Why won't my mcx1000 decode DES? The boards work on others?

saberjerk · Post by **saberjerk** » Tue Dec 14, 2004 12:14 pm

Hi
I have a mcx1000 that is giving me fits. It will encode and transmit DES correctly but won't decode it. All the radios are 440-470mhz 56 mode remote mount units. I swaped the extender and carrier boards with hybrid around to several other radios and they all work fine except this one. The key is the same and it loads fine.
I even went as far as to change out the radios main board, analog board, and command board no change.
The radio does work fine in clear mode by the way.
What am I missing here????
Is there something on the front panel interface board that could be causing this?
At this point I'm clueless. I've replaced everything except the VCO, synthesizer, and front interface board.
Any help would be greatly appreciated.
Thanks
Dennis

1motoman · Post by **1motoman** » Tue Dec 14, 2004 9:26 pm

Do you have the HUB inabled ?

k4wtf · Post by **k4wtf** » Wed Dec 15, 2004 12:22 am

Perhaps its an alignment issue? I've seen this on Sabers but, I'm not familiar with the MCX1000's so it might not act the same.

John

saberjerk · Post by **saberjerk** » Wed Dec 15, 2004 6:22 am

Hi
Thanks guys for some of the ideas.

The radio doesn't require hangup to operate.
I just dumped the same codepluge into the radio that was from
the other radios that work. The radio functions normaly just no des decode. Transmit on DES works fine. I verified with a working radio.

Would it have the same alignment problem with 2 main boards? Remember I changed out the main board. The only ajustments on the
board are squelch, vco mod, and power output. There is the frontend
tunning and I did that. I don't thing there are any softpots like saber.
Thanks
Dennis

RADIOMAN2002 · Post by **RADIOMAN2002** » Wed Dec 15, 2004 12:06 pm

When decoding DES the radio HAS to be exactly tuned on channel,within a few cycles per second and the transmitting radio HAS to have a tx deviation of between 3.75 and 4.25kc. No ands ifs or buts. Also try changing the hybrid, never seen one go but anything is possible.
The only other possibility is the crystal filters in the IF section, a bad one may not have the bandwith to pass the DES signal which can be around 6kc. If you get into real troubleshooting, put a scope on a good radio discriminator and get the cats eye, then check the bad one for the same

saberjerk · Post by **saberjerk** » Wed Dec 15, 2004 12:46 pm

Wow!!!!!!!!
Radioman2k2 you were right on the money.
The radio was off by about 2kc. This is the first mcx1000 I've
seen be off by that much. I'm almost embarassed to admit I didn't
even check that. Well another lesson learned. I'll have to check
the other radios. Works beautifully now!!!

Thanks all
Dennis