps via the solar panels. 

Front view ~ note aerial coaxial cable off to the vertical antenna. Cable is 24 feet long, which helps with the tuning process for the vertical aerial on Amateur Radio HF bands.

Yaesu FT-450D radio ~ using a Heil Hand Mic for good audio response & driving of the rig (to get high power output ~ closer to 90W on peaks).

Even though the bands were not very good, due to a recent solar flare that knocked out HF communication to some extent, the radio did pick-up many Italian & German Radio Amateur Stations.

Getting everything ready for portable HF operating ~ Part 2

Vertical Aerial

The Prowhip vertical aerial that I use is based on a fibreglass fishing pole which is less than 1.3m collapsed and 9m extended. Link HERE.

The aerial wire, shown here in red, travels up the fibreglass pole as you extend it to its fullest length. The wire is captured at the tip end, so no threading required!

At the bottom of the aerial you can see an UNUN ~ which allows an unbalanced piece of wire, as shown here in red, to join with a length of 50 Ohm coaxial cable to the radio, without the signal from the radio feeding straight back & frying it. This way, the aerial can be electrically tuned ('cut' to length electrically) using an aerial tuner ~ allowing the maximum signal to get out into the ether and around the globe :-)

Here, at another location from my own, you can see the vertical aerial fully extended ~ 9m ~ mounted on the aluminium post (shown behind the aerial in the photo just above this one). The coaxial cable feeds from the bottom of the UNUN to the rear of the radio.

Yesterday, at this location, I was able to tune the radio on all the HF ('Shortwave Bands' = High Frequency) bands that we can use, including the additional 6m band (50MHz) that we have access to here in the UK.

Stations worked included one in the Azores on the 20m (14MHz) band, which was not particularly 'alive' as conditions were electrically noisy (recent Solar Flares).

I am very happy with this aerial & await using it further this Summer :-)

Yaesu FT-450D HF Transceiver

This is the transceiver that I intend to use whilst out and about working HF portable. It is a very good (smallish) size, whilst maintaining good ergonomics, power and facilities. The internal tuner works very well with the vertical aerial mentioned in part 1.

I will be writing more about this little gem another time.

That's it for now :-)

73 de John G0GCQ