Batboard

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

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.

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.

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

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?

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?

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).

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.

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.

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

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.

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

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.

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.

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

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

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!