[DSP-10] DSP-10 with DSPx problems and solutions

[ve3ytz at sympatico.ca]

Thank you Hermann for your update. You seem to be taking the DSP-10 project to a new level. You mention:

"I made a lot of changes  (including the known changes by the Assembly Manual) to all three DSP-10  projects and noted them down for whom it may concern."

May I ask were your comments are found? I am certainly interested in  seeing your changes.

Thank you again Hermann and to Bob for his excellent project.

73

Greg Danylchenko/VE3YTZ  
> 
> From: DC9UPGermany at aol.com
> Date: 2005/01/22 Sat AM 05:38:16 EST> To: dsp-10 at mailman.qth.net
> Subject: [DSP-10] DSP-10 with DSPx problems and solutions
> 
>  
> Hello  DSP-10 friends...I just have finished the third DSP-10. Two of them 
> were with  the original EZ-Lit-Kit and worked out very fine. I made a lot of 
> changes  (including the known changes by the Assembly Manual) to all three DSP-10 
>  projects and noted them down for whom it may concern.  
> The  third one now includes the new DSPx processor and it?s also a fine 
> instrument on  receive. I can not detect any birdies over the range 144 to 146 MHz 
> (this  range is used in Europe!) and maybe this has to do with  the shielding 
> technique I used. 
> First: 
> The  top-cover of the DSPx box has extra lids with 14 screws around to hold 
> them  down to the box. The box should be "watertight". 
> Second: 
> I  used very thin white shielded Aircraft-wires for most of the back-plane  
> connections, especially the once which distribute signals. Besides  this, I 
> used fine semirigid cable for the LO oscillator signals which can be  soldered 
> directly with the outside to backplane. 
> Third: 
> The  cable routing inside the box and outside the box is done in a very  
> different way compared to the original project. 
> I  also build the DSP10 PCB not the way the assembly manual and the 
> associated  parts layout show. The building process was done by "Group-building" and  
> testing each group of circuits after soldering. By this way problems can be  
> traced down easy and when ready with all groups the DSP-10 works right  away. 
> The  main changes I made are in the LO parts and their amplifiers. Their  
> inter-stage gain and levels must be corrected not to overdrive the following  
> amplifiers (MSAs) and deliver the right undistorted level to the  mixers. 
> All  changes are documented down here. 
> ------------------------------------------------------------------------------
> --------------------------------------  
> The  only program working after the download from the PC to the DSPx is the 
> one from  Bob on his website. (_http://www.proaxis.com/~boblark/uhf3x_25.zip_ 
> (http://www.proaxis.com/~boblark/uhf3x_25.zip) ) 
> No  other version will work with the DSPx !! 
> Download  is done by the EZFast Loader with the command line: 
> Ezfast L 1 uhf3x.exe  G 
> The  L stands for loading with 9600 b/s; no fast loading with an "M" is  
> possible.!! 
> The  1 stands for the COM port, 1 in my case. 
> So  far so good. The DSPx seems to work as good as the old EZ-Kit. Good work  
> done by Lyle. 
> Now  I run into the first (maybe small) problem. 
> On  transmit the Codec in the DSPx part can easily overdriven by the 
> Microphone  input in all modes, FM, USB, LSB etc. 
> SSB  sounds very bad and it does FM-ing and after scoping around and looking 
> to the  output signal with an SA, I could see that the carrier is wandering 
> when  overdriven and has some FM on it. 
> Bob  came around this problem in the original EZ-Kit and installed a  
> "Clipper". 
> But  this clipper does not work properly with the DSPx.!!! 
> I  think it must be reworked to match the new CODEC. 
> One  more remarkable problem occurred to me. 
> Changing  the MIC gain from 61 to 60 completely shuts off the clipper  !!?? 
> After  shutting down the program and the DSP-10 and restart again it will 
> work  again....curios..??? 
> Did  somebody else experience this too?? 
> Best  73 and happy work with this outstanding TRX DSP-10...I am lucky with  
> it. 
> Hermann,  DC9UP     
> E-Mail:    _DC9UPgermany at aol.com_ (mailto:DC9UPgermany at aol.com)  
> (mailto:DC9UPgermany at aol.com) 
>  
> _______________________________________________
> DSP-10 mailing list
> DSP-10 at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/dsp-10
>