Every time I visit Daz I never leave empty handed. Sometimes it’s import radio magazines, antennas, new QSL cards, even radios, but last time it was a little known DMAX40E. Manufactured by Diamond and distributed in Australia by both Andrews Communications and Strictly Ham, the DMAX40E is a wide band preamplifier receiving from 0.5 – 1500MHz. After three nights of experimenting in the shack, the following is what I think about this little unit…….

Let me start by saying that this preamp is for RX only and cannot be used for amplifying TX signals or on the same feedline of a transmitting station, something Daz was terribly disappointed about when the package arrived on his doorstep and the WARNING message was spied. The well packed box came with the preamp itself, as well as a 13.8v power lead, cigarette lighter power lead, four feet (cushions), magic tape and of course instructions.

My initial test was placing it in line with my scanner, a Realistic Pro 2006, connected to a VHF UHF discone antenna at 10m. As the scanner does not have a signal meter, my comparison was with the quality/ readability/clarity/volume of modulation.

Firstly, the Southport Coast Guard tower (VMR 440) is approximately 80 kilometres away from my location and gives weather reports every hour throughout the day. Usually, I have a scratchy copy on their transmissions although it is mostly understandable. With the Diamond DMAX40E Preamplifier in line, I turned the gain control and the sign became a very strong 100% copy. Straight away I was surprised at how well it worked!

Scanning through the frequencies on my RP2006, I started to copy stations that I had never heard before. The Gold Coast Airport, approaching aircraft, and the Coolangatta Fire and Ambulance Service just to name a few, started appearing through my external speakers and this came as quite a surprise. What I found was that the Diamond DMAX40E Preamplifier improved my listening radius by about 40 to 60 kilometres from my location in one of the southern suburbs of Brisbane.

In my opinion, the preamplifier would work well in a car, especially for people living on the outer reaches of the commercial radio stations or those living in rural or outback areas of Australia with limited coverage of commercial radio transmissions. Like with scanning, no doubt, connect one of these units up to your car radio or stereo and suddenly you will have more stations to choose from!

In conclusion, I was very impressed with this little unit and was glad to have loaned it from Daz. I have owned other preamplifiers over the years which claim much but deliver little however this Diamond DMAX40E unit works particularly well. For the money, it is an asset in the shack or car and will bring many more hours of listening variety for scanning, SWL or personal radio use.

According to the product information provided, the unit has the following features:

* 500kHz to 1,500MHz frequency range
* Gain is 20dB max., adjustable down to -20dB
* Low NF (noise figure) of 3.5dB
* Third order intercept point is +15dBm
* DC is fed to DMAX40E via the centre conductor of the coax feedline
* Requires 13.8Vdc (or less) at 80mA max.
* Has two M-type (SO-239) 50 ohm sockets fitted
* Receiver use only - cannot be used with transmitters

If you have any questions about the unit, please feel free to ask or check out http://www.diamond-ant.jp/eng_ama_2.asp.

Dave
43LR155/ 43FR155