[DSP-10] Resolved - the DSP-10 problem!

Sat Apr 27 14:49:41 EDT 2013

Don, I just read through your whole ordeal (having been overwhelmed at work for the last month).  It reminds me of bringing my DSP-10 up for the first time in Spring of 2005.  The whole excruciating story was blogged live at

http://cbduncan.duncanheights.com/HamRadio/Dsp10/PhaseOne/PhaseOne.html

Following some all-nighters in March to get the box all working, there were some more all-nighters in June when I was getting the Brickette going. 

Later I built a Communications Concepts Inc., 875A 2-meter linear to get the whole stack up in the 60 W. range (48 dBm...) and that worked fine for quite a while until I built a W1GHZ 1296RSU converter and started using the DSP-10 nearly exclusively on 23 cm.

The reason I mention all this is to say that my DSP-10, that I got working in March 2005, has been powered up nearly continuously since then, monitoring various beacon, calling, and other frequencies of interest 24/7.  I have the screen scrolling very slowly (SpecAve 8 1200 / SpecAnl Non 4800) so that the waterfall is about ten hours deep and I come in and save a screen shot several times a day.  In all that time I've not had any problems with the DSP-10 itself except once when the speaker jack wobbled loose causing a near panic!  (Or the ancient DOS / Windows 3 PC that it's hooked to for that matter.)

Knock on wood, I suppose.

Congratulations on a successful resolution and good luck with your plans.

Courtney, n5bf/6

On Apr 15, 2013, at 8:36 PM, Don AE5K wrote:

> I am happy to report my DSP-10 is now putting out approximately 13 mw  ( +11 dbM ) and I believe we found the cause of the power jump intermittent.
> 
> Today, as previously planned, I brought my DSP-10 and instrumentation to Gary K5QNM's residence (50 mile drive) and we both worked on it trying to first find the source of the intermittent and secondly to see what we could do to increase the power output from about +3.6 dBm. It pays to troubleshoot with an extra pair of eyes present along with a 2-way discussion in real time.
> 
> While looking for poor solder joints or other problems around the transmit chain (U4-U5-Q2), we had the DSP-10 turned on but in receive mode at one point, and Gary was moving the multicolored short ribbon cable (at least on my TAPR kit) to get a better view when we heard a lot of scratchy static on the speaker.  Ah-ha!  Removed power and I tried to remove J5 at the end of this cable going to P5 on the main board.  In so doing, the wire ends came right out of the connector!  J5/P5 contains the following signals from the DSP box: ADC-L, GND, ADC-R, DAC-L, GND, DAC-R.
> 
> Further investigation showed that my "crimp" job of those 6 conductors left an awful lot to be desired.  Instead of re-crimping, Gary soldered the connector parts and I re-installed the connector and the DSP box.
> 
> That did it!  The power was actually the same as before the discovery, but we think that was the cause of the power jumping lower at times.  I might add that before this wire pull-out happened, the sidetone on transmit seemed much weaker today than in the past.  After repair, there was NO SIDETONE!
> 
> We went ahead and with makeshift coil core tuning tool, managed to go thru L8 thru L12 peaking for maximum transmit power.  (This had been done once the other day)  The end result: +11.1 dBm (13.1 mw) but still no sidetone at all.  I had only the mono unpowered speaker connected thru a mono jack. [Note: later at home, at cold start power measured +11,2 dBm 13.8 mw.)
> 
> Upon returning home, I re-setup the DSP-10 and added a pair of powered stereo speakers with the stereo 3.5mm jack.  Voila!  Nice sidetone in the right speaker.
> 
> I've not checked out everything, but I have confidence we found the real problem. The only mystery in my mind remaining is why previously we heard the sidetone on the mono connected speaker and after the fix only could hear it on a stereo connected speaker.  I know the sidetone is only produced on one channel, but what wire failure would cause the mono to work before the fix?
> 
> I would like to thank Mike KD5TS who once again came to my rescue (we had some previous correspondence a year or so ago too) and for sticking with me on this.  And to all the rest of you who contributed suggestions.  And to Gary K5QNM who assisted me today.  It is all sincerely appreciated.
> 
> Now, onward to getting an old NTMS (North Texas Microwave Society) 1296 transverter back to working condition plus power amplifier that will allow me to eventually put out about 15 watts on that band.  I'm ashamed to admit it, but Gary and I have been at this 1296 project for over FIVE years now and I expect very soon we'll easily cover our 32 mile as the eagle flies path.  A rovering I shall go!
> 
> 73,
> Don AE5K
> EM36pc Marion County, northern Arkansas
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