So its a pretty exciting time over here – a new radio has been acquired for my main QTH here in Australia – the Icom IC-7300.
The plan is to setup a remote station in Cambodia so I can work digital modes etc from VK. My previous main radio, the IC-7200, was originally purchased to take to Cambodia on my previous expedition, and when I go back in November I plan to leave it there – hence I needed a new radio for my shack!
So far so good, it is an amazing radio, and I will post a full review soon. So far, my favorite features are:
The Built in ATU. It will match 3:1 loads at 100 watts, or if the special ’emergency’ mode is activated, it will match 10:1 loads at 50 watts. This is perfect for digital modes such as JT65, where 50 watts is more than enough, and the 10:1 range is enough to match my 40/20M Fan Dipole on all bands above 40M! Efficiency suffers, but what a cool feature in a low end radio!
The built in band scope. Whilst a lot has been said about this, being the star feature and all, it is amazing how well it works. Not only is it incredibly accurate with no noticeable ‘birdies’ (a common problem with RTL-SDR based panadapters), but it also provides a very useful view of bandwidth usage in both transmit and receive. The audio scope is also amazing – you can quickly and easily see what transmit bandwidth the other station is using.
The extended transmit bandwidth. The IC-7300 can transmit from 100Hz to 2.9KHz. Whilst not the widest range, most radios in a similar price bracket only offer 2.3KHz of transmit bandwidth – not 2.8KHz. Naturally, you can lower the bandwidth if your chasing DX or don’t want to be considered ‘wide’.
The ‘Antenna Analyzer’. The IC-7300 comes with a neat little feature that lets you graph your antenna’s SWR performance across a band. Whilst it isn’t anywhere nearly as fully featured as a standalone Analyzer, its an interesting gimmick.
The Receiver. Whilst not the best receiver available, the IC-7300 is ranked pretty highly up in the Sherwood Engineering transceiver rankings. With IP+ off, it achieves a Narrow Spaced Dynamic Range (2KHz) of 81dB. With IP+ on, that figure rises to 94dB. Rob Sherwood recommends leaving IP+ off, unless needed. Also worth noting, is that Rob has previously stated that 80dB of dynamic range is more than enough for SSB work in most cases. In a nutshell, the IC-7300 is good enough for all but the most extreme contest enthusiasts. See more info here: Sherwood Engineering Transceiver Rankings.
There are many more great features, and I will cover them soon in an expanded / proper review. Let me know if there are any questions you’d like answered.
Even though I have a really modest station at the moment, over the last year I have been able to work over 100 DXCC Entities without too much difficulty. Today I though I’d share the details of my basic setup; hopefully to inspire other would be Hams or current Hams who don’t use HF to give it a go. The following gear is all you need to get your Basic Mixed DXCC (at least from Australia), and the total cost should be less than ~$1750 USD:
Icom IC-7200 Transceiver
Icom AH-4 Remote Antenna Tuner (a remote tuner significantly minimises loss in feed lines)
~5 Metres of 1″ Aluminium Tube (for element)
~100 Metres of 1.5mm^2 Wire (for radials)
1 Star Picket for the ground
Miscellaneous insulating material and a few hose clamps.
32 Ferrite Beads (for tuner control cable & feed line)
Coaxial Cable (I used Belden LL-195)
The Icom IC-7200 is a great value budget transceiver; it does everything a new Ham could want, and more. Some standout features are: easy to use IF DSP with dedicated knobs, built in USB for CAT & Audio (digital modes are easy to use), control for Icom AH-4 Tuner, rugged and low cost.
The AH-4 is a wonderful tuner, and the fact it is mounted at the antenna means that loss due to high vSWR (which mostly takes place in the feed line) is significantly reduced. Not only is it one of the smallest on the market, it also matches a very wide range, and works perfectly with a vertical element of a random wire. I have found performance to be excellent when used with a vertical element, as the take off angle is a lot better for DX work than a low height random wire. The only catch is, unless you put ferrite beads on your feed line and control cable, you may run into issues with RFI in the shack, although this is not an issue with the tuner itself.
All in all, the aforementioned basic setup has brought me a lot of joy; I also used a similar setup in Cambodia and managed 70 DXCC entities in 6 weeks. If the aluminium tube is substituted for a fibreglass telescopic pole with a wire taped to it, the setup makes an excellent portable station, however these poles are best not used in a permanent installation as they will not last as long as an equivalent aluminium tube and are more expensive.
Here are a few photos of the gear (the radio photo I borrowed from Google Images, but mine is the same):
The moral of the story is you don’t need to be rich to enjoy DXing on HF!
This weekend I plan to activate IOTA AS-133. IOTA AS-133 is actually a group of Cambodian Islands, but I will be located on Koh Rong, which is a popular backpacker hot spot where my brother owns a few Hostels.
On Friday the 19th (Cambodian UTC+7 time), I will begin my trip over on the ferry and start setting up the station. I am taking the following equipment:
Icom IC-7200 Transceiver (100 Watts Barefoot)
Icom AH-4 Remote Antenna Tuner (Mounted at the base of my Vertical)
By virtue of the fact my brother has a fishing boat, I have a few decent 100ah batteries available for use. However, Cambodian power often fluctuates between 180-220 Volts, meaning that most of the local chargers (which are linear devices involving little more than a tapped transformer and some diodes), never fully charge a 12v Lead Acid Battery. My little Turnigy charger, although only rated at 4 amps at 12v, easily charges big Lead Acid batteries to full capacity overnight. As such, it is unlikely I will be on the air on Friday, as I will need to charge the batteries up to full capacity in order to get the most out of my radio.
Using a 12M Long Spiderbeam pole, I plan to setup a ‘multiband’ vertical. The Vertical is ‘multiband’ by virtue of the Icom AH-4 Antenna Tuner / Matching Network that will be placed at the feed point. The antenna will roughly be constructed as follows:
The first meter or so of the spiderbeam pole will be buried in the sand, preferably with some additional hardware to use as an anchor point.
Approximately 1 Meter above sand level, the Icom AH-4 tuner will be mounted.
The driven element will be approximately 8 meters long, but adjustments will be made to ensure it tunes up nicely on 15M. 8 Meters is pretty close to a half wave, but the tuner should handle this fine.
The counterpoise will consist of 4 sloping elevated wires, two behind me, and two going out into the ocean. Each will be attached to bamboo supports, and the ocean wires will be kept at water height via flotation devices otherwise known as empty plastic bottles. The counterpoise wires will be roughly 1/4 wavelength on 20M.
Computer modelling and the experience of other DXers suggests this antenna should have a gain between 5dBi and 8dBi, with the highest gain on the higher bands. These figures are quoted for low angle radiation, between 5 and 10 degrees take off from the horizon. I suspect the pattern will be skewed towards the salt water, however this is not shown by my modelling software. It is worth noting however that my modelling experience is limited, and I am using a trial version of EZNEC.
Beginning Saturday Cambodia time, WX Permitting, I will begin operation as soon as I wake up (this is an unknown variable). A little bit of time will be spent setting up the equipment, but as I am planning to use a vertical antenna located right next to / in the salt water, I expect this will take less than 30 minutes.
Depending on band conditions, I will be using a mixture of PSK-31 and SSB Phone. My preference is SSB Phone, so hopefully propagation will be nice.
I plan to operate on the 15M, 17M & 20M Bands, with preference going to the 15M band as it seems to shine in this part of the world.
A lot of Hams hate ‘antenna tuners’, and it’s quite understandable given that there are some common and very bad practices concerning tuner usage.
The June 2015 QST Article ‘Don’t Blow Up Your Balun’ explains this better than I ever could – it explains when and how to use a tuner without causing huge losses. I’ve summarized some of those concepts here, and included some other advantages of using a remote tuner.
Antenna Tuners and ‘Loss’
Back in the days of ladder line, having a tuner in the shack wasn’t such a big problem as the ladder line of the day often had an impedance in the order of 600 ohms, and balanced feed lines are less lossy (have less resistive losses) than coaxial cable when mismatched (being driven into a high SWR). When you combine their high impedance, (which basically means a lower SWR in a mismatch), with their lower losses under mismatch, having a tuner in the shack was not much of an issue.
However when we switched to coax feeds, we should have moved the tuner. Coaxial cable has a relatively low impedance of 50 ohms, which means that when there is a mismatch between the antenna and the feed line, the SWR is generally higher. Coaxial cable also has higher losses (higher resistive losses) under mismatched conditions than ladder line, so when you combine these two things, you can burn up a considerable amount of power just in your coaxial cable. The solution is to move the tuner, or as we should properly call it, ‘matching network’, to the antenna feed point.