If you’re looking to perk up the quality of your RX and don’t have the cash to throw at a new transceiver with the marvel of Digital Signal Processing (DSP), then this next wonder gadget may be for you. Clearly, the major benefit of using any DSP unit is that you don’t have to put up with the harsh noise that can often dominate 27 MHz and render 11m DXing useless. Enter the NEIM1031 which incorporates the latest DSP technology to remove unwanted background noise and interference from speech, and you’re entering into a DX-citing new world of RX!

A while ago on 11m DX Activities OZ, I reviewed the NES10-2 Noise Eliminating Speaker and also the terrific Noise Cancelling Headphones by Heil, but this next DSP product, for my part, ranks on the same stage. The NEIM1031 is what’s called an ‘In-Line module’ and from all reports was developed by manufacturer bhi as a response to DXer feedback about the NES 10-2. Evidently, some radio shack operatives indicated that they would like an inline unit without a speaker, not as a surrogate, but as an alternative profile.

Besides the improvement to RX and being able to pull in weak signals, another sizeable attraction for me was that it can be fitted to an existing speaker. This allows the fashion conscious DXer to stick with some of the more stylish speaker systems on the market rather than trade them in for a smaller, less sophisticated looking type with DSP. The NEIM1301 module straight from the External Speaker socket, for example, worked effectively with my preferred Kenwood SP-23, which I would be hesitant to exchange on a full time basis as it compliments my TS2000 so well.

At just 170 x 85 x 34 mm, the NEIM1031 was very easy to set up with my existing speaker and begin operation. In fact, once power and audio leads were connected, including my Heil ‘Quiet’ headphones into the NEIM1031’s headphone socket, it was all systems go to start testing my new setup on some weak signals from other 43 Division states and territories.

As you would hope, noise cancellation can be switched ON and OFF on the unit which provides some flexibility in use. The input audio level can also be adjusted and a green LED indicates the input audio level is okay while a red LED illuminates if the level is too high. With an eye on the LED’s, you can also adjust the audio input control. Additionally, there is a control for audio output as well to set the volume for up to 2.5 Watts RMS into 8 Ohms. That is stacks for most users by the way, but external amplification can be added post-bhi if you are greedy, lol.

The extent of noise cancellation by the NEIM1031 is inhibited by a small rotary BCD switch. Here, minimum noise cancellation is at position ‘0’ while ‘7’ is the maximum. As you would expect, the level of noise cancellation is adjustable too while the unit is in use, nevertheless this is still a big attraction. Essentially, how much noise cancellation you use is dependent of the operator, type and level of signal and amount of noise present on the band.

When noise cancellation is set at ‘7’ almost all noise is removed although the audio takes on a rather robotic sound when set at this level. Normally you would use such high processing for the most severely noise effected signals only or to draw out that rare DXpedition station which hovers at the back of the box amidst a wall of Indonesian fishing boat TX.

It most cases I use a setting of 3-5, however this is entirely subjective and it is my thinking that every user will choose a level that suits them and their listening needs best. Needless to say that some would favour no noise and accept some audio degradation, while others will have best audio and accept some noise.

This small rectangular unit is powered from an external DC plug pack, which is not supplied, with the acceptable input voltage range from 12-24 volts. The audio in and out is connected either via a pair of RCA or 3.5mm jacks at one end of the case. On the NES10-2 which I dealt with a few months ago, a dual in-line switch was used to adjust the degree of noise elimination whereas a rotatory switch performs the same adjustment on the NEIM1031. It’s a trivial line of reasoning but a high profile knob would be better in my estimation (Calm down Miss Deb!).

One concern I had with the module was with the size of the rotary switch. The numbers are tiny and require a microscope to see (almost!), although there is no real need to see them when all you care about it is the quality of the audio. The NEIM1031 does come with optional extras which include a horizontal label and a mounting stand which firmly holds the unit during operation and I would recommend these also.

If you are interested in adding DSP to your communications then the distributor for bhi in 43 Division is Andrews Communications in Sydney. Occasionally, a product such as the NEIM1031, with its greatly improved signal to noise ratio, pops up on VK Ham but due to the quality of the product and their effect on shack operations don’t hold your breath on anyone offloading one until something better hits the market.

73

Darren
43SD054/ 43FR010
Admin Team
11m DX Activities Oz