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26Apr/120

HP 8935 CDMA Service Monitor EL Display Adapter / Converter

After a lengthy stretch of research on the EL 512x256 Planar display I finally gave up trying to get a datasheet for it.  If you happen to have a datasheet I'd love to get a copy.  Planar didn't have one or so I'm told by there rep.  After a bit of reverse engineering I was able to figure out the output to the display.  I prototyped it on a large FPGA dev board but then wondered if it would be possible to find a usable LCD to fit the frame and to use something a bit more practical to do the conversion.  I have gotten a few responses back from other 8935 owners that they might be interested in a conversion kit of sorts based on what I have done so far.  I also wonder if the E8285A has the same display. If somebody has a E8285A I'd like to know if it has the same display because that might make it worth putting together a kit.  For now I just seem to take a step further and further towards a complete solution each time I power up my 8935 and struggle to tell what input is in the lower part of my screen.

Here is a photo in case you have something similar.  (Note the pilot production tag)

 

25Apr/120

HP 8935 E6380A EL Display Fix

I have a HP 8935 E6380A service monitor that had some pretty severe screen burn.  After looking around for a replacement I wanted to see how hard it would be to adapt a current LCD to the 8935.  Suprisingly it was fairly easy.  I had a 10.5 inch display and after probing around a bit to see what signals/power were on the A1A1 connector (400 i think) I started playing with a FPGA dev board to convert signals to something I could see on the screen.  It works but doesn't fill the entire screen and its not the right size hardware.  Now that I have a PLAN B and I've found a 6.5"ish lcd I can readily buy cheap, I'll troll along with the burnt display till it fails or I can't stand it anymore. I'm hoping there is a lot of interest in this to other 8935 owners and its something I can justify doing in the near future.

Some things I played with while I had the 8935 apart and the 10.5" connected:

- Inversion to have some way of preventing screen burn.

- Adding some color (Changed boarder color, changed color of spectrum analyzer portions of the screen) This isn't something that can be done everywhere. If its simply which pixels get what color it's trivial.

- Added text to the parts of the screen not used going from 512x256 to 640x480.  Could add ADC to show voltages etc as extra info.

-Centered screen and added border.

 

23Apr/120

B & K E200D Issue and the Fix.

I recently discovered my B & K E200D would no longer modulate while working on a Kenwood TS-440AT.  After getting inside the E200D nothing appeared to be unusual and I remember a site I had used before when searching for the switchcraft connector I needed to make a cable for this unit.  http://www.freeinfostuff.com/E200D/E-200D.htm .  After going thru the calibration procedure, everything was in calibration with the exception of the modulation level which once I adjusted the level the modulation meter was back in action.  Easy quick fix and now I know that the unit is calibrated.

13Apr/120

Digital Modem Codec and SDR

I've be looking at several platforms to do DSP work in relation to a SDR and digital modems.  I have a xmos demo board and some AVR32 items laying around which I needed nice DAC/ADC to interface with.  The TLV320AIC23 is a nice inexpensive codec.  I built a small prototype board to use the chip in development products and later I'll turn this into a module that can just be plugged in to various projects.  This board can be used with a small MCU 16-32 bit to do APRS, GSMK (DSTAR), P25 and various other digital demod/mod.  The board breaks of all of the TLV320 channels for both input and output.