Integration. Always the killer...

Well.. The cube survived me throwing it against the wall repeatedly (ok I only pictured this in my mind.. but you get it... didn't do this literally even though I wanted to at several points...)

I first built the 20/30 TXPA (or in original Softrock parlance, PAF-3).. and except for those #$#%ing toroids it was easy.  All parts were there, etc.

If someone from the Softrock crowd is reading this, could you please do us a favor, and where possible switch to commercial RF transformers?  Coilcraft, Wurth (like in the RF-AMP), Mini-Circuits, etc. all make suitable transformers.  Except where they are in a tuned circuit they should work better.  Where they are in a tuned circuit design that part so that a broadband transformer would work instead!  YES WE WILL GLADLY PAY THE $2 EXTRA!

If you insist on forcing 11,000 hand windings of Toroids, could you at least put the six holes on 0.1" spacing so those of us who would first like to solder it on to a header (like a commercial transformer) could?  (Also on the audio jumpers on the Ensemble RXTX spacing at 0.1" instead of wire jumpers would have easily allowed I/Q flips with a short header or cable rather than  desoldering.. geeze...)

Anyway.. as it turned out that was only the start of the fun.  It will be awhile before I worry about TX.  Now it did draw the right amount of current on TX.. so it's probably going to be okay smokey.

But...

The sr63ng/cube/PAF-3/RX-AMP combo didn't receive anything.  So I decided I needed to test the CODEC by the internal tests that are on the AUX serial port menu.  No RS-232.  Well.. it seems that the AUX connector needs to have the cable completely snug when using it or it won't work.  Unless the I/O is screwed down flush, the slot in the case is too small to fish connectors through.  Two hours of messing around I got fed up and took off the subassembly bracket.  Plugged the cable in.. switched RX/TX back to correct.. and voila.. came right up!

Now I'm scared S-less that I'll short something (okay.. I've done that already:  Correction, short something and take something out!) but it's easier barely possible to debug that way.  The cable two posts back is correct and does work for RS-232.

Anyway.. I'm still afraid that the Radio-Shack type 1/8" stereo connector that I used for the AUX might still not fit when the thing is properly boxed up.  I may need to nibble the connector slot open more.  I am not happy about that at all.  Plus the cabling in the cube is like a rats-nest.  I am starting to think that I would have been happier and better off if I went with the original setup, that is the Cube in a case and the Softrock/IF radio external.  But now I am thinking that building it into a bigger box and laying out the boards flat might still have been better.  I suppose that is the price for having the "cute little case".  I would like to demo this radio... and the MBA in me values the Marketing that case provides as much as the Engineer has learned to hate the cube physical design.

I also have to figure out some sort of grommet to keep the ribbon cables from rubbing in the slot.  This isn't a good situation either.

As you can see, the inside of the case is getting quite "busy".  I'm frankly more than a little uncomfortable with it.  Also I am going to have to put a right angle connector on the I2C connector of the DSP card.  This is bad, bad, bad the way it is.  Luckily I dug some up so I can fix this major issue--

The bigger issue is that it sure seems that the SDR-Cube is "deaf".  Compared to a sound card IF, either a lot of CODEC gain needs to be dialed in (which I think isn't good) or the preamp in the RX-AMP card must be used for this thing to act like a radio (I *think* as mine isn't working).  I'm wondering if there shouldn't have been an additional op-amp stage on the DSP card prior to the CODEC.  That may have killed dynamic range.. but I expect "hiss" out of my radios when I turn them on unsquelched!

I think my RX-AMP might not be working.  After several hours of playing with the cube, measuring voltages, resistors, caps, on the SR63ng... verifying with the frequency counter the si570 is working and tuning (it does), verifying the 74AC74 /4 divider works (it does) and several different things, I took the RX-AMP off and hooked a long piece of wire to one of the connectors on the BPF plugin on the sr63ng.  The signal generator nearby instantly became audible to the cube.  But it's still significantly more deaf than the Kenwood R-2000 I also had monitoring the signal farther away with a shorter wire antenna.  I have to figure something out.

If it's the RF-AMP board, and the SDR-Cube needs the pre-amplification I can understand what is going on.  It's giving me fits now though.  Maybe I do have something that's affecting the CODEC input.. but hooked to the PC, the audio levels seem reasonable, so I don't know.

One thing that is really neat-o when testing is to make a cable to hook your computer up the line input of the Cube and go to the softrock40 groups file downloads and look for the DL6IAK Tone Generators and I/Q generator download and get the nifty I/Q generator.  I knew the cube was working when I tried than and then assumed it had to be something wrong with the sr63ng.  I now think the sr63ng (at least LO and receive) is perfectly fine.  I think the RF-AMP isn't working.  That's next in the debug.

And... yes.. one or both of those frequencies can be NEGATIVE and when you do that they end up on the LSB side of the display of the SDR-Cube.  ;O)  Cool toy.

I'll get there eventually.. probably soon actually.. the only thing I can say it's extremely difficult to do debugging with the cube in the way.  But I'm afraid of shorting everything and blowing it up to kingdom come if I started to disassemble things.

I am debating building another RX-AMP up (since I have two more) or building a classic filter on perfboard as from the original Softrock design.  But another option would be to build a broadband transformer on a board for testing.  I need to do something to continue.