Range of an ICOM A3E

Graeme Bird · Post by **Graeme Bird** » Wed Jul 23, 2008 11:09 pm

What range should I expect from an ICOM A3E handheld with an external antenna in my C42? would it be much worse than a built in NAVCOM unit?
I cant get Farnborough LARs from much more than 15 nm at 2000ft, or London Information from the south coast or Lille from mid channel.

Maybe I should change the antenna, there seems to be little info except that its 50ohm, no VSWR etc. Maybe its best with its own antenna mounted externally. or maybe the ground plane isn't good or big enough. The power is supposed to be 5W Peak envelope and 1.5 Carrier Wave, any suggestions ?

I guess I could change cable and antenna but to which antenna?

All comments appreciated
Graeme

tnowak · Post by **tnowak** » Thu Jul 24, 2008 8:11 am

I suggest a combination of improvements will give you increased range:
1. Use lower loss coax cable from Icom to antenna (as short a run as possible)
2. Ensure groundplane is as large as practicable
3. Invest in a better comm antenna instead of the stub antenna you now have
4. Ensure the antenna mounting is in an optimum (external) location.

I would suggest you could at least double your range if you adopt these improvements. Mid channel to Lille is a reasonable range; if you have difficultly raising Farnborough LARS from around 15NM then it may be an issue with antenna position/airframe screening effects.
TN

Graeme Bird · Post by **Graeme Bird** » Thu Jul 24, 2008 9:59 pm

Thanks for the advice, the antenna I have is a combined VHF, GPS, GPRS car like thing, I wonder if its designed to receive only. I have taken it to bits to make sure I am connected to the right port (just three wires coming out) and I am. Its like a carbon rod whip about 400 long, not long enough for 1/4wave at 118 MHz. I am in the process of buying a bob archer sa-006 folded dipole type - maybe someone has experience of these, they should be better in a GRP plane maybe?

Graeme

Ian Melville · Post by **Ian Melville** » Fri Jul 25, 2008 6:25 pm

combined VHF, GPS, GPRS car like thing

I would expect a device like this to be a compromise. Get a proper antenna for the VHF and a separate one for the GPS. I assume you are not going to use GPRS in flight

bob archer sa-006 folded dipole type

I doubt that this is a folded dipole, as they have 75ohm impedance, not 50 that you require. A very quick search found that it is "folded up", which looks to mean that it is shortened by shaping it into an S. Reception may be better than you current installation, but it will not be as good as a straight vertical dipole, or a whip with a ground plane.

Are you trying to keep it out of sight?

Ian

tnowak · Post by **tnowak** » Mon Jul 28, 2008 1:18 pm

I am not that familiar with the C42 but a quick Google search says the primary structure is aluminium covered with composite sheets. That sounds "similar" to my Vagabond - steel tube structure but covered with fabric instead of composite.

I get excellent radio performance with my wideband (118-136MHz) VHF comm antenna mounted on an aluminium root end fairing. I would imagine that solution would be simpler and cheaper for you than the folded dipole. Just make sure you attach the folded dipole in the correct orientation - VHF transmissions are vertically polarized which means your antenna needs to be vertical (ish).

I think the antenna you were using was your problem. Antennas that are built for a very wide range of frequencies are always a compromise, performance-wise.
TN

Steve Brown · Post by **Steve Brown** » Mon Jul 28, 2008 2:00 pm

My home made comm antenna is a 20.3" long x 0.5" wide self adhesive copper foil tape stuck to the glass / foam vertical stabiliser with another identical 20.3" long x 0.5" wide copper foil vertical strip that lays horizontally and hence at right angles to the former.
Three ferrite baluns are placed/shrink sleeved on to the co-ax where it meets the foil strips.

The centre conductor is soldered to the vertical foil and the shield to the horizontal one. All potted in epoxy & a layer of glass covers the foils.

Fantastic range & reception, cheap and drag / damage free

Will Greenwood · Post by **Will Greenwood** » Thu Jul 31, 2008 9:55 pm

Hi Graeme, why not give ICOM UK a call, I flew to Maypole(PPR) in Kent today to get a radio fixed. They picked me up, did the work and dropped me back to the strip, where he installed and checked the radio and off I went. The price was good, and the service !!
Ask for Geoff or Chris 01227 741741.

Regards Will.