RDF Loop Control

[Mark Pearce]

A WWII vintage Bendix D. Finder is about to be sold off on E-Bay-  It has some features in common with the 1937 model.  Good upclose views can be seen-

http://www.ebay.com/itm/WW-2-AIRCRAFT-RADIO-DIRECTION-FINDER-LOOP-MODEL-DU-1-COMPLETE-TUBES-/140799339726?pt=LH_DefaultDomain_0&hash=item20c84b6cce

AN EXCELLENT ORIGINAL WW 2 AIRCRAFT RADIO DIRECTION FINDER LOOP MODEL DU-1 COMPLETE WITH TUBES STAMPED ON BRASS TAGS " COUPLER UNIT TYPE CRR-50061 MANUFACTURED FOR NAVY DEPARTMENT BUREAU OF SHIPS BY BENDIX RADIO CORP.BALTIMORE,MD. " AND " RADIO DIRECTION FINDING EQUIP. MODEL DU-1 " ALL SWITCHES AND CONTROL MOVE FREELY ,FREE

[Gary LaPook]

A WWII vintage Bendix D. Finder is about to be sold off on E-Bay-  It has some features in common with the 1937 model.  Good upclose views can be seen-

http://www.ebay.com/itm/WW-2-AIRCRAFT-RADIO-DIRECTION-FINDER-LOOP-MODEL-DU-1-COMPLETE-TUBES-/140799339726?pt=LH_DefaultDomain_0&hash=item20c84b6cce

AN EXCELLENT ORIGINAL WW 2 AIRCRAFT RADIO DIRECTION FINDER LOOP MODEL DU-1 COMPLETE WITH TUBES STAMPED ON BRASS TAGS " COUPLER UNIT TYPE CRR-50061 MANUFACTURED FOR NAVY DEPARTMENT BUREAU OF SHIPS BY BENDIX RADIO CORP.BALTIMORE,MD. " AND " RADIO DIRECTION FINDING EQUIP. MODEL DU-1 " ALL SWITCHES AND CONTROL MOVE FREELY ,FREE

Here is a photo of the front of the coupler of EBAY which also has the directions for use and is the same method used with Earhart's RDF.

gl

[Chuck Varney]

Here is a photo of the front of the coupler of EBAY which also has the directions for use and is the same method used with Earhart's RDF.

Gary,

Your statement suggests that you know what Earhart's direction finder was. What was it?

Chuck

[Jeff Victor Hayden]

Chuck
from early March 1937 onward, the aircraft was equipped with a Bendix MN-5 loop antenna

http://tighar.org/Projects/Earhart/Archives/Research/Bulletins/53_MiamiPhoto/53_MiamiPhoto.htm

[Chuck Varney]

from early March 1937 onward, the aircraft was equipped with a Bendix MN-5 loop antenna

http://tighar.org/Projects/Earhart/Archives/Research/Bulletins/53_MiamiPhoto/53_MiamiPhoto.htm

Jeff,

Gary structured his reply as if he not only knew the specific direction finder installed in Earhart's Electra, but that he also had operational documentation for it. I wanted to hear about that.

Yes, your link includes the sentence "Photos show that from early March 1937 onward, the aircraft was equipped with a Bendix MN-5 loop antenna.", and I ask:

Can anyone produce documentation that a Bendix MN-5 loop antenna designation even existed?

Can anyone produce documentation that a Bendix MN-5 loop coupler was installed in AE's Electra?

Chuck

[Gary LaPook]

from early March 1937 onward, the aircraft was equipped with a Bendix MN-5 loop antenna

http://tighar.org/Projects/Earhart/Archives/Research/Bulletins/53_MiamiPhoto/53_MiamiPhoto.htm

Jeff,

Gary structured his reply as if he not only knew the specific direction finder installed in Earhart's Electra, but that he also had operational documentation for it. I wanted to hear about that.

Yes, your link includes the sentence "Photos show that from early March 1937 onward, the aircraft was equipped with a Bendix MN-5 loop antenna.", and I ask:

Can anyone produce documentation that a Bendix MN-5 loop antenna designation even existed?

Can anyone produce documentation that a Bendix MN-5 loop coupler was installed in AE's Electra?

Chuck

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. The azimuth knob at the loop identifies her's as an MN-5, see attached.

gl

[Chuck Varney]

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

[Gary LaPook]

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

Yep, frustrating ain't it. There it is, right in front of us, and we can't read it.

gl

[C.W. Herndon]

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

Yep, frustrating ain't it. There it is, right in front of us, and we can't read it.

gl

Gary, Chuck, we have primarily been looking at the Purdue e-archive photo of the loop coupler, see photo #1 below, while trying to determine what the labels say. Earlier in Chuck Varney Post #38, Chuck posted a composite picture with a top half and a bottom half. The top half was a picture provided by Richie Conroy but the bottom half was a picture provided by Chuck. This bottom picture provides a different view of the loop coupler in which the entire face of the unit is visable, see photo #2 below. I can't read the lettering on the copy provided but was wondering if it could be read in the original picture? Sure would be nice if it can.

[Chuck Varney]

This bottom picture provides a different view of the loop coupler in which the entire face of the unit is visable, see photo #2 below. I can't read the lettering on the copy provided but was wondering if it could be read in the original picture?

Woody,

You'd have to find the original photograph for an answer to your question. The scan that you see was made at 200 ppi from a book photo (~ 2-1/2" x 3" and none too great in quality). The Purdue image was scanned at 600 ppi from an 8" x 10" print. If you want a research project, you might contact Purdue to see whether their original reveals anything not legible in their scan.

Here's what I see on the front panel in the Purdue photograph:

1.  It is marked

   TYPE XXX DIRECTION [FINDER]
   BENDIX RADIO CORP[ORATION]
   WASHINGTON D.[C.]   

    where XXX = unreadable and [ ] = presumed.

2.  It has a 5-position band select switch marked BAND and 1, 2, 3, 4, 5.

3.  It has a 3-position function selector switch marked B, U, R or B, D, R (B, D, R was common in later units like the Bendix DU-1 and DW-1).

4.  It has a control marked LOOP TUNING.

5.  It has an antenna binding post marked A.

6.  It has an ON / OFF toggle switch.

7.  It has three other features which may be, left-to-right near the top of the panel: a circular access cover, a dial light for the loop tuning dial, and a knurled cap.

Chuck

[C.W. Herndon]

Thanks Chuck. Your eyes are much better than mine.

I was afraid that, or something similar, was the answer. I may try to work on it a little.

Hang in there.

[Gary Vance]

Has anyone seen this picture from the Smithsonian?  I looked and couldn't find it or a link anywhere on this site. It shows Amelia holding the very thing that could have saved her life and made the trip a success! I apologize in advance if it's a redundant post....

http://timeandnavigation.si.edu/multimedia-asset/amelia-earhart-holding-bendix-radio-direction-finder-loop-antenna

[Jeff Lange]

Great find Gary! What an ironic picture considering what happened shortly afterwards.

[Martin X. Moleski, SJ]

Has anyone seen this picture from the Smithsonian? 

http://timeandnavigation.si.edu/multimedia-asset/amelia-earhart-holding-bendix-radio-direction-finder-loop-antenna

Yes, it is an iconic photo.


We have one like it in the "Direction finding" article.





Probably the same photo shoot.

[Bruce Thomas]

... and in this Forum post that Randy Conrad made 4 years ago, we see the complete picture of Amelia holding the loop antenna. Amelia's shoes that she was wearing were an object of interest at that time.