Goerner interviews radio expert Joe Gurr, Part II

We continue today with Part II “What Radios Did She Really Have?” our retrospective look at the Amelia Earhart Electra’s radio capabilities via interviews of radio expert Joseph Gurr by Fred Goerner as compiled by researcher Cam Warren.

In answer to Fred’s query as to how Amelia got this “Navy gear.”  Gurr replied: “I asked no questions.”  Fred showed him several photos of the plane “passed by Navy censors.”  They clearly showed the topside antenna mast and the loop, “and some of the gear below.”  Gurr confirmed that this showed the configuration after the rebuild.

Fred: “Right after the disappearance, newspaper accounts ’mentioned a Joseph Gurr, Burbank engineer, who installed the sending apparatus.’ Then [the story] quoted you as having said: ’9.3, 15.5 and 21.7 mc.’  What does that mean to you?”

Gurr: “She could receive [those] frequencies on the Bendix gear, but not transmit on [them].”

Fred: “To get a heading from the Bendix Direction Finder?  She would receive on those frequencies?”

Gurr agreed, saying: “This was high frequency.  It also had the [2-400 kc band]. [I’m afraid I didn’t stress to Earhart] the value and usefulness and that gear.  Oh, it was wonderful!”

The Bendix RA-1B, used in Amelia Earhart’s Electra during her final flight without apparent success, was a brand-new product and was reputed to be pushing the state of the art in aircraft receiver design.

Fred asked if Gurr thought Fred and Amelia knew how to operate it property.  The reply was only a grunt.

[There following a discussion of the gasoline load, then the subject returns to radio].

Fred: “Why was it do you suppose that Amelia never broadcast on 500 kc? All during the flight on which she disappeared, she never once broadcast on 500 kc.  The Itasca had a 500 direction finder.  The Navy had sent a 3105 direction finder down from Pearl Harbor and installed it at Howland Island.  She kept broadcasting on 3105 and asked the Itasca to take a direction on her on 3105. The Itasca kept asking her to broadcast on 500 and she never did on 500.  Why not?”

Gurr: “There might be a number of reasons for that.  At 500, I never was able to work anybody on 500 when I was working on the equipment.  That was only here locally.  500 kc is a very, very low frequency and you have to have power to get out at all.  [She had] her little 50-watt transmitter and a reduced size antenna.  On 500 kc you want to have a proper antenna.   On sea-going ships, they have these great big antennas between the masts that are separated by quite a distance and they have a lot of wire out there.  That is what you have to have.  On an airplane where she did not have much of an antenna, her range on 500 kc was very short.  If she was, let’s say in sight of a ship, she could talk.  As I recall, we talked about that very thing.  If she was in an overcast and she raised a ship, she could be sure the ship was not very far away.  In reading your book, I think you explained it very well.  She did not stay on the air long enough for the Itasca to take a beating on her.  In those days we didn’t have the automatic features.  We had to do all of this manually.  The radio operator on the Itasca would tune the signal in, then he had to rotate his beam to get a null and I don’t think she ever talked long enough for him to do that.  They kept asking her to send ’A’s.  All they needed was that carrier.”

Fred: “She asked the Itasca to send ’A’s on 7500.”

Gurr: “That means she was using that Bendix machinery.  On 7500 she could have heard that if the Itasca had any power at all, even 2[00] or 300 watts.  They could transmit a good signal for several hundred miles.”

Fred: “At one point, she said, ’we are receiving your signals but cannot get a minimum.’  What did that mean?“

Gurr: “That means she was turning the loop and could not get a null.”

Fred: “Because of what? The signal was too weak?”

Amelia, with Bendix Corporation rep Cyril Remmlein, and the infamous direction finding loop that replaced Fred Hooven’s “radio compass” or “automatic direction finder.”  Hooven was convinced that the change was responsible for Amelia’s failure to find Howland Island, and ultimately, for her tragic death on Saipan.  Whether the loop itself failed the doomed fliers during their final flight remains uncertain.  See p. 56 Truth at Last for more.  (Photo courtesy Albert Bresnik, taken from Laurance Safford’s Earhart’s Flight Into Yesterday.)

Gurr: “There are many reasons she could not get a null.  As an example, unless you have a considerable number, a quite strong signal, nulls are not easy to find.  If the signal is weak, you can go through a null.  You have to have a solid signal.  Then too, in those days the equipment wasn’t developed like it is these days.  State of the Art is quite different.

“In those days, a little static — maybe she was excited, flying the airplane and trying to tune the set to get the best signal.  She might have had the loop turned more or less at the null.  She should have had it straight forward, if she was headed toward Howland.  Had the loop fore and aft to get the maximum signal.  She had a sensing antenna which was that V-antenna and the idea was to first tune in the signal on that antenna and then switch it over to the loop and get a bearing.”

Fred: “This takes time.”

Gurr: “And it takes a certain amount of cool-headedness about that time.”

Fred: “The trailing antenna had been removed at that time?”

Gurr: “It was still on board.  She did not use it on 500 kc.  That was the object of the antenna on top.  We put on all the wire we could, as much wire up there as possible, and to get it off the fuselage so that the fuselage would not have an absorbing or a reflecting effect.  We were very successful.  Actually she had as much wire as possible on that airplane.  This was for transmitting.  For receiving, you didn’t have to have that much.  She had that V-antenna down there which was fine.”

Fred:  “Apparently that was working very well because she checked back in with Lae, New Guinea 800 miles out on 6210 in the daytime.”

Fred: “There were messages that amateur radio operators said they had received after the time of the disappearance of the plane. They were received along the Pacific Coast.  I have talked to a number of the operators and I believe they actually did receive messages. Would it have been possible to broadcast if they had been down in the water?”

Gurr: “Yes.  The antenna was dear.  If that airplane was floating, the antenna was up on top of the fuselage and she could transmit until that antenna was submerged.”

Fred: “Did she have batteries in the cockpit or something that would enable her to power her gear.”

Gurr: “Storage batteries, yeah. There was a storage battery generator. In flight, the generator was charging the batteries. In those days, airplanes carried decent flight batteries. I don’t remember how many she had, but I know she had at least one.  Flying along as she was, that battery was probably well charged.  Then, supposing she was down in the water, and got on the air to transmit, she had the power.  The transmitter itself did not take an awful lot of juice.  It was a low powered transmitter.  She could probably transmit for 30 minutes if the battery was fully charged.  Intermittent, maybe longer than that.”

Fred: “Could 3105 be received on the Pacific Coast and not be received in the general area of where she went down?”

West Coast amateur radio operators Walter McMenamy (left) and Carl Pierson, circa 1937, claimed they heard radio signals sent by Amelia Earhart, including two SOS calls followed by Earhart’s KHAQQ call letters.

Gurr: “Oh yes.  Especially at night. 3105 at night.  It was daytime between here and Howland Island.  It is very unlikely, but at night, yes.  These frequencies are subject to a certain amount of skip and the higher frequency you go, the more that skip.”

Fred: “And not be received by a vessel in the general area?”

Gurr: “That’s right.”

Fred: “This Navy direction finder, the 3105 that the Navy Dept. sent down on board Itasca to use in conjunction with the flight evidently was a rather hush-hush model at that time.  They were experimenting with high frequencies, through a department and the Navy known as OP-G20, which was Naval Intelligence Communications.  You know anything about development of high frequency direction finders at that time?”

Gurr: “Only things that were published.  I had no connection with the Navy or any military organization so far as any of the classified developments.  We knew in the airline business and especially being interested in radio as I was then, I knew pretty well what developments were upcoming.  We knew the limitations of the low frequencies.  We knew that we had to have something better.  Obviously the experimentation had to go to the high frequencies.  At that time there was a feeling that the high frequencies had a tendency to bend, the waves would bend and would get a false radio direction finding.  Maybe that was true in certain locations, certain altitudes and so on.  This was all subject to experimentation.  That was brand new stuff in those days. Now, as you know and we know, the military is always researching, developing and working on projects.  Now-a-days, they call it classified, or secret.  You never stop.

“Obviously the Navy had classified gear then.  And they have it now.  The 3105 [kc] radio
direction finder was considered a pretty high frequency to get a reliable direction, at that time. Today, we know its limitations.  We know what it is doing.  The airlines now have fully automatic units that lock on to the beam and take it right down the line.  In those days, we thought 3105 was getting into rather high frequency.”

(End of Part II.)