Radio equipment on NR16020 - Revision history

Moleski: /* Direction finding receiver */

2026-03-17T20:48:22Z

Direction finding receiver

← Older revision		Revision as of 20:48, 17 March 2026
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	== [[Direction finding]] receiver ==		== [[Direction finding]] receiver ==

	The [[Hooven Radio Compass]] was installed for a short time, but was removed and replaced by the [[loop antenna]] to save weight.<ref>[[Hooven]]</ref> [https://tighar.org/Projects/Earhart/Research/Bulletins/53_MiamiPhoto/53_MiamiPhoto.htm Careful analysis of photographs that can be dated] suggests that after the Hooven Radio Compass was removed, no other receiver took its place.		The [[Hooven Radio Compass]] was installed for a short time, but was removed and replaced by the [[loop antenna]] to save weight.<ref>[[Hooven]]</ref> [https://tighar.org/Projects/Earhart/Archives/Research/Bulletins/53_MiamiPhoto/53_MiamiPhoto.htm Careful analysis of photographs that can be dated] suggests that after the Hooven Radio Compass was removed, no other receiver took its place.

	== References ==		== References ==

Moleski: /* Direction finding receiver */

2026-03-17T20:45:11Z

Direction finding receiver

← Older revision		Revision as of 20:45, 17 March 2026
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	== [[Direction finding]] receiver ==		== [[Direction finding]] receiver ==

	The [[Hooven Radio Compass]] was installed for a short time, but was removed and replaced by the [[loop antenna]] to save weight.<ref>[[Hooven]]</ref> [~~http~~://tighar.org/Projects/Earhart/Research/Bulletins/53_MiamiPhoto/53_MiamiPhoto.htm Careful analysis of photographs that can be dated] suggests that after the Hooven Radio Compass was removed, no other receiver took its place.		The [[Hooven Radio Compass]] was installed for a short time, but was removed and replaced by the [[loop antenna]] to save weight.<ref>[[Hooven]]</ref> [https://tighar.org/Projects/Earhart/Research/Bulletins/53_MiamiPhoto/53_MiamiPhoto.htm Careful analysis of photographs that can be dated] suggests that after the Hooven Radio Compass was removed, no other receiver took its place.

	== References ==		== References ==

Moleski: /* Bendix direction finding coupler */

2026-02-04T14:00:22Z

Bendix direction finding coupler

← Older revision		Revision as of 14:00, 4 February 2026
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	=== Bendix [[direction finding]] coupler ===		=== Bendix [[direction finding]] coupler ===

	[[Ric Gillespie]]: "I think there was a Bendix device aboard the aircraft that allowed the loop to be used with the Western Electric 20B receiver. I think it was integral to the Bendix MN-5 [[loop]] and was the same device described on page 42 of the August 1937 issue of Aero Digest magazine. Under the heading "Aero Radio Digest - The Newest Developments in the ~~Filed~~ of Aircraft Radio" the first article is entitled "Bendix D-Fs". I quote: 'Bendix D-Fs are designed to operate in conjunction with Bendix Type RA-1 receiver, but will also give accurate and dependable bearings when used with any standard radio receiver covering the desired frequency range.'"<ref>25 February 2009 [[AESF\| Forum]].</ref>		[[Ric Gillespie]]: "I think there was a Bendix device aboard the aircraft that allowed the loop to be used with the Western Electric 20B receiver. I think it was integral to the Bendix MN-5 [[loop]] and was the same device described on page 42 of the August 1937 issue of Aero Digest magazine. Under the heading "Aero Radio Digest - The Newest Developments in the Field of Aircraft Radio" the first article is entitled "Bendix D-Fs". I quote: 'Bendix D-Fs are designed to operate in conjunction with Bendix Type RA-1 receiver, but will also give accurate and dependable bearings when used with any standard radio receiver covering the desired frequency range.'"<ref>25 February 2009 [[AESF\| Forum]].</ref>

	;[[Ric Gillespie]], [[Finding Amelia]], p.64.		;[[Ric Gillespie]], [[Finding Amelia]], p.64.

Moleski: /* Some TIGHAR researchers say 'no' */

2011-07-16T12:16:15Z

Some TIGHAR researchers say 'no'

← Older revision		Revision as of 12:16, 16 July 2011
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	:According to the schematic of the transmitter which TIGHAR has published, and which I am now researching, the transmitter had NO MCW (Modulated CW) capability. Modulated CW is either generated by a tone which modulates the carrier, which is, in essence, simply an AM signal modulated with the tone, and would have no distance advantage over AM. because of the power taken up by the carrier and both sidebands (this is of course, why SSB (Single Sideband) is the voice transmission choice of today, because by suppressing the unwanted sideband and the carrier, one gains 75 percent more power out than with AM phone.		:According to the schematic of the transmitter which TIGHAR has published, and which I am now researching, the transmitter had NO MCW (Modulated CW) capability. Modulated CW is either generated by a tone which modulates the carrier, which is, in essence, simply an AM signal modulated with the tone, and would have no distance advantage over AM. because of the power taken up by the carrier and both sidebands (this is of course, why SSB (Single Sideband) is the voice transmission choice of today, because by suppressing the unwanted sideband and the carrier, one gains 75 percent more power out than with AM phone.

	:The other method of MCW generation is by using a "chopper" which interrupts the carrier at a rapid rate. This method "fools" the receiver into believing it is demodulating a AM signal, while still retaining the 100 percent pure carrier. When MF and LF "ruled the airwaves", all emergency radio transmitters were required to be equipped for the transmission of MCW since the transmission could be received on any radio capable of tuning the frequencies involved. A pure CW signal will not be recognized except by a "thunk" as the speaker magnet pulls the cone in when the carrier is on, it produces no tone of its own. The receiver used by Earhart had what was then referred to as a "CW oscillator", today it is called a BFO, or Beat Frequency Oscillator. This device generates a signal slightly off from whatever IF frequency is used in the receiver, and is tunable. When a CW signal is received, this additive offset from the BFO of "CW oscillator" generates a tone for speaker or headset listening. This is plainly shown in the receiver schematic, although the tube used in the oscillator is unknown. The whole point of MCW is rendered moot, however, because, even though the transmitter theoretically maintained provision for CW, the key and microphone transfer switch were removed prior to the last flight, along with the trailing wire, the Gurr load coil, etc, etc. If one looks at the schematic, one will notice that the additional relay for grid block keying was still there, but it wouldn't have worked using the microphone to key the transmitter. In the original configuration, when the transfer switch was set to "CW" the dynamotor was switched to constant run, and the 3rd relay provided grid block keying for the transmitter. This was a compromise at best, as there was no break in capability, wherein there is an antenna relay which automatically switches from TX to RX during key up periods, or of course, when the mode switch was shifted back to "phone" which, in the setup described in the schematic, was the switchology required to go from transmit to receive.		:The other method of MCW generation is by using a "chopper" which interrupts the carrier at a rapid rate. This method "fools" the receiver into believing it is demodulating a AM signal, while still retaining the 100 percent pure carrier. When MF and LF "ruled the airwaves", all emergency radio transmitters were required to be equipped for the transmission of MCW since the transmission could be received on any radio capable of tuning the frequencies involved. A pure CW signal will not be recognized except by a "thunk" as the speaker magnet pulls the cone in when the carrier is on, it produces no tone of its own. The receiver used by Earhart had what was then referred to as a "CW oscillator", today it is called a BFO, or Beat Frequency Oscillator. This device generates a signal slightly off from whatever IF frequency is used in the receiver, and is tunable. When a CW signal is received, this additive offset from the BFO of "CW oscillator" generates a tone for speaker or headset listening. This is plainly shown in the receiver schematic, although the tube used in the oscillator is unknown. The whole point of MCW is rendered moot, however, because, even though the transmitter theoretically maintained provision for CW, the key and microphone transfer switch were removed prior to the last flight, along with the trailing wire, the Gurr load coil, etc, etc. If one looks at the schematic, one will notice that the additional relay for grid block keying was still there, but it wouldn't have worked using the microphone to key the transmitter. In the original configuration, when the transfer switch was set to "CW" the [[dynamotor]] was switched to constant run, and the 3rd relay provided grid block keying for the transmitter. This was a compromise at best, as there was no break in capability, wherein there is an antenna relay which automatically switches from TX to RX during key up periods, or of course, when the mode switch was shifted back to "phone" which, in the setup described in the schematic, was the switchology required to go from transmit to receive.

	:Even had there been a antenna relay, or an MCW osc or chopper, it would have still proven useless since neither AE or Noonan cared about CW or were in any way proficient in the use thereof. I believe that the radio operator license issued to AE waa a "Gimme" because there simply is no way she could have copied the requisite speed of Morse required even for a Third Class Radiotelegraph license. Now, the Itasca most likely had MCW capability on all frequencies, and thus would have been heard even if the switch was in the "phone" position....I also don't see where the "CW oscillator" was removed from the transmitter. Maybe it was disabled during the refit when the rest of the components required for Morse were removed. If it were still present, signals sent on 3105 in A1 [CW/Morse code] could have been received by the aircraft.		:Even had there been a antenna relay, or an MCW osc or chopper, it would have still proven useless since neither AE or Noonan cared about CW or were in any way proficient in the use thereof. I believe that the radio operator license issued to AE waa a "Gimme" because there simply is no way she could have copied the requisite speed of Morse required even for a Third Class Radiotelegraph license. Now, the Itasca most likely had MCW capability on all frequencies, and thus would have been heard even if the switch was in the "phone" position....I also don't see where the "CW oscillator" was removed from the transmitter. Maybe it was disabled during the refit when the rest of the components required for Morse were removed. If it were still present, signals sent on 3105 in A1 [CW/Morse code] could have been received by the aircraft.

Rickerjones: /* Design */ add image

2011-06-14T21:41:34Z

Design: add image

← Older revision		Revision as of 21:41, 14 June 2011
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	=== Design ===		=== Design ===
			[[Image:WE_631B_Microphone(Courtesy,_NWA_History_Centre,_Inc.).jpg‎ \|200px\|thumb\|right\|<div align="center">Earhart's Electra was equipped with two Western Electric 631B microphones, as listed in the Luke Field inventory. The WE 631B was a carbon button microphone used with the WE 13C transmitter. (Courtesy: NWA History Centre, Inc.)</div>]]
	"The Western Electric Model 13C radio transmitter was a fifty-watt output, crystal-controlled unit. The original design of this transmitter produced amplitude-modulated (A-M) voice (A3 emission) signals only. The transmitter aboard NR16020 was factory-modified to incorporate Morse code (C-W) transmission capability (A1 emission) as well.		"The Western Electric Model 13C radio transmitter was a fifty-watt output, crystal-controlled unit. The original design of this transmitter produced amplitude-modulated (A-M) voice (A3 emission) signals only. The transmitter aboard NR16020 was factory-modified to incorporate Morse code (C-W) transmission capability (A1 emission) as well.

	"Model 13C was the factory designation for a three-frequency transmitter operating in the 2500-6500 KHz range. A 1939 source (Morgan) illustrates a Model 13CB, a three-frequency radio with C-W and low-frequency (325-500 KHz) capability. Earhart’s Model 13C was factory-modified to include 500 KHz operation, and was probably the prototype for this later off-the-shelf version."<ref>[[Mike Everette]], [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>		"Model 13C was the factory designation for a three-frequency transmitter operating in the 2500-6500 KHz range. A 1939 source (Morgan) illustrates a Model 13CB, a three-frequency radio with C-W and low-frequency (325-500 KHz) capability. Earhart’s Model 13C was factory-modified to include 500 KHz operation, and was probably the prototype for this later off-the-shelf version."<ref>[[Mike Everette]], [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>

	"AE’s rig worked from 12 volt DC power."<ref>6 September 2000 [http://www.tighar.org/Projects/Earhart/forum/Highlights101_120/highlights104.html Forum.]</ref>		"AE’s rig worked from 12 volt DC power."<ref>6 September 2000 [http://www.tighar.org/Projects/Earhart/forum/Highlights101_120/highlights104.html Forum.]</ref>

	=== Selecting transmission bands ===		=== Selecting transmission bands ===

Moleski: /* Bendix direction finding coupler */

2011-04-05T18:28:57Z

Bendix direction finding coupler

← Older revision		Revision as of 18:28, 5 April 2011
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	[[Ric Gillespie]]: "I think there was a Bendix device aboard the aircraft that allowed the loop to be used with the Western Electric 20B receiver. I think it was integral to the Bendix MN-5 [[loop]] and was the same device described on page 42 of the August 1937 issue of Aero Digest magazine. Under the heading "Aero Radio Digest - The Newest Developments in the Filed of Aircraft Radio" the first article is entitled "Bendix D-Fs". I quote: 'Bendix D-Fs are designed to operate in conjunction with Bendix Type RA-1 receiver, but will also give accurate and dependable bearings when used with any standard radio receiver covering the desired frequency range.'"<ref>25 February 2009 [[AESF\| Forum]].</ref>		[[Ric Gillespie]]: "I think there was a Bendix device aboard the aircraft that allowed the loop to be used with the Western Electric 20B receiver. I think it was integral to the Bendix MN-5 [[loop]] and was the same device described on page 42 of the August 1937 issue of Aero Digest magazine. Under the heading "Aero Radio Digest - The Newest Developments in the Filed of Aircraft Radio" the first article is entitled "Bendix D-Fs". I quote: 'Bendix D-Fs are designed to operate in conjunction with Bendix Type RA-1 receiver, but will also give accurate and dependable bearings when used with any standard radio receiver covering the desired frequency range.'"<ref>25 February 2009 [[AESF\| Forum]].</ref>

			;[[Ric Gillespie]], [[Finding Amelia]], p.64.
			:Just what range of frequencies the Electra’s homing device could cover is an important question but not a difficult one to answer. A hoop-shaped “loop” antenna mounted above the Electra’s cockpit received the signals for direction finding. Numerous photos taken from the time of its installation just prior to Earhart’s first world flight attempt in March until the final takeoff from Lae, New Guinea, in July leave no doubt that the loop antenna on Earhart’s Electra was one of a new line of Bendix direction finders pictured and described in the August 1937 issue of Aero Digest magazine: “Bendix D-Fs are designed to operate in conjunction with Bendix Type RA-1 receiver, but will also give accurate and dependable bearings when used with any standard radio receiver covering the desired frequency range.” The article also notes that these receivers can be used “as navigational direction finding instruments within frequency range of 200–1500 kilocycles.”<ref>“Bendix D-Fs,” Aero Digest (August 1937): 42.</ref> Those parameters generally agree with the limits described by Manning and Miller prior to the first world flight attempt (“Plane has direction finder covering 200 to 1430 kcs”).<ref>COMFRANDIV to Shoshone, March 13, 1937.</ref> They also agree with Putnam’s message of June 25, 1937, saying that the plane’s direction finder “covers range of about 200 to 1400 kilocycles.”<ref>COMFRANDIV to Itasca, June 25, 1937.</ref> Where Earhart got the idea that her direction finder could cover “from 200 to 1500 and 2400 to 4800 kilocycles” is not clear, but the signals she requested on 7500 kilocycles were far beyond even those limits.<ref>COMFRANDIV to Itasca, June 26, 1937.</ref>

	=== Difficulties using the receiver ===		=== Difficulties using the receiver ===

Moleski: /* Related articles */

2009-10-13T21:23:11Z

← Older revision		Revision as of 21:23, 13 October 2009
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	* [http://www.tighar.org/Projects/Earhart/Research/ResearchPapers/Brandenburg/WE-13.htm WE-13C Transmitter Harmonic Power Output.]		* [http://www.tighar.org/Projects/Earhart/Research/ResearchPapers/Brandenburg/WE-13.htm WE-13C Transmitter Harmonic Power Output.]
	* [[NR16020 antennas]].		* [[NR16020 antennas]].
			* [[Radio chronology]].
	* [[Modifications by Joe Gurr]]--prior to [[first attempt]], probably in January-February 1937.		* [[Modifications by Joe Gurr]]--prior to [[first attempt]], probably in January-February 1937.

	<!-- Please leave this category marker at the bottom. You may add this article to other categories if you wish -->		<!-- Please leave this category marker at the bottom. You may add this article to other categories if you wish -->
	[[Category:Radio considerations]]		[[Category:Radio considerations]]

Moleski at 21:22, 13 October 2009

2009-10-13T21:22:14Z

Show changes

Moleski at 17:31, 13 October 2009

2009-10-13T17:31:10Z

← Older revision		Revision as of 17:31, 13 October 2009
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	"Model 13C was the factory designation for a three-frequency transmitter operating in the 2500-6500 KHz range. A 1939 source (Morgan) illustrates a Model 13CB, a three-frequency radio with C-W and low-frequency (325-500 KHz) capability. Earhart’s Model 13C was factory-modified to include 500 KHz operation, and was probably the prototype for this later off-the-shelf version."<ref>[[Mike Everette]], [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>		"Model 13C was the factory designation for a three-frequency transmitter operating in the 2500-6500 KHz range. A 1939 source (Morgan) illustrates a Model 13CB, a three-frequency radio with C-W and low-frequency (325-500 KHz) capability. Earhart’s Model 13C was factory-modified to include 500 KHz operation, and was probably the prototype for this later off-the-shelf version."<ref>[[Mike Everette]], [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>

	"AE’s rig worked from 12 volt DC power."<ref>6 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum.]</ref>		"AE’s rig worked from 12 volt DC power."<ref>6 September 2000 [http://www.tighar.org/Projects/Earhart/forum/Highlights101_120/highlights104.html Forum.]</ref>

	=== Selecting transmission bands ===		=== Selecting transmission bands ===
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	;[[Mike Everette]] thought not.		;[[Mike Everette]] thought not.
	"AE’s rig did NOT have "[[MCW]]" capability (that is, A2 emission, tone modulated telegraphy). It only transmitted [[CW\| A1 (unmodulated, on-off keyed telegraphy)]] and [[voice\| A3 (amplitude modulated voice)]]" ([[Mike Everette]], 6 September 2000, [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum).]		"AE’s rig did NOT have "[[MCW]]" capability (that is, A2 emission, tone modulated telegraphy). It only transmitted [[CW\| A1 (unmodulated, on-off keyed telegraphy)]] and [[voice\| A3 (amplitude modulated voice)]]" ([[Mike Everette]], 6 September 2000, [http://www.tighar.org/Projects/Earhart/forum/Highlights101_120/highlights104.html Forum).]

	;Greg Moore, 28 Jun 2004 [http://www.tighar.org/forum/Forum_Archives/200406.txt Forum.]		;Greg Moore, 28 Jun 2004 [http://www.tighar.org/Projects/Earhart/forum/Forum_Archives/200406.txt Forum.]

	:According to the schematic of the transmitter which TIGHAR has published, and which I am now researching, the transmitter had NO MCW (Modulated CW) capability. Modulated CW is either generated by a tone which modulates the carrier, which is, in essence, simply an AM signal modulated with the tone, and would have no distance advantage over AM. because of the power taken up by the carrier and both sidebands (this is of course, why SSB (Single Sideband) is the voice transmission choice of today, because by suppressing the unwanted sideband and the carrier, one gains 75 percent more power out than with AM phone.		:According to the schematic of the transmitter which TIGHAR has published, and which I am now researching, the transmitter had NO MCW (Modulated CW) capability. Modulated CW is either generated by a tone which modulates the carrier, which is, in essence, simply an AM signal modulated with the tone, and would have no distance advantage over AM. because of the power taken up by the carrier and both sidebands (this is of course, why SSB (Single Sideband) is the voice transmission choice of today, because by suppressing the unwanted sideband and the carrier, one gains 75 percent more power out than with AM phone.
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	=== Tuning the receiver ===		=== Tuning the receiver ===
	"The receiver was not 'crystal controlled' but was hand-tuned by selecting the correct 'band' and then turning a wee crank until the desired frequency 'came in.' ... The 20B receiver and the 27A remote that goes with it are described in a ... Western Electric sales bulletin published in September 1936 entitled "An All-Purpose Radio Receiver for Mobile Applications" by K. O Thorp, Radio Development Department."<ref>[[Ric Gillespie]], 21 June 2000 [http://www.tighar.org/forum/Highlights81_100/highlights93.html Forum.]</ref>		"The receiver was not 'crystal controlled' but was hand-tuned by selecting the correct 'band' and then turning a wee crank until the desired frequency 'came in.' ... The 20B receiver and the 27A remote that goes with it are described in a ... Western Electric sales bulletin published in September 1936 entitled "An All-Purpose Radio Receiver for Mobile Applications" by K. O Thorp, Radio Development Department."<ref>[[Ric Gillespie]], 21 June 2000 [http://www.tighar.org/Projects/Earhart/forum/Highlights81_100/highlights93.html Forum.]</ref>

	=== Bendix [[direction finding]] coupler ===		=== Bendix [[direction finding]] coupler ===
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	Date: 5/12/00		Date: 5/12/00
	From: Hue Miller		From: Hue Miller
	[http://www.tighar.org/forum/Highlights81_100/highlights87.html]		[http://www.tighar.org/Projects/Earhart/forum/Highlights81_100/highlights87.html]
	I have been rereading the radio logs at "logjam.html" site and the more I read, the more moved I am by how sad a story of confusion this is.		I have been rereading the radio logs at "logjam.html" site and the more I read, the more moved I am by how sad a story of confusion this is.

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	Date: 9/18/00		Date: 9/18/00
	From: Hue Miller		From: Hue Miller
	[http://www.tighar.org/forum/Highlights101_120/highlights106.html]--double check		[http://www.tighar.org/Projects/Earhart/forum/Highlights101_120/highlights106.html]--double check

	Vern writes:		Vern writes:
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	----		----

	[[Ric Gillespie]], June 21, 2000, [http://www.tighar.org/forum/Highlights81_100/highlights93.html Forum.]		[[Ric Gillespie]], June 21, 2000, [http://www.tighar.org/Projects/Earhart/forum/Highlights81_100/highlights93.html Forum.]

	1. When the airplane was delivered to AE in July 1936 it had a WE 13C transmitter and a WE 20B receiver, the same radios (or so it would seem) that it had when it disappeared. However, there was no dorsal antenna on the airplane at all. There was a belly antenna identical to the one that was apparently lost at Lae with a lead-in that entered the fuselage right under the copilot's seat where the 20B receiver was mounted. The only other antenna on the airplane was a trailing wire that deployed from the extreme tail of the airplane, just under the navigation light. At that time the airplane appears to have no DF capability at all.		1. When the airplane was delivered to AE in July 1936 it had a WE 13C transmitter and a WE 20B receiver, the same radios (or so it would seem) that it had when it disappeared. However, there was no dorsal antenna on the airplane at all. There was a belly antenna identical to the one that was apparently lost at Lae with a lead-in that entered the fuselage right under the copilot's seat where the 20B receiver was mounted. The only other antenna on the airplane was a trailing wire that deployed from the extreme tail of the airplane, just under the navigation light. At that time the airplane appears to have no DF capability at all.

Moleski at 23:17, 12 October 2009

2009-10-12T23:17:29Z

← Older revision		Revision as of 23:17, 12 October 2009
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	* [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]		* [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]
	* [http://www.tighar.org/Projects/Earhart/Documents/Hooven_Report/HoovenReport.html The Hooven Report.]		* [http://www.tighar.org/Projects/Earhart/Documents/Hooven_Report/HoovenReport.html The Hooven Report.]
	* [http://www.tighar.org/Projects/Earhart/ResearchPapers/Brandenburg/WE-13.htm WE-13C Transmitter Harmonic Power Output.]		* [http://www.tighar.org/Projects/Earhart/Research/ResearchPapers/Brandenburg/WE-13.htm WE-13C Transmitter Harmonic Power Output.]
	* [[NR16020 antennas]].		* [[NR16020 antennas]].
	* [[Modifications by Joe Gurr]]--prior to [[first attempt]], probably in January-February 1937.		* [[Modifications by Joe Gurr]]--prior to [[first attempt]], probably in January-February 1937.