I guess time to post here rather than just on the Yahoo milpack group.  This way it’s easier to find all the updates in one spot and in order.

The KY-67 is a very rugged VHF backpack transceiver covering the usual 30-88 MHz and made in the eighties.  My impression was that it was made for an amphibious vehicle which experienced program delays so by the time the program went into production the radio’s technology and features were dated and not many were produced.

The unique part for the time was that the radio had integral digital encryption.  Of course what this means is that for all radios which were surplussed the encryption boards had to be removed so every one of these anyone outside the military has seen is missing all those cards.  While I commend the surplus disposition people for not just grinding the radio up to scrap, the removal of those boards renders the radio inoperational.  Completely dead.  Some have tried, but no word of anyone ever succeeding.  Of course, the funny part is that I will likely only use this radio several times a year, and probably all on 51.0 MHz.  But it looks really cool and rugged, like you could run over it with a truck.  So I’m going to try and get it to run.

A kind soul offered me one with mounting base, unused, for the cost of shipping.  Let the games begin, it against me.

Next post I’ll add some photos.

Here’s a summary of my progress to date:

Two battery connectors for two 2590 type batteries.  One runs the encryption boards, the other the radio itself.

The CPU board operates the front panel display.  I was worried it might be controlled by the missing cards.  CPU is a NSC800, an extended temperature range Z80,  Firmware was on a socketed (yay!) 27C256.  Hmm, only 64k instructions at most, doable..

Read it out, ran some Z80 disassembler I found on the web, got this:

https://github.com/kb2vtl/KY-67

Look at the .asm file, that’s the one I’m annotating as I go.

Oh, one more thing in the hardware, you have to remove the little gold case FET on the CPU card near pin 72 of the connector.  This will allow the processor to run when the missing cards are out.

Once running, the displays blinks 6 6 6 five times and shuts off.  After a lot of tracing, I’ve identified the display writing routine, error reporting, and the entire extensive POST routine.

Also discovered some funky backup battery scheme which I don’t understand at all quite yet.

Found the routing where the 6 6 6 is displayed and bypassed the call to that subroutine.  Now the radio gives a 1 09 indication, or sometimes a 1 07 one.  I bet this means some other CMOS signal is floating coming from the missing cards.

Probably going to wander around the software and try and figure out more stuff.

I wrapped up the radio for the time being.  It’s not internally 100% the way I’d like it but I need some time to work with it before I consider the firmware truly final.

A few notes:
1)  I traced out the radio LCD backlight wiring.  There are four LEDs in series with the high side connected to 10 volts and the low going through a transistor and resistor.  I had previously found that 1k in series was nice for general LCD lighting and full 5 volts for high brightness.  I tied the new display positive backlight to +5 and the negative to the collector of that transistor.  I put a 1k resistor across the transistor and shorted out the 220 ohm resistor.  Here is what that mod looks like:

Yes, that’s a really tiny resistor I used!

2) The flex cable to the front processor board is not very robust.  Earlier I lost the ability to turn the radio on and found that the pin 40 to pin 40 connection was lost in the cable.  Now the 3 bars started going intermittent and I traced it to the loss of connection in pin 39.  Here is my fix:

About the only choice seeing as the part is unobtainium.  But it works great.

3)  The new LCD display annoyingly requires a negative ~1.66 volts for bias to work.  More annoyingly there is no negative supply I could find in the radio so I had to make a small 555 based charge pump.  I would prefer to use a tiny SO-8 part to do this, one meant for the purpose, but that will have to wait until I have enough to order from Digikey to have a reasonable size order.  In the meanwhile I stuffed it here:

Left of that are three precision resistors which make the voltage divider for the voltage display I added.  When I go back in I will tack glue three SM resistors on the other side to eliminate this eyesore.  Here is where the sense wire ends up connecting to the CPU board pin 39:

I didn’t take a photo of it but have the 6 wires from the Arduino going to a tiny connector which is between the boards.  I can connect my code development computer to it if I want to update the code without having to disassemble the whole thing.

I took a video but it is too large for this site so I placed it on my site at the following address:

http://petergottlieb.com/images/syncal.mov

Note that when the display goes to the bright setting the iPhone camera can’t handle it and washes out.  It’s pretty bright, gotta love these new high efficiency LEDs!

Now I play in the field!