TIGHAR
Amelia Earhart Search Forum => Radio Reflections => Topic started by: C.W. Herndon on July 03, 2012, 12:55:04 PM
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I have been looking at the control box for the RDF Loop Antenna and discovered there are three different ones shown in the Purdue pictures.
First is the one shown in the cockpit. Picture one at bottom.
http://earchives.lib.purdue.edu/u?/earhart,808 (http://earchives.lib.purdue.edu/u?/earhart,808)
Second is the one shown in a picture of AE and E. Jay Quinby of the Western Electric Company. (This one is very similar to the one shown in the cockpit picture.) Picture 2 below.
http://earchives.lib.purdue.edu/u?/earhart,228 (http://earchives.lib.purdue.edu/u?/earhart,228)
Lastly, one in a picture of AE sitting, holding the loop assembly and some "unidentified man" holding a Bendix control unit. The caption for the picture says the man is "probably Harry Manning" but if it is, this is the first picture I have seen of him in which he is wearing glasses. Picture 3 below.
http://earchives.lib.purdue.edu/u?/earhart,913 (http://earchives.lib.purdue.edu/u?/earhart,913)
Very curious. Wonder which one was actually in the aircraft when they left Miami.
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I have been looking at the control box for the RDF Loop Antenna and discovered there are three different ones shown in the Purdue pictures.
Woody,
The first two photos in your attachment are both of the remote control unit for the Western Electric 20B receiver. (Red lines in the attachment to this post indicate how the photographs are oriented relative to one another.)
Your third photo shows Cyril Remmlein holding a Bendix loop antenna coupler. (See my 4 Dec 11 post (http://tighar.org/smf/index.php/topic,504.msg6949.html#msg6949) relating to this.)
Chuck
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Thanks for filling me in Chuck. Every day I discover things that are unfamiliar to me even though I thought I had read everything. Way too much to absorb in one reading so I have started over.
The biggest problem I had with the first two pictures was that some of the knobs did not seem to be the same. They still don't but that is not a big deal.
Was the Bendix unit, maybe, what was supposed to give them the ability to "home in" on stations in the higher frequency bands? I noticed that the Bendix unit had a switch labeled "Band" with options for 1, 2, 3, 4, and 5. Do we know if it was still installed when they left Miami?
Who was Cyril Remmien? I tried "Search TIGHAR" and got nothing.
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Was the Bendix unit, maybe, what was supposed to give them the ability to "home in" on stations in the higher frequency bands? I noticed that the Bendix unit had a switch labeled "Band" with options for 1, 2, 3, 4, and 5. Do we know if it was still installed when they left Miami?
What "Bendix unit" are you asking about and describing?
Who was Cyril Remmien? I tried "Search TIGHAR" and got nothing.
Did you search for Cyril “Remmien” instead of Cyril Remmlein? According Amelia Earhart: The Mystery Solved, by Elgin and Marie Long, Cyril D. Remmlein worked in the Radio Research Division of Bendix. (My identification of him as the gent in your third attachment came from a caption for the same photo appearing in the Long’s book.)
Chuck
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Hi Chuck. I was talking about the Bendix Loop Control in the 3rd picture of my first post and shown again here.
Yes, I mispelled the name. I will try again. My eyes are not as good as they used to be especially with the "i" and "l".
Thanks again. Maybe I will get it right this time.
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Hi Chuck. I was talking about the Bendix Loop Control in the 3rd picture of my first post and shown again here.
OK, thanks, Woody.
Was the Bendix unit, maybe, what was supposed to give them the ability to "home in" on stations in the higher frequency bands?
Well, if there was an ability to home on stations in the “higher frequency bands”—and I interpret those words to mean something in the HF range—and if the only receiver aboard was a general purpose type, then a unit like it was necessary to mate the loop to the receiver.
Do we know if it was still installed when they left Miami?
No.
Chuck
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Chuck, I was just trying to think of some reason why AE apparently thought she could home in on the higher frequencies that she could tune in on her radio receiver. It was obvious, from previous discussions, that learning how to use her RDF was not one of her highest priorities.
Is there any reason to think that the Bendix Loop Coupler might have allowed her to do this if she had known how to properly use the RDF system?
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Chuck, I was just trying to think of some reason why AE apparently thought she could home in on the higher frequencies that she could tune in on her radio receiver.
That, to me, is one of the $64,000 dollar questions.
Unfortunately, I haven't seen an answer to it anywhere.
Note the discrepancies:
June 25th at 2245GMT, the Coast Guard San Francisco office sent a radio message
... Mr. Putnam now at Oakland and advises Ms. Earhart at Bandoeng Java for repairs to motors and departure indefinite.
She will cable details communications from Port Darwin direct San Francisco and you will be given all information immediately. All communications from plane will be on 500, 3105, or 6210 kHz by voice, positions being given at 15 and 45 minutes past the hour. Itasca adjust transmitter for possible use 3105 kHz for voice. Direction finder on plane covers range of about 200 to 1400 kHz.
At 0720GMT, June 26th, Earhart cabled:
...Itasca transmit letter A, position, own call letters, as above on half hour at 7.5 MHz. Position ships and our leaving will determine broadcast times specifically. If frequencies mentioned unsuitable night work inform me at Lae. I will give long call by voice 3105 kHz quarter after hour, possible quarter to.
This contradicts the June 25th telegram that position reports would be given "given at 15 and 45 minutes past the hour."
Jacobson (http://tighar.org/wiki/Jacobson): "It is unclear why Earhart wants the Itasca to broadcast at 7500 kHz, since she is asking for code and cannot use that frequency for direction finding. The actual wording in the telegram is 7.5 megacycles."
At 1930GMT, June 26th, the San Francisco office of the USCG sent out a priority radio message stating
Following information from Earhart this date quote homing device covers from 200 to 1500 and 2400 to 4800 kHz any frequencies not repeat not near ends of bands suitable unquote. ... assume continuous signals after her direction finder in range. See broadcast on quarter after and quarter before hour on 6210 and 3105 kHz. Am advising Earhart that Itasca will voice radio her on 3105 on hour and half hour as she approaches Howland. ... Advice priority if adjustments Tare ten transmitter satisfactory for use on 3105.
The information on the 25th was that Earhart's DF equipment operated between 200 and 1400 kHz; now two ranges are given: "200 to 1500 and 2400 to 4800 kHz."
Jacobson (http://tighar.org/wiki/Jacobson): "There is no contemporaneous documentation to verify that the information regarding the double frequency band of Earhart's RDF came from Earhart or George Putnam. Based upon the quoted passage, it should be taken at face value and accepted as coming from Earhart."[9] (http://tighar.org/wiki/Failure_to_communicate#cite_note-8)
The transmission timeline (http://tighar.org/wiki/Transmission_timeline) shows that she asked for the letter A to be transmitted on 7500 kcs at 1928. At 1930, she reports that she heard the transmission, but could not get a null on it. This is the only transmission she acknowledges hearing from the Itasca.
All I'm doing here is providing background for your question. Why didn't she understand her equipment?
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Chuck, I was just trying to think of some reason why AE apparently thought she could home in on the higher frequencies that she could tune in on her radio receiver.
That, to me, is one of the $64,000 dollar questions.
Unfortunately, I haven't seen an answer to it anywhere.
All I'm doing here is providing background for your question. Why didn't she understand her equipment?
Marty, thanks for verification of my understanding of her of ability to properly use her equipment and her lack of understanding of its limitations. I was curious as to whether or not someone might have found anything new but didn't much expect it.
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Marty, thanks for verification of my understanding of her of ability to properly use her equipment and her lack of understanding of its limitations. I was curious as to whether or not someone might have found anything new but didn't much expect it.
Barring the discovery of a new cache of documents from someone who gave her advice along the way, I doubt we'll be able to answer the question.
So far as I can tell, with the materials we have in hand, we have an excellent question that we can't answer. :(
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Hi Chuck. I was talking about the Bendix Loop Control in the 3rd picture of my first post and shown again here.
Yes, I mispelled the name. I will try again. My eyes are not as good as they used to be especially with the "i" and "l".
Thanks again. Maybe I will get it right this time.
The reason the control box is so complicated is that it incorporated a way to resolve the 180° ambiguity. This required that you adjust the tuning controls on the control box so that the signal strength of the signals from the loop antenna were exactly as strong as the signals on the sense antenna (the belly antenna?) You can ignore doing this and just deal with the ambiguity the old fashioned way, by using your brain. I asked Brandenburg what would be the indications if the sense antenna were missing and Earhart attempted to use the control box in this fashion, so far, no response. The RDF was not designed to work on 7,500 kcs but, in case if might have worked in a very degraded fashion on this frequency, then Earhart's not knowing how to use the control box and to try it in the ambiguity mode may have been yet an additional reason why she could not get a null.
(I don't know why Bendix introduced this complication because it is child's play to resolve the ambiguity without it. Pilots, who come equipped with brains, have no problem so such circuits are only necessary of ADFs (automatic direction finders, an automatic RDF) because they do not have brains and cannot use external information to resolve he ambiguity.)
gl
gl
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Thanks Gary. I had not previously found anything about the function of the Bendix loop coupler. Apparently AE did hear something, a series of dashes if I remember correctly, on 7,500 kcs. Presumedly the signal was picked up either through the loop or, maybe, the sense antenna but once again she "could not get a null". Sounds like a familiar problem.
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(originally from pictures of interest thread (http://tighar.org/smf/index.php/topic,863.msg16846.html#msg16846))
"...Is this how long the wire runs between the transmitter and box?"
The "wire" seen in the photo (http://tighar.org/smf/index.php?action=dlattach;topic=863.0;attach=3540) runs from the antenna to the antennna controller (in the man's hands in Randy's pictures at the top of this thread). The Receiver, not the transmitter, connected to the controller, and through it to the antenna. The loop antenna was only used for receiving. The controller was mounted on the instrument panel, where it stuck out in a convenient place for Amelia to operate it (I'll try to find the photo). The controller rotated the antenna and indicated what direction the antenna was pointing. It also allowed the number of turns of wire inside the antenna to be selected for best frequency sensitivity.
Correction - a normally reliable source tells me that the controller only provided tuning of the coil, using capacitors, and such. Rotation must have been by other means, possibly a handle sticking out from the antenna through the cabin roof. I was confused by the knob in the middle of the control box, thinking it somehow rotated the antenna.
Nice clear view of Amelia's shoe.
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(originally from pictures of interest thread (http://tighar.org/smf/index.php/topic,863.msg16846.html#msg16846))
Correction - a normally reliable source tells me that the controller only provided tuning of the coil, using capacitors, and such.
Your source might also have told you that loop tuning was only one function of the box. As I indicated in comments to the original version of your post, the box is a locally controlled loop coupler, where “locally controlled” means that functions must be selected at the box (not remotely), and “loop coupler” primarily refers to providing means of coupling the loop and sense antennas for unilateral direction finding--but can also refer to coupling the loop antenna to the receiver input.
Rotation must have been by other means, possibly a handle sticking out from the antenna through the cabin roof. I was confused by the knob in the middle of the control box, thinking it somehow rotated the antenna.
Zoom this photo (http://earchives.lib.purdue.edu/cdm4/item_viewer.php?CISOROOT=%2Fearhart&CISOPTR=913&DMSCALE=12.5&DMWIDTH=600&DMHEIGHT=600&DMMODE=viewer&DMFULL=0&DMX=68&DMY=0&DMTEXT=&DMTHUMB=1&REC=1&DMROTATE=0&x=303&y=243) and you can see that there’s a hand wheel for turning the loop in Amelia’s left hand and that the knob in the center of the box is marked LOOP TUNING.
Chuck
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Thanks Chuck - I hadn't noticed that there was a turning knob on the bottom of the loop antenna assembly. It would have been inside the cockpit, above and to the right of Amelia's head, where her right hand could have easily turned it. Good observation.
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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
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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
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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
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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 (http://tighar.org/Projects/Earhart/Archives/Research/Bulletins/53_MiamiPhoto/53_MiamiPhoto.htm)
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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 (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
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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 (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 couple (http://earchives.lib.purdue.edu/cgi-bin/getimage.exe?CISOROOT=/earhart&CISOPTR=913&DMSCALE=100.00000&DMWIDTH=600&DMHEIGHT=600&DMX=2284&DMY=2632&DMTEXT=&REC=1&DMTHUMB=1&DMROTATE=0)r. 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
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Here is a link to an enlarged image of Earhart's coupler (http://earchives.lib.purdue.edu/cgi-bin/getimage.exe?CISOROOT=/earhart&CISOPTR=913&DMSCALE=100.00000&DMWIDTH=600&DMHEIGHT=600&DMX=2284&DMY=2632&DMTEXT=&REC=1&DMTHUMB=1&DMROTATE=0). 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
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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
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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 (http://tighar.org/smf/index.php/topic,504.msg6949.html#msg6949), 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.
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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 (http://earchives.lib.purdue.edu/cdm4/item_viewer.php?CISOROOT=%2Fearhart&CISOPTR=913&DMSCALE=50&DMWIDTH=600&DMHEIGHT=600&DMMODE=viewer&DMFULL=0&DMX=932&DMY=1162&DMTEXT=%2520b13f12i4&DMTHUMB=1&REC=1&DMROTATE=0&x=340&y=275):
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
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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.
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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
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Great find Gary! What an ironic picture considering what happened shortly afterwards.
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Has anyone seen this picture from the Smithsonian?
http://timeandnavigation.si.edu/multimedia-asset/amelia-earhart-holding-bendix-radio-direction-finder-loop-antenna (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" (https://tighar.org/wiki/Direction_finding) article.
(https://tighar.org/aw/mediawiki/images/2/20/Shoe9.jpg)
Probably the same photo shoot.
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... and in this Forum post (https://tighar.org/smf/index.php/topic,863.msg16839.html#msg16839)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.
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A blogger at immortalpancake.blogspot.com posted a photo by Albert Bresnik of AE and a man identified as Cyril Remlin from Bendix Corp. holding a loop and loop coupler. Remlin was probably the person guessed to be Manning in the Purdue photo discussed by Gary, Woody, Chuck et al. in this thread.
Dan Brown, #2408
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Recall that there were two different direction finders. The first was the Hooven-Bendix with the faired housing, installed in October, 1936, apparently while the plane was at Purdue. (The Timeline photo of Nov 21 shows the faired housing above the cabin.) That DF was removed in early March 1937, when the Bendix model with the large loop over the cockpit was installed, before the first round-the-world attempt.
The Ameliapedia article entitled "NR16020 Antennas" https://tighar.org/wiki/NR16020_antennas (https://tighar.org/wiki/NR16020_antennas) is a valuable source for sorting out the history of the various antennas and their probable functions.
See the Timeline document, March 3, 1937, for a news report with some details about the second DF set-up. The loop and coupler in the photo you cite appear to be the equipment installed then, in early March.
Concerning that early March news report and others, it was also printed in the Oakland Tribune paper, which is available via Newspapers.com, a subscription service, or using this link:
https://www.newspapers.com/clip/7681392/first_try_preps_dateline_burbank_mar/ (https://www.newspapers.com/clip/7681392/first_try_preps_dateline_burbank_mar/)