Davtron 701 Connection to a Bendix T12C

[Ned Gravel]

Now before anyone gives me a hard time for:

a.  using and ADF, and

b.  using one as old as a T12C

let me say that this puppy is VERY reliable and works over quite a distance.  Besides, with y'all about to lose your satellites to 4G telephony, I still want to wear both belt and braces. 

Now to the question stumping me. 

What are the connections between the Davtron 701B (basically a frequency counter that shows a digital display of the frequency being tuned by the T12C) and the ADF itself?

The pinout for the T12C is:

Pin 1 Sense antenna
Pin 2 Loop shield
Pin 3 Loop Input R1 (Tin)
Pin 4 Loop Input R2 (Copper)
Pin 5 Optional Audio Amp A+
Pin 6 Dial Lamps
Pin 7 Tuning Meter (ext)
Pin 8 47Hz switching Phase 2
Pin 9 Ground
Pin 10 Servo DC Output
Pin 11 Spare
Pin 12 47Hz switching Phase 1
Pin 13 Servo DC Output
Pin 14 Headset (500 ohm)
Pin 15 DC In +
Pin 16 ADF Servo Signal Output

 

I get that one of them is probably connected to the T12C's pin 7 for the external tuning meter, but I really need to know if anyone has hooked up one of these, or even better, has a copy of the pinout for it - the Davtron 701B that is....

 

 

[Piloto]

I have never deal with the Davtron 701B but with the T12C. I used to have one 30 years ago and was my only form of navigation over long legs of water. Since you can not rely on the frequency dial for accuracy I always identified the station by its Morse code. Looking at the T12C pin out, none of those will provide frequency data. In order for the Davtron to read the frequency it will need to be connected to the ADF receiver local oscillator thru one of the spare pins on the connector. The local oscillator LO frequency is either 455KHz or 262KHz above the receving tuned frequency. Thus the Davtron 701B has to subtract this number to show the proper tuned frequency. One of the annoying problems with the T!2C is that in the vicinity of thunderstorms the needle will point toward the storm instead of the station. The later ADFs receiver like the KR-87 use coherent detection so they are not subject to thunderstorm interference. Also the digital frequency readout makes it much easier to tune. You can also replace the T12C with the T12D which has digital tuning.

José 

[Ned Gravel]

I just wanted to let everyone know that I found the answers I needed.  I received description and pictures from someone on one of the other Mooney lists.  He is obviously skilled in the use of a PACE kit and I now know exactly how to connect each of the Davtron leads to make it work properly.

Great and supportive community....

Thank you.

 

[b737 thu]

I know this is a Really old Post, but if you are still around and could share how the 3 wires for the 701b hook up, I would love to know.  Forgot I had a Davtron in my hanger. Setting up a static display of old worn out radios from planes I've had. Would love to have this working as I tune the old ADF.

Thanks

Britt Thurman b737thurman@yahoo.com

Edited August 2, 2018 by b737 thu
Wanted to add notify of reply. Can't find it now.

[carusoam]

Welcome aboard, Britt.

I’ll invite @Ned Gravel out this way to see if he can shed some light on the subject...

Its been a few years.  The good news... Ned’s plane is getting newer every year....  

Best regards,

-a-

[b737 thu]

Thank you -a-!

[Ned Gravel]

7 hours ago, carusoam said:

Welcome aboard, Britt.

I’ll invite @Ned Gravel out this way to see if he can shed some light on the subject...

Its been a few years.  The good news... Ned’s plane is getting newer every year....  

Best regards,

-a-

I had it all worked out and about two weeks before I was ready to wire them together, I got an offer on a KR 87 and had Brant Aero replace my T12C with it. No need for the Davtron.  Removed the long wire antenna and added 0.05 knots to my IAS.  

[b737 thu]

It was a nice try. I think this was my last hope.  Now, I'll just hook the hot and ground up to see if it even lights up.  

Thanks for the reply guys.  I have a Ximango Motorglider, so you may not see me again here, but thanks for the effort!

 

Britt

[carusoam]

We’re gonna need a pic of the Ximango, Britt... 

Best regards,

-a-

[b737 thu]

Here you go.  Makes the $100.00 hamburger into a $10.00 hamburger

[b737 thu]

Takeoff power 4.5 gph. Slow cruise 2.5 gph.  Thermals=0 gph!  The retirement plane of my dreams!

Britt