Morse code key questions

Jump to: navigation, search

Two keys--both removed?

"Originally the airplane had two keys. One in the cockpit on the copilot's side and the other back at the navigator's station. Both keys were left behind. One was sent to Tinus and, as I recall, Gurr had the other one. Chater in Lae makes no mention of keys one way or the other." [1]

In terms of saving weight, the removal of the two keys makes sense. Once the crew was trimmed from four (Earhart, Manning, Mantz, and Noonan) to two (Earhart and Noonan), having a key at the navigator's station was superfluous. Since neither Earhart nor Noonan were proficient in sending Morse Code[2] and intend to rely on voice communication, there was no need to carry the key in the cockpit, either.

"The WE13C transmitter came from the factory with a provision for three crystal-controlled frequencies. Prior to the first World Flight attempt Earhart's transmitter was set up with crystals for 3105 kcs, 6210 kcs, and 500 kcs. It is true that 500 kcs was useful only for code and required a trailing wire antenna for effective propagation but for the first World Flight attempt the aircraft carried a navigator/radio operator (Harry Manning) who was adept at code and the Electra was equipped with a trailing wire antenna. Both Manning and the trailing wire were absent for the second World flight attempt. Gurr had lengthened the dorsal vee antenna in an attempt to provide a modicum of capability on 500 kcs but all he really accomplished was screwing up 310 5 and 6210. There was no reason for Earhart to carry a morse-sending key on the second attempt. She had no real capability on 500 kcs and neither she nor Noonan could send or read morse anyway."[3]

Ric Gillespie, 5 Sep 2000[4]

Evidence that Gurr had one key

Goerner: "It has been alleged that AE left the CW key in Miami and that neither she or Noonan could send CW. Did the Earhart plane have a CW capability either through CW key or through depressing the voice phone, and what do you remember about the CW capabilities of Earhart and Noonan?"

Gurr: "Equipment had CW capability. Key, was taken off after Capt. Manning left, as [neither] Amelia nor Noonan knew enough code. I still have the key if you want it?"[5]

Evidence that Tinus had the other key

In Amelia My Courageous Sister Carol Osborne reproduces the text of a 1962 letter from W.C. Tinus, Vice President of Bell Telephone Laboratories:

I was the radio engineer who was responsible for the design and installation of her radio communications equipment [at the Newark Airport, New Jersey in February, 1937] and since there is apparently still some doubt as to what her equipment consisted of, perhaps I can clear up one or two points ...
I had been a radio operator aboard ship in my younger days and knew the importance of being able to communicate at 500 kc [kHz] over the oceans. I persuaded Miss Earhart and Mr. Putnam on this point and modified a standard three-channel Western Electric equipment of the type then being used by the airlines to provide one channel at 500 kc and the other two at around 3000 and 6000 kc [3105 and 6210 kHz] ... A simple modification also enabled transmission to be made on CW or MCW, as well as voice, and a telegraph key was provided which could be plugged in, in addition to a microphone for voice communication. It was my thought that many ships throughout the world had 500 kc radio compasses and could probably better obtain bearings if the key were held down for an extended period while radiating modulated CW (MCW).
I was less successful in persuading Miss Earhart of the importance of having a qualified radio operator in her crew. I had only a short period one afternoon at Newark Airport to show her and captain Manning (of the United States Lines Sea Rescue fame) how to operate the equipment.
... I did not see her equipment during the period between the first and second starts, but had no reason at the time to believe it had been changed.
Several months after her disappearance we received a small package from Pan American Airways at Miami containing her telegraph key, cord and plug, which she had left in their hangar there. Without these items she could have communicated on 500 kc by voice and could have sent out a suitable signal for direction finding by simply holding the microphone button down for a time. The remainder of her equipment peculiar to the low frequency 500 kc channel probably weighted five or ten pounds, but apparently she did not leave it in Miami or it, too, would have been returned to us.

He ended:

... She was equipped for 500 kc communication originally and she did leave one item, her telegraph key, behind when she departed from Miami.

Objection: switch necessary for voice transmission?

Mike Everette, 5 September 2000[6]

After I made my posting last night I took another look at the WE-13C transmitter schematic... something I said last night wasn’t quite right. I stated that it would have been no problem for AE to leave the telegraph key behind if all she wanted was voice transmission; just unplug it and remove it from the cockpit.

Well... that’s not right.

Indeed, it is not possible.

The "key" in this setup was more than just a morse key. It was part of a subassembly, a control unit. The unit contained the key and a switch. The switch, a double-pole double throw type, had two positions, labeled "CW" and "PHONE." Like I said last night, throwing the switch to "CW" closed the push-to-talk line (like the mic switch would do on voice) and made the rig READY to transmit. The "keying" was through an added relay. This relay actually followed the operator’s key.

To RECEIVE on CW, it was necessary to throw the switch on the controller containing the key BACK to "PHONE." Potentially confusing.

I had forgotten one more important function of that switching circuit, last night.

That switch, when thrown to "PHONE," also closed the CW keying relay circuit. The keying relay, therefore, was energized continuously when the rig was switched to "PHONE."

That way, the radio was ready to transmit on voice. It was NOT "keyed" on voice until the mic switch grounded the PTT circuit, energizing the dynamotor starter (and therefore applying high voltage) and antenna relays. The CW keying relay had to be closed to enable the tubes to function, by grounding the blocking-bias that kept them from drawing current (as well as applying screen grid voltage to the multiplier and final amplifier stages).

To summarize: Since the transmitter operated in Push to Talk fashion (PTT) on voice, the CW keying relay had to be closed on voice. It did not operate with the PTT circuit. The ’CW-PHONE" switch closed this relay on voice. The key closed it on CW, AFTER the "CW-PHONE" switch was thrown to CW mode. The switch had to be returned to "PHONE" to RECEIVE ON CW, in order to de-energize the antenna relay and dynamotor.

The transmitter DID NOT operate in "break-in" style on CW (the equivalent to push-to-talk operation on voice).

But here is a thought, and an important one:

If TWO ANTENNAS were used (one transmit, one receive) it would not have been necessary to have the antenna relay de-energized in order to receive; so returning the switch to "PHONE" would not have been a requirement.

The bottom line:


UNLESS, and we may never be able to completely resolve this... some sort of modifications were made to the radio in Miami, to bypass this switch. All it would have taken, was a "dummy" connector plugged into the transmitter where the key unit was connected... if Pin 4 of this connector was jumpered to ground, that would complete the keying relay circuit. Of course, an internal mod to the transmitter’s wiring could have accomplished the same thing.

How hard is the evidence that she left the key behind? Anecdotal? It may be worth the paper it is printed on.

We have been through this before... wonder if there are any scraps of paper anywhere detailing the work done on that radio in Miami? Did Pan Am techs do it? Anybody search the Pan Am files that closely? (Chances are none to slim, right? Probably the document retention schedule was not that long and any such paper was tossed out with other routine stuff....)

A lingering question from earlier postings by others:

Would it have been possible to "key" this radio on CW, using the mic button?

Yes. BUT... It would have produced a very ragged, awful signal. The keying speed would be very slow. And the radio would have been damaged quickly because of heavy current circuits being made and broken, which were never intended to be so operated.

Subject: The Key Date: 9/7/00 From: Mike Everette


I had forgotten the Gurr connection with the telegraph key. It’s been a while since I last read over his letter to Goerner.

Joe Gurr could have very easily made the necessary mods to the radio to jumper the switch function and therefore keep the radio in "Phone" mode. But! Here is a reason why he would NOT have done so, and one that raises credibility issues.

Gurr was trying to "help" AE (yeah, right)preserve her transmitting capability on 500 KHz, by reconfiguring the dorsal antenna to serve on 500 instead of using the much more efficient trailing wire. AE apparently wanted the trailing wire removed, and radio operation simplified, after Harry Manning bolted from the second flight attempt... Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section).

So, AE knew (we believe) that she needed to preserve the 500 KHz capability. In those days, 500, or "600-meters" (wave length) was the only emergency universally guarded by ships.... and she would be over water quite a bit.

NOBODY used voice on 500! It was then, and continued so until the mid 90s when the regulation requiring ships to guard it was phased out, a CW frequency only. Even Joe Gurr would have known this. He would have come on very strong to AE, I think, about this and the necessity for keeping her CW key.

No one monitoring 500 would have been listening for/expecting a voice signal on 500.

HOWEVER, was AE so strongheaded that she disdained all Gurr’s (and others) expert advice? Could have been. Very likely. ("I don’t care...")

If Joe Gurr had that key I for one would like to know what happened to it. What happened to Gurr’s estate? Did he have heirs? Or was the contents of his house trashed, like I saw happen to the stuff of a recently deceased old time Ham in Durham, NC last month? Wonder if that key has ever turned up at a Hamfest someplace? Wonder if the person who has it now is aware of its origin and significance (and value)?


  1. Ric Gillespie, 30 Jun 2004 Forum.
  2. Chater Report
  3. Ric Gillespie, 9 September 2000 Forum.
  4. Forum.
  5. "Questions from Goerner, answers from Gurr."
  6. Forum.