In The Ed`s Shack
Contents
1. In The Ed s Shack Kevin Nice fits bhi s latest noise reducing module the NEDSP1061 inside his icom R8500 s regular readers will know I m very pleased with my bhi noise reducing speaker It s in constant use in my shack mainly connected to my flexible Icom R8500 I tend to use the 8500 as the shack workhorse for tuning around and checking my favourite frequencies It is quite useful to be able to use the NES10 speaker with some of my other radios too To this end as I ve mentioned previously I ve arranged a switching system in conjunction with an audio mixer to cater for most of my requirements This solution does have its limitations though One of which is in the case that pick up the R8500 and take it The volume control ended up not being the mod site portable or to an alternative location Not something do lots but it does happen Imagine my delight when I discovered that bhi who must be the foremost supplier of d s p noise reduction systems these days came up with an internal module to fit inside radios The innovating doesn t seem to stop at bhi They seem to have produced a constant stream of excellent noise reduction products over the last year or so Their latest offering the NEDSP1061 noise reduction module is actually intended as a Dealer Fit option for Yaesu s mini FT 817 transceiver After discussion with bhi s technical expert it soon became obvious that could fit2. start the module and the radio After a quick scrutinise discovered that there was a suitable coupling capacitor between the D to A converter used to control level and the set s power amplifier module located this 220nF on the R8500 s main top p c b a surface mount chip type After replacing the front panel I d removed unnecessarily it was on with the soldering SWM December 2005 iron The chip capacitor was soon dispensed with took care to remove it intact just in case want to restore the set to its unmodified state The next job was to install the screened lead used by the NEDSP1061 for input output by soldering the prepared end to the pads intended for the 220nF capacitor This proved to be quite a tricky job as access was pretty tight amongst the other components After much manoeuvring and position changing had successfully connected both inner Now it s gone opinion it s better than the rotary switch alternative especially as the module remembers The coupling capacitor to be removed the last level selected The NEDSP1061 only measure 26 x 37mm and conductors and the screen to the R8500 s p c b Time to find is about 10mm thick at the maximum The four selectable a supply and do a quick test level of operation perform as follows A few minutes later and the board was working All the control of the NEDSP1061 module is performed with presses of the button There are four active l
3. evels of noise Level Reduction Reduction cancellation the module informs the user of current status Noise dB Tone dB by using both the bi colour e d and by injecting a pip 1 11 5 into the audio path 2 13 8 With the noise cancelling module in the off position the 3 19 2i l e d is constantly illuminated red When it is activated the 4 35 65 l e d flashes green and the pip sounds in sync with the flashes a sequence between one and four to indicate the level selected The I e d is I ve yet to finish off the installation as I ve not quite made The removed then extinguished up my mind exactly where to physically locate the module coupling capacitor and but I m very pleased with the performance the label for the control I m tempted to fit one in my HF 150 now switch and indicator le d i The NEDSP1061 is priced at 89 95 inc VAT and is available from Waters amp Stanton Martin Lynch and Sons Radio World or direct from bhi on 0870 240 7258 or via their website www bhi Itd co uk new on line shop The NEDSP1061 is also available as a basic The B S FP pcb module without all the wires and input output lead A z OS 06 7 switches priced at 79 95 in place presumably to conserve power handy if running on batteries The audio tone level is variable which is good as the default level was uncomfortable reduced the level just beyond the minimum setting so as not to be obtrusive The bhi board also featu
4. one of these tiny modules inside my R8500 and so allowing me d s p noise reduction wherever choose to use the set That was the theory the practise turned out to be a little more involved than had anticipated The FT 817 s audio section is pretty straightforward with what can be called a conventional audio section The chaps at 52 bhi have configured the NEDSP1061 module to exploit a common feature of the audio section i e the preamplifier section feeds into the power amplifier via the volume control potentiometer via a 100nF or similar capacitor The method used to tap into the audio path is then to remove this coupling capacitor and use the pre amp output side to feed the d s p module input The output is fed back to where the other end of the coupling Capacitor was fitted or in other words the input to the volume control All pretty straight forward All that was needed in addition to the audio tapping was to find a d c supply between 5 and 15V capable of supplying an additional 45mA mount the d s p module with a double sided sticky pad and drill the R8500 cabinet with two holes one 3 5 the other 4mm for the control button and indicator e d Nothing too demanding and well within the capabilities of a keen hobbyist More Thought My plan was to replicate this arrangement with the install into my 8500 Easy or so thought Without the aid of a circuit diagram or service manual started to stri
5. p down my Icom The upper and lower case shells were first to go the pile of M3 screws grew rapidly Next removed the front panel assembly which contains the display keypad and rotary controls It was the p c b on this module which was the target of my attention and intended modification Once was able to see the layout of the p c b studied the layout with a view to working out where could tap Noise Eliminating DSP Tet 0870 240 7258 into the audio But it turned out not to be as simple as I d imagined After a little visual analysis couldn t find anything like what was hoping for There seemed to be no sign of audio around the volume control Time to switch on the scope and find the DVM After a little probing it was indeed clear that there was not audio around the volume control Instead the radio volume control simply varied a d c level This then presumed was used to control the audio level by more sophisticated means The penny then dropped The R8500 s volume level can be controlled via the RS 232 port so there was The NEDSP1061 ready to fit going to be some digital level control involved Some six hours into investigation called it a day The next morning contacted those very helpful guys at Icom UK s workshop and had a chat A short while later was in possession of a FAX of the audio sections circuit diagram NEDSP 1061 PCB Module Fax 0870 240 7259 Ready to
6. res level controls for both input and output levels found that they were set to optimum positions Once Fitted In use found the NEDSP1061 to be as effective as the other two bhi noise cancelling products I ve used especially like the single button mode selection and reckon that bhi should consider using this method on their other products as in my SWM December 2005 535
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