Thanks for educating me on the DAV internal loop setup Breck. I thought it used an external loop. Never owned one. 

I wonder if you used MN 62 or ARN 7 ADFs (nearly identical) during your transport flying days. I tweaked an R5A ARN 7 to receive and DF on the old 2-3 MHz marine band and installed it on my dads boat. It was a great ADF. Worked better on marine and beacon bands than any purpose built marine ADFs including KODEN, Taiyo, Raytheon, Bendix and others. 

73,
Mark
AF6IM 



On Sat, Nov 25, 2023 at 4:15 PM B. Smith <smithab11@comcast.net> wrote:
Hi Mark
In this case the DAV is used for receiving and has a distorted pattern. The loop antenna BTW is wound around  a form inside the wooden box. I've checked the inductance/capacitance etc but I suspect the loops location inside the set  is poor. My guess is the DF  pattern was skewed and probably not very usable even when it was manufactured. BTW it is easier to determine the "Null" on a weak signal if you are just using listening to earphone audio and not using a  meter. Been there and done that while flying transports.

BTW The BC-611 DF antenna works great but you have to fabricate a outboard coupler for the antenna.
http://k4che.com/BC611DF/BC611DFpg1.htm



On 11/25/2023 4:57 PM, boeing377@gmail.com wrote:
I have many years of experience using RDFs and ADFs crewing and later skippering commercial fishing boats. I’ve shot bearings on USCG and FAA beacons, AM BCB stations, other boats on 2-3 MHz AM and weak net buoy beacons operating just near the bottom edge of the 160M ham band. It’s VERY hard to get useable loop antenna directional nulls on weak signals. DAV and BC 611 are not great DF targets. Signal is too weak unless you are very close. Others may hold different opinions but this is my experience. 

73
Mark
AF6IM 



On Sat, Nov 25, 2023 at 12:06 PM B. Smith <smithab11@comcast.net> wrote:
I've worked with the DAV  quite a bit.  Also worked with Robert  Downs on a revised schematic.  My only problem with the DAV is using it for DF - I can not get a decent figure 8 pattern. Building a battery box  is a week end project.  
k4che


On 11/25/2023 11:31 AM, David Stinson wrote:
Is there anyone left who cares about and
actually works with the WWII MAB / DAV,
arguably the Marine Corps version of the BC-611?

73 Dave S.


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