Here is a link to an enlarged image of Earhart's coupler. Notice the same labeling on the switch, "B," "D," and "R" as shown on the coupler in my previous post.
Gary,
When I made my last post, I:
- knew what a DU-1 was, how it was constructed, and how it worked.
- was familiar with the front panel features of the loop coupler in the Purdue photo.
- had seen the parallels between the front panels of the DU-1 and the coupler in the Purdue photo.
- had supposed that in use, if not in specific implementation, the two couplers were similar, if not identical.
The second question in my last post (
Can anyone produce documentation that a Bendix MN-5 loop coupler was installed in AE’s Electra?) reflects the absence of:
1. proof that the coupler in the Purdue photo was installed in AE’s Electra—either for the first, or second, world flight attempts,
2. proof that the Purdue photo shows a Bendix MN-5 loop coupler, and
3. documentation showing a Bendix MN-5 loop coupler.
The trivial point of the first question in my last post was that the loop antenna for an MN-x direction finder was not necessarily designated an MN-x loop. This is illustrated in your mn-13.pdf attachment where the MN-13 direction finder comprises an MN-13 loop amplifier, an MN-52 azimuth control, and either an MN-20 or MN-24 loop antenna.
The azimuth knob at the loop identifies her's as an MN-5, see attached.
Your three attachments are familiar to me.
If by “azimuth knob” you’re referring to what I called a “hand wheel” in a previous post, then it indicates only that the loop was turned at its base, by hand. The fact that a like loop turning feature was described for an MN-5 in the Aero Digest article is not sufficient to identify the loop coupler in the Purdue photo as an MN-5.
Here’s a question whose answer would be useful:
What are the characters between the words
TYPE and
DIRECTION at the top of the front panel of the coupler in the Purdue photo?
Chuck