david clark dual radio interface

fubb26 · Post by **fubb26** » Fri Jul 07, 2006 5:46 pm

i picked up on ebay a david clark u3816 dual radio interface. i want to interface it into my Low band Maratrac and my UHF Cdm 1550. i have the diagram connections for the radio's.

my question is i am not using this with any intercom system. this is going to be stand alone. i want to use this piece in the back of my chiefs car for IC purpose's.

in the schematic for the module, on the system connector diagram it indicates listen line, V REG line, GND, and talk line.

do i use 12V + on the V reg line or is there a lower voltage that has to be used?

also do any headsets besides a 3000 series headset's work on this interface?

thanks in advance

BDB · Post by **BDB** » Sat Jul 08, 2006 8:17 am

The U3816 is designed to be used with a U3800 master station as it is an active module. I have always used a C3009 for our command cars as a passive interface and a 40107G-01 from the sys9000 heads. The V reg line is 12volts (should be indicated in your U3816 schematic - I'm using a U3811 schematic as a reference) but I haven't personally installed any active modules without a master station in the past. Theoretically it looks like it should work.

fubb26 · Post by **fubb26** » Sat Jul 08, 2006 3:14 pm

yeah that is what i figured. just to make sure im gonna double check with david clark on monday they had the whole week of the 4th off.

BDB · Post by **BDB** » Sat Jul 08, 2006 3:18 pm

They will probably tell you to use the U3800. I'm curious to know what you find out.

fubb26 · Post by **fubb26** » Sat Jul 08, 2006 9:44 pm

so am i but in the past their tech support has been excellent. if i explain the situatian im sure i will get a straight answer.

by the way anyone know how to convert a fire com UH-1 headset to a david clark?

fubb26 · Post by **fubb26** » Mon Jul 10, 2006 3:14 pm

well i spoke to them today and they told me i must use a 3800.
what i dont understand is why? the 3816 is made so no intercom conversations go over the radio's if i send 12volts into the 3816 i should be able to get all of the external functions i need out of it.

oh well
anyone have a working used 3800 they are willing to sell?

BDB · Post by **BDB** » Mon Jul 10, 2006 6:02 pm

The rx audio looks to be routed through the talk line thru the U3800 and back to the U3816. It looks like D/C may be correct. By the time you get a U3800, a couple C3821's , a C38-12, a C3820 , a 40107G-01, a 9227p-1, and a headset you'll have about 1k more than a complete firecom system invested. We use David Clark here exclusively and I haven't ever tried to install an active module without a system. The only interfaces I do without active modules are strictly with PTT adapters (C3009).

fubb26 · Post by **fubb26** » Mon Jul 10, 2006 6:10 pm

ohh i dont doubt them i was just hoping i could do this with out the u3800. i bought the 3816 new in the box for 50 dollars.

BDB · Post by **BDB** » Mon Jul 10, 2006 6:32 pm

You got a great deal - A U3811 PTT station is around 300 bucks and the U3816 is more than that. A U3800 new is 500 bucks. If you can find a source for the module MS connectors you can build your own cables. D/C cables run about $90.00 a piece. There are lots of corners you can cut and make the stuff work - if you can get the connectors. I've had no luck finding a source but I may not be looking hard enough.

fubb26 · Post by **fubb26** » Mon Jul 10, 2006 6:37 pm

yeah i priced it all today 550.75 for the u3800 and the radio cables are 120$ a piece, WOW.

BDB · Post by **BDB** » Tue Jul 11, 2006 5:02 am

Those are full retail prices and can be had for 10 - 20 % less. The modules will last you for a long time. Some of the modules I've used in 3 generations of trucks - that is a testament to the product's longevity.

Post by **wavetar** » Tue Jul 11, 2006 10:31 am

I installed a couple of 3816 boxes as stand-alone units on an oil rig a couple of years ago. They worked just fine. As you surmised, I had to use a +12v power source. As well, I had to short the intercom in & out pins together, effectively making the unit think the audio was leaving to go to a 3800 & then returning to be further processed.

Todd

fubb26 · Post by **fubb26** » Tue Jul 11, 2006 12:23 pm

thanks todd

after looking further and your confirmation i thought i could get it to work that way. cool beans once i get back from bermuda in a few weeks im gonna set it up.

did you use the cables from david clark and cut the connectors off or made the connectors yourself?

also did you have to do that with both of the talk and listen lines or just one of them?

thanks to all again for your help.

BDB · Post by **BDB** » Tue Jul 11, 2006 1:22 pm

Todd,
I hadn't considered running the talk and listen lines together. Sounds like a good idea. I'll try that out here to see how it works.

Post by **wavetar** » Wed Jul 12, 2006 3:42 am

fubb26 wrote:
also did you have to do that with both of the talk and listen lines or just one of them?

thanks to all again for your help.

Yes, shorted both I believe. IIRC, I hard soldered them on the inside...I just used one of the David Clark cables to run the power.

Todd

fubb26 · Post by **fubb26** » Wed Jul 12, 2006 3:32 pm

hey todd do you have a source where i can get the military style connectors?

fubb26 · Post by **fubb26** » Wed Aug 30, 2006 6:03 pm

well after finally getting the time to do this project, i got it done. great setup makes it real easy to hear my radio's. Easy to set up and install. as soon as i can i will get some pics of it up!