TIGHAR

Amelia Earhart Search Forum => Radio Reflections => Topic started by: Bruce W Badgrow on July 25, 2014, 04:05:38 PM

Title: Earharts Radio Transmitter
Post by: Bruce W Badgrow on July 25, 2014, 04:05:38 PM
In a letter written on July 25, 1937 by Mr. Eric H. Chater, Manager of Guinea Airways, is the following paragraph

OUR WIRELESS OPERATOR REPORTS

THE CONDITION OF RADIO EQUIPMENT ON EARHART PLACE IS AS FOLLOWS - TRANSMITTER CARRIER WAVE ON 6210 KC's
WAS VERY ROUGH AND I ADVISED MISS EARHART TO PITCH HER VOICE HIGHER TO OVERCOME THE DISTORTION CAUSED BY THE ROUGH CARRIER WAVE, OTHERWISE THE TRANSMITTER SEEMED TO BE WORKING SATISFACTORILY.

From the above it appears that when Earhart arrived at Lae her radio transmitter was developing a problem. Mr. Chater detailed maintenance work that was done on the plane but he mentioned no work being done on the transmitter. So apparently the transmitter still had a rough carrier that distorted the voice modulation when Earhart took off for Howland Island. The Itasca radio operators had difficulty reading Earhart's transmission's. They attributed the distortion to the fact that her signals were so strong it caused their radio speakers to distort.

We can be certain that the very rough landing on the reef at Gardner Island didn't do Earhart's transmitter any good. I'm amazed that it even worked after the beating it probably took. All the transmissions heard after the landing appear to have been badly distorted. The operator on Nauru Island said it sounded like Earhart's voice but the signal was so badly distorted he couldn't understand a thing she said. The Pan Am operators heard numerous signals that were voice modulated by both male and female voices. They said the signals all had odd or wobbly modulation characteristics and they couldn't understand anything that was said.

The fact that Earhart's transmitter apparently was putting out a badly distorted signal helps sort out the post loss radio messages. Anyone who reported that they heard Amelia Earhart "loud and clear," in my opinion, wasn't listening to an Earhart transmission.

Bruce W Badgrow

Title: Re: Earharts Radio Transmitter
Post by: James Champion on July 25, 2014, 07:15:07 PM
Interesting that Eric Chatter reported the carrier wave was rough, and to pitch her voice higher. This indicates there may have been a lower-frequency distortion or signal being added within the transmitter itself.

I don't know about symptoms, problems, or failure modes of a dynamotor high voltage supply as used in her Western Eelectric transmitter, but if the dynamotor had a bad winding, it might (an assumption) cause a varying high voltage, modulating the signal seperately of the voice modulation. Maybe someone familiar with dynamotors could comment.

I know Betty Klenck Brown reported the signal as faiding in and out, but did she recall a similar distortion in the voices?
Title: Re: Earharts Radio Transmitter
Post by: John Ousterhout on July 26, 2014, 07:59:25 AM
I have some limited experience with dynamotor-powered WWII radios, but not with the specific kind used by Amelia.  The most obvious characteristic of a dynamotor is the time lag to reach full output - taking a full 1 to 2 seconds to spin up.   Amelia's radio was wired so the dynamotor was off until the microphone "talk" switch was pushed.  (Before the Morse code key was removed, the system had the option of running the dynamotor constantly, providing a constant supply of power to the transmitter for code transmission.)  This creates a characteristic rising whine heard at the start of each transmission, and tends to clip off anything said for the first half second or so.  To make transmissions clear, the technique taught is to key the mike, then wait a moment before speaking.
Dynamotors have commutator brushes, which can create a buzz or whine in the background if there isn't a filter, and especially if they're worn or dirty.
The war-era Dynamotors I'm familiar with had no explicit voltage regulation circuit. They relied on the load to even things out, but even so the voltage could change quite a bit.  This wasn't as big a problem for tube radios as one might expect - it meant a simpler circuit that worked well enough for general purposes.
The supply voltage also effected the output voltage.  If a dynamotor is running off of batteries, then the output voltage will decline as the battery supply voltage declines.  I'm not enough of an expert to be able to predict what the effect might be on Amelia's radio.
Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 26, 2014, 08:39:03 AM

We can be certain that the very rough landing on the reef at Gardner Island didn't do Earhart's transmitter any good.

Bruce W Badgrow

Bruce,

On what evidence are you basing an hard landing at Gardner island?

Title: Re: Earharts Radio Transmitter
Post by: James Champion on July 26, 2014, 08:51:56 AM
Quote
The most obvious characteristic of a dynamotor is the time lag to reach full output - taking a full 1 to 2 seconds to spin up.

That is interesting in terms of Amelia possibly doing morse code with the mike button. The first dot or dash after a pause might end up missing with slowly transmitted code.

I looked at the basic schematics some time back, and I seem to recall that the transmitter also had key'ed filaments in the tubes (tube cathode heaters are off until the mike button is pushed). Years ago I had a WWII surplus BC654 that was like this. I wondered at the time how this might have affected her morse code, possibly clipping a leading dash into a dot.
Title: Re: Earharts Radio Transmitter
Post by: Bruce W Badgrow on July 26, 2014, 04:49:23 PM
Tim, in a TIGHAR Tracks article "A landing on the Reef" there are three photos of the reef at Gardner Island. There weren't any big rocks on it but it still looks pretty rough to be used as a runway.

Bruce W Badgrow

Title: Re: Earharts Radio Transmitter
Post by: Clarence Carlson on July 26, 2014, 08:56:32 PM

The Itasca radio operators had difficulty reading Earhart's transmission's. They attributed the distortion to the fact that her signals were so strong it caused their radio speakers to distort.

I am a little unclear on this point. It does seem that the radio operators aboard Itasca had difficulty reading some of the transmissions from KHAQQ, but it appears mostly due to signals being too weak to copy. (I am thinking of those earlier signals when she was some ways out) Could you possibly site a reference to a time where it was reported that she was not understood by Itasca due to "distortion". That would be helpful.

Quote
All the transmissions heard after the landing appear to have been badly distorted. The operator on Nauru Island said it sounded like Earhart's voice but the signal was so badly distorted he couldn't understand a thing she said.


Having read over the post signals analysis it is not clear to me that "all" the signals were distorted. Which particular ones are you referencing?
When looking at the information we have on the reception from Radio Nauru it specifically states "voice not intelligible". It says nothing about distortion.
Unintelligible speech could be due to a number of things, including poor modulation of the underlying carrier signal.

Quote

The Pan Am operators heard numerous signals that were voice modulated by both male and female voices. They said the signals all had odd or wobbly modulation characteristics and they couldn't understand anything that was said.

I do recall reading a reception of some wobbly signals by Pan Am operators but not "all" of them. References here would be useful. I've been a ham operator for a long time and I am not clear about what "wobbly" means. Is a wobbly signal one that cannot be understood due to distortion? I'm not sure.

Quote
The fact that Earhart's transmitter apparently was putting out a badly distorted signal helps sort out the post loss radio messages. Anyone who reported that they heard Amelia Earhart "loud and clear," in my opinion, wasn't listening to an Earhart transmission.

It's my understanding that there were at least a few times, prior to losing radio contact, when her transmissions were received "loud and clear" (or something very close to that) by Itasca, pointing to effective transmissions under some conditions.  I support your work in attempting to find a way to separate the wheat from the chaff with these signals analysis, but I'm not quite sold on your final premise.

Title: Re: Earharts Radio Transmitter
Post by: Martin X. Moleski, SJ on July 27, 2014, 04:36:27 AM

I am a little unclear on this point. It does seem that the radio operators aboard Itasca had difficulty reading some of the transmissions from KHAQQ, but it appears mostly due to signals being too weak to copy. (I am thinking of those earlier signals when she was some ways out) Could you possibly site a reference to a time where it was reported that she was not understood by Itasca due to "distortion". That would be helpful.

I am not going to get into this argument.

I have put together a transmission timeline (http://tighar.org/wiki/Transmission_timeline) that summarizes all of the transmissions received from AE during the fatal flight.

That data may or may not help resolve this particular dispute, but I do believe it is the data needed for an informed discussion.
Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 27, 2014, 04:52:20 AM
Tim, in a TIGHAR Tracks article "A landing on the Reef" there are three photos of the reef at Gardner Island. There weren't any big rocks on it but it still looks pretty rough to be used as a runway.

Bruce W Badgrow

Many thanks.

Video evidence touts the putative touchdown area as being ideal in both length and surface.

Title: Re: Earharts Radio Transmitter
Post by: Roger London on July 27, 2014, 04:53:57 AM
All adventurers have back-up plans, just as Amelia did failing landfall at Howland she'd fly the pre-spcified 'north-south line'. Lamentably a plan not notified to sufficient, or sufficiently pertinent, people, or at least it was not coherently passed to those most involved. Today of course adventurers have 'Mission Control Centres'.

However there is much store attached to her radio communications good, bad, and indifferent, but non to an outright radio failure. It would seem reasonable to say had she known her radio had failed before reaching half-way to Howland she would have aborted and returned. But what if it failed nearer to Howland, would she and Itasca have intuitively expected and implemented 'plan B' - black smoke from Itasca, etc? All would now know the risk of missing Itasca would be great. More importantly, in failing to locate Howland wouldn't this have been when she justifiably and inherently expected all support personnel to know and respond to her survival plan to fly the 'north-south line' hopefully to an island. She may well have been under the loose expectation that a previously (but aborted) plan to construct an airstrip on Niku would probably be complete, or crash-landing usable? In ANY event wouldn't she, though frightened, have been blindly confident that search would follow her, WITHOUT fail? I purport she DID expect rescue from the north-south line even without radio communication, even for this survival recourse morse communication still did not enter her vital-requirement list. Basically if voice comms failed 'ground support' would prevail.

What a fantastic project, Roger
Title: Re: Earharts Radio Transmitter
Post by: Joe Cerniglia on July 27, 2014, 06:44:00 AM
Tim, in a TIGHAR Tracks article "A landing on the Reef" there are three photos of the reef at Gardner Island. There weren't any big rocks on it but it still looks pretty rough to be used as a runway.

Bruce W Badgrow

Many thanks.

Video evidence touts the putative touchdown area as being ideal in both length and surface.

Richard Gifford, a retired airline captain who personally examined the putative landing site on Niku in 2001, told me in 2011 that that area is scattered with numerous potholes, but "otherwise smooth."  A rough landing is certainly imaginable and Captain Gifford has speculated an airplane might sustain some damage.  The speculated landing area is good enough, but hardly "ideal."

Joe Cerniglia
TIGHAR #3078C


Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 27, 2014, 07:02:32 AM

Richard Gifford, a retired airline captain who personally examined the putative landing site on Niku in 2001, told me in 2011 that that area is scattered with numerous potholes, but "otherwise smooth."  A rough landing is certainly imaginable and Captain Gifford has speculated an airplane might sustain some damage.  The speculated landing area is good enough, but hardly "ideal."

Joe Cerniglia
TIGHAR #3078C

How do you envisage the balloon tyres' ability to offset the impact?

Title: Re: Earharts Radio Transmitter
Post by: JNev on July 27, 2014, 10:20:02 AM
They're gooshy-soft by comparison to conventional tires and have a large foot print so tend to 'average out' rough spots even as their resiliency absorbs protrusions and their size helps the craft 'float' over dimples, small and even fairly large.
Title: Re: Earharts Radio Transmitter
Post by: John Ousterhout on July 27, 2014, 12:32:56 PM
Those big tires would be called Tundra Tires (http://www.flyingmag.com/tundra-tire-nation) now days.  With empty tanks, the Lockheed would perform rather like an Alaska bush plane, which handle landing on river bars with rocks "as large as shoe boxes".  Amelia was planning for unimproved runways, rather than off-airport landings I assume.
Title: Re: Earharts Radio Transmitter
Post by: Joe Cerniglia on July 27, 2014, 02:08:35 PM
I am addressing the particular argument that landing conditions on the Nutiran shore (map)  (http://tighar.org/images/maps/nikuevidence.jpg)are ideal for landing an aircraft.  I am respectfully advancing the modest idea in its stead that landing conditions there are less than perfect but still survivable, with some possible damage to aircraft and its occupants.

We can talk about the Electra's tires and their marvelous ability to absorb shock, but consider:

1) Again, the area is studded with large potholes.

2) The worm gear on that particular Electra was not designed for force loading from the sides, as is caused by impact with a large pothole.  Photos of the tire (http://hawaii.gov/hawaiiaviation/publications/above-the-pacific-by-william-j-horvat-1966/images/EarhartTireBlewOut.jpg) at the Luke Field ground loop accident are instructive.

3) So far as I know the aircraft was not equipped with shoulder restraints.

The argument was advanced by Bruce that a landing on the Nutiran shore would have been rough.  I wasn't there to see it (if indeed it happened at all), but I find that narrow piece of his speculation reasonable.  The opposing idea that the conditions there were "ideal in both length and surface" and that a rough landing there is simply an unreasonable thought not to be entertained seems to me at odds with the facts as they have been communicated to me, by Captain Gifford, who, after all, was there, and by others.

They had to get the airplane down with all of the following intact for transmissions to be possible:  starboard prop, only generator (also on the starboard side), and a working fuel system from the tanks to the starboard engine.  There were doubtless a few other things the aircraft had to have working to do what it supposedly did, but beyond those minimum requirements, other damage to the aircraft must be admitted as readily possible as a direct result of the ground conditions.

Also to consider:

Captain Gifford is often quoted that he could land a 747 there but not take off again.  That implies to me either possible damage to the aircraft from landing it or subpar conditions on the takeoff field, or both.

Betty Brown and others who credibly intercepted radio transmissions said Noonan had been injured, perhaps in the landing.

Betty also told me in our telephone conversation that she thought she heard Earhart say "one engine is up."  She did not write this down in the diary but remembered it later.  Take this as a recalled memory from one who heard it, only this and nothing more.

I find the narrow argument I am making, of a rough but survivable landing on Nutiran with a relatively intact airplane, to be reasonable, and supported by the observable facts, tires notwithstanding.  I just don't see the conditions as ideal or as anything one would attempt unless one's only other option was ditching at sea.

Joe Cerniglia
TIGHAR #3078C
Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 27, 2014, 09:23:13 PM

I find the narrow argument I am making, of a rough but survivable landing on Nutiran with a relatively intact airplane, to be reasonable, and supported by the observable facts, tires notwithstanding.  I just don't see the conditions as ideal or as anything one would attempt unless one's only other option was ditching at sea.

Joe Cerniglia
TIGHAR #3078C

Given that the video I saw said one thing and other sources say otherwise, I opted for proof by antithesis because often when I post the reactionaries get up all over me.

In this case I let the reactionaries do the work for me. The notebook refers to the Electra occupants suffering from personal injury and an heavy arrival remains a possible cause.

 

Title: Re: Earharts Radio Transmitter
Post by: Joe Cerniglia on July 28, 2014, 05:38:42 AM

I find the narrow argument I am making, of a rough but survivable landing on Nutiran with a relatively intact airplane, to be reasonable, and supported by the observable facts, tires notwithstanding.  I just don't see the conditions as ideal or as anything one would attempt unless one's only other option was ditching at sea.

Joe Cerniglia
TIGHAR #3078C

Given that the video I saw said one thing and other sources say otherwise, I opted for proof by antithesis because often when I post the reactionaries get up all over me.

In this case I let the reactionaries do the work for me. The notebook refers to the Electra occupants suffering from personal injury and an heavy arrival remains a possible cause.

I am persuaded we the reactionaries are not intending to be mean spirited but rather enjoy the give-and-take of a free-spirited debate.  To borrow an aphorism, they are as reactionary as the multiplication table.

Advancing as true a proposition one interiorly doubts is true in hopes others will disprove it (proof by antithesis) is a defensive and sometimes effective strategy. 

Asking it as a question might have engendered less confusion. 

I know from experience this is easily said and difficult in practice.

I played the reactionary with faith in your demonstrated talent for looking at things from multiple angles.  I hope you have not taken undue offense at the reaction.  None was intended.

Best wishes,

Joe Cerniglia
TIGHAR #3078C
Title: Re: Earharts Radio Transmitter
Post by: JNev on July 28, 2014, 05:49:30 AM
REACTIONARIES!?!  REACTIONARIES!!!

Not mean spirited?  Speak for yourself, Joe!!!

LOL!!!  ;D

Quote
In this case I let the reactionaries do the work for me. The notebook refers to the Electra occupants suffering from personal injury and an heavy arrival remains a possible cause.

That's an excellent application of synergy and synthesis, Tim!

Seriously, I don't know if we will ever know for certain whether those messages were the real deal or not, but if we can find the plane there maybe the evidence will bear these things out.  That would be a neat outcome in that more of the story might be known.

As to effects of landing on the reef, I've not been there, only seen pictures; if we've had a 747 captain on the ground there I'd have to bow to his judgment.  That said, those big tires on the Electra would have been very forgiving - but in all things there are limits.  Even short of damaging impacts, the plane could still have easily been bounced around enough there, IMO, to have knocked the occupants about quite a bit.  A head impact would not be hard to get out of that landing. 

In fact, there might have even been two unrelated events - the 'hard landing' might have merely been rocky, a bit lurching as the plane negotiated the uneven surface - enough to whack someone's noggin; a gear collapse / separation may have occurred after that fact by dropping the gear in a groove or something, then having the airplane weathercock from tidal forces, etc.

Lots of possibilities.  One hopes one day we'll see the first-hand evidence of what actually went.
Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 28, 2014, 06:42:03 AM
The Luke Field accident demonstrated that AE didn't need a rough surface to cause the gear to separate.









 
Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 28, 2014, 06:50:14 AM

In fact, there might have even been two unrelated events - the 'hard landing' might have merely been rocky, a bit lurching as the plane negotiated the uneven surface - enough to whack someone's noggin; a gear collapse / separation may have occurred after that fact by dropping the gear in a groove or something, then having the airplane weathercock from tidal forces, etc.

I like your reasoning. If only I could reassure myself that the port gear broke off, landing the port wingtip on the deck. That way the port wingtip would be something for the waves/water to be "2 feet over".

Now how to make that occur without yawing the nose to the sea?

Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 28, 2014, 06:51:55 AM

I played the reactionary with faith in your demonstrated talent for looking at things from multiple angles.  I hope you have not taken undue offense at the reaction.  None was intended.

Best wishes,

Joe Cerniglia
TIGHAR #3078C

Certainly no offence taken Joe. I appreciate you sharing your conversation with the veteran flyer.
Title: Re: Earharts Radio Transmitter
Post by: Tim Mellon on July 28, 2014, 06:52:58 AM
The Luke Field accident demonstrated that AE didn't need a rough surface to cause the gear to separate.


I might not draw the same conclusion: there is a big difference between taking off fully loaded (maybe even overloaded), on the one hand, and landing essentially empty on the reef, on the other hand. Her Luke accident was caused by poor control movements. And in Niku, no-one even knows if she or Noonan was performing the landing operation.

Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 28, 2014, 06:59:12 AM
I might not draw the same conclusion: there is a big difference between taking off fully loaded (maybe even overloaded), on the one hand, and landing essentially empty on the reef, on the other hand. Her Luke accident was caused by poor control movements. And in Niku, no-one even knows if she or Noonan was performing the landing operation.

Downunder we say "same set of clowns, different tent".

If the crew was the same and the plane was the same ...
you get my meaning.
Title: Re: Earharts Radio Transmitter
Post by: JNev on July 28, 2014, 08:59:42 AM

In fact, there might have even been two unrelated events - the 'hard landing' might have merely been rocky, a bit lurching as the plane negotiated the uneven surface - enough to whack someone's noggin; a gear collapse / separation may have occurred after that fact by dropping the gear in a groove or something, then having the airplane weathercock from tidal forces, etc.

I like your reasoning. If only I could reassure myself that the port gear broke off, landing the port wingtip on the deck. That way the port wingtip would be something for the waves/water to be "2 feet over".

Now how to make that occur without yawing the nose to the sea?

You don't have to convince yourself that it happened, just consider that it may have happened  ;)

"How" it happened might have a lot to do with where the nose wound up pointing.  For one thing, we might *assume* that she landed to the north such that a left leg loss would drag the nose toward the surf.  But suppose she landed in the opposite direction?

Also suppose for a moment that both legs remained intact until nearly at the end of the rollout, and the left leg then dropped into a groove at the last - with very little directional change.

Just thoughts.  So many possibilities.
Title: Re: Earharts Radio Transmitter
Post by: JNev on July 28, 2014, 09:07:44 AM
The Luke Field accident demonstrated that AE didn't need a rough surface to cause the gear to separate.


I might not draw the same conclusion: there is a big difference between taking off fully loaded (maybe even overloaded), on the one hand, and landing essentially empty on the reef, on the other hand. Her Luke accident was caused by poor control movements. And in Niku, no-one even knows if she or Noonan was performing the landing operation.

Very good points, Tim M.

She would have been at a relatively low-energy state on landing (low weight, low speed, low power), and the airplane should have been more easily managed and relatively forgiving on the reef's surface.

Conversely, heavy, high power and struggling a bit for directional control are demonstrably more hazardous in terms of flirting with loss of control than landing light.  Paul Mantz once expressed concern at AE's use of differential throttles on take-off to control yaw rather than raw rudder, which fits your observation I believe.  As pilots, we know what that peril can be, just as Mantz did: differential power is great for taxiing and parking, etc. - not so much during the more aero-dependant take-off scenario.  We don't have to be certain that she actually lost the bird that way at Luke Field - it isn't so hard to ground loop a heavy, high-energy state taildragger anyway.
Title: Re: Earharts Radio Transmitter
Post by: Martin X. Moleski, SJ on July 28, 2014, 10:04:57 AM
Downunder we say "same set of clowns, different tent".

In the Society, we say "Typical Affair Run by Ours" (TARBO).  It may be derived from a military command, of course.
Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 28, 2014, 11:12:04 AM

Also suppose for a moment that both legs remained intact until nearly at the end of the rollout, and the left leg then dropped into a groove at the last - with very little directional change.

Just thoughts.  So many possibilities.

At the end of one's argument, the starboard gear needs to be largely intact to permit the prop tip to clear the ground, to allow the engine to be started and run, to support the generator, to support the extended transmissions etc.

If the starboard gear was seaward on landing that places it closer to the water and dangers like the "nessie" trap.


Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on July 28, 2014, 11:19:57 AM

Conversely, heavy, high power and struggling a bit for directional control are demonstrably more hazardous in terms of flirting with loss of control than landing light.  Paul Mantz once expressed concern at AE's use of differential throttles on take-off to control yaw rather than raw rudder, which fits your observation I believe.  As pilots, we know what that peril can be, just as Mantz did: differential power is great for taxiing and parking, etc. - not so much during the more aero-dependant take-off scenario.  We don't have to be certain that she actually lost the bird that way at Luke Field - it isn't so hard to ground loop a heavy, high-energy state taildragger anyway.

My thoughts too.

With the centre of gravity behind the mains, it doesn't take too much to upset the directional control of a taildragger either during takeoff or landing.

My take is that AE, she had the only control wheel the other having been left on the ground in the Top End, dropped the Electra down with intent and at low speed because she anticipated a one chance arrival.

Title: Re: Earharts Radio Transmitter
Post by: Paul March on July 28, 2014, 12:53:38 PM

Downunder we say "same set of clowns, different tent".


As a former circus clown (seriously), that is absolutely hilarious. Further more, as a non-pilot, thank you to all participating on this topic for the vivid descriptions and explanations.
Title: Re: Earharts Radio Transmitter
Post by: Bruce W Badgrow on August 11, 2014, 02:37:42 PM
I have found a link to pages 302 to 307 of Aeronautical Radio by Myron F Eddy, published in 1939, that has info about Earhart's WE-13C transmitter. It is at www.aafradio.org/docs/Western_Electric_WE_13C (http://www.aafradio.org/docs/Western_Electric_WE_13C). Anyone interested in old WWII vintage military radios will like the www.aafradio.org  (http://www.aafradio.org)site. They have a lot of photos of the old equipment.

Bruce W Badgrow
Title: Re: Earharts Radio Transmitter
Post by: Tim Gard on September 22, 2014, 11:26:05 AM
Here's the video on which I based my statements  about the reef. (https://www.youtube.com/watch?v=l3SErNzHN2k)

Title: Re: Earharts Radio Transmitter
Post by: aafradio on November 25, 2014, 06:49:01 AM
I have found a link to pages 302 to 307 of Aeronautical Radio by Myron F Eddy, published in 1939, that has info about Earhart's WE-13C transmitter. It is at www.aafradio.org/docs/Western_Electric_WE_13C (http://www.aafradio.org/docs/Western_Electric_WE_13C).

That link should be www.aafradio.org/docs/Western_Electric_WE_13C_Transmitter.pdf (http://www.aafradio.org/docs/Western_Electric_WE_13C_Transmitter.pdf) in order to work properly.