Amelia Earhart's Transmission from the Pacific - UPDATE

[prcguy]

I had access to a remote rig (TenTec Onmi VII) about 10mi south of Pearl Harbor, but the rig is here in CA for some maintenance and upgrades and we can't get it back on the island for a couple of months. That would have been one of the best spots to hear these transmissions.
prcguy

Neither 6210 KHz (which is on the outer edges of the 49m broadcast band) nor 3105 KHz (which I think is reserved for aero off route) are within the amateur service.

For places where 49mb is still dark, you might have issues with a few international broadcasters that wander up that far (even tho they're not supposed to...).

Would be more interesting if we could do this without having to resort to a remote receiver, but for us Easterners, that's the only shot - if a long one - we would have.

Mike

 

[prc117f]

Even if you did have a Amateur Radio license, those frequencies (3105 and/or 6210 kilocycles) are not legal amateur frequencies. However, it is possible for you to request a limited use license from the FCC. We do it regularly on the VHF/UHF and microwave bands so they might allow it on the HF bands.

And, as "jbantennaman" said, you can use any transmitter that runs 50 watts AM. It's all pretty much the same. If you put the signal from the Model 13c up against a newer transmitter, running the same power (50W) and mode (AM), you would have a hard time telling the difference. Except that, the newer transmitter might have cleaner audio.

But you haven't mentioned what you are using to receive the signal. Receivers have come a long way from the 30s and 40s. They are far more sensitive and selective these days.

Are you also looking at propagation? Propagation will have a lot to do with whether your signal will get through. And if it gets through, how well it is heard. The two frequencies you mentioned (3105 and/or 6210 kilocycles) are primarily night time frequencies, for long distance communication. During the day, propagation may only be a few hundred miles.

Martin - K7MEM

I think those frequencies are open as Echo Charlie frequencies. he would just need to join a EC DX Club get an EC callsign

 

[k9wkj]

does the FCC have anything to do with a land based call from Howland ?

 

[Token]

I think those frequencies are open as Echo Charlie frequencies. he would just need to join a EC DX Club get an EC callsign

Those frequencies, 3105 and 6210 kHz, are not really “open” in any way, certainly not as “Echo Charlie” freqs. Echo Charlie is simply a group of what used to be called pirate radio operators. Today pirate carries more of a music based transmission connotation, but regardless, they are still illegal and unlicensed operators illegally transmitting. As such I guess that makes every frequency an EC freq, although traditionally EC has stayed pretty close to 6670 kHz.

No need to join a club to make an illegal transmission, and EC callsigns give the holder no legal status or rights to any specific frequency.

3105 khz would be in the aeronautical mobile allocation, and 6210 kHz would be in the maritime allocation. 6210 kHz would be between duplex channel 604 (6209 kHz) and 605 (6212 kHz) ship side transmit freqs, and an AM transmission on 6210 kHz would cause interference to both of those frequencies.

T!

 

[majoco]

I think that the radios and frequencies that Earhart used were not 'official' . There weren't any HF aircraft radio stations in those days and she was loaned the transmitter/receiver and had people with equipment at intended landing places along the route to take messages - there may not have been a transmitter at the ground site. Long distance reception possibly wasn't needed or expected. It was maybe just a fluke that her transmissions from the Marshall Island or wherever were received in the US.

 

[Token]

I think that the radios and frequencies that Earhart used were not 'official' . There weren't any HF aircraft radio stations in those days and she was loaned the transmitter/receiver and had people with equipment at intended landing places along the route to take messages - there may not have been a transmitter at the ground site. Long distance reception possibly wasn't needed or expected.

The ITU, or its predecessor, was established in 1909. It became very apparent after the Titanic disaster in 1912 that coordination in radio was needed, so maritime radio became more structured.

When aviation took off the lessons learned in the maritime communications realm were applied to aviation, and people attempted to establish protocols, frequency bands, and expectations. The Regulation of Aerial Navigation was signed in Paris in late 1919. The Habana Convention on Commercial Aviation in 1928 included specific guides and goals to aerial navigation and communications development. Conventions and regulations continued to be adapted and improved over time, and by the early 1930’s there were many organizing and regulating bodies, both international and national.

In other words, although I can find no hard data, it is quite likely that the freqs used by Earhart at the time were “official”, as in regularly used aviation or combined aviation/maritime bands. Remember that the Coast Guard vessels supporting her flight were on those same freqs, and expected to communicate with her there.

Of course a lot has changed since then, and what may have been aviation or shared use freqs at that time are now allocated for other services. Note that one of her used frequencies, 3105 kHz, is still in an allocation for aeronautical mobile use.

It was maybe just a fluke that her transmissions from the Marshall Island or wherever were received in the US.

None of the reported receptions in the US have ever been confirmed. I think it quite likely that most, if not all, were either mistakes or out and out lies. It seems a bit far fetched to me that a woman with a console radio and no external antenna managed to hear a signal that no official or professional monitor heard, and yes, the official/professional monitors were specifically attempting to hear such.

T!

 

[WA8ZTZ]

Looks like the path from the Marshall Islands to Hawaii will initially be in darkness. To the west, the path to VK/ZL land will be nighttime.

Seems like a long way to go just to transmit for a grand total of 24 minutes spread over 2 days but nonetheless good luck to the OP.

btw... IIRC,back in the days of the LF radio range stations (200-400 kc), some stations had the ability to transmit AM voice. The aircraft would reply AM voice on the frequency range 2400-6500 kc.

 

[wb6uqa]

5.8 MHZ - 6.2 MHZ

This is the Tropical shortwave band. Many USA and Cuban stations. If you hear them you have a chance. For 50 watts I use a Harvey Wells Bandmaster.

 

[ka3jjz]

Actually that band is more considered to be an international broadcast band (49 meters) than a tropical one, although it is true you can find several tropical band broadcasters here as well (Brazil used to be a big player here)...and there are many international broadcasters here, too, not just US and R Havana...

Please let's not get off topic about discussing out of band broadcasting, clubs, and so on. Let's stick to the topic of the historic broadcast and leave those discussions for elsewhere...Mike

 

[majoco]

Looks like the path from the Marshall Islands to Hawaii will initially be in darkness.

I don't know where you got this info from, according to "DX Atlas", Majuro is well into daylight at 1930UTC on Dec 15th.

 

[Token]

I don't know where you got this info from, according to "DX Atlas", Majuro is well into daylight at 1930UTC on Dec 15th.

Two hours earlier. 1230 EST and 1300 EST, the times quoted for transmission, are 1730 UTC and 1800 UTC. It think that will make it just about sunrise local time, but still a daytime path into the US.

Regardless, I have several SDRs on various antennas programmed to try to catch and record these transmissions. While it is extremely unlikely I will hear them, a person still has to try. If the transmissions were a couple hours earlier, say 1430 or 1530 UTC, the chances would be much better. At that time I still typically have good coverage into the south Pacific, often with Australian and Pacific Island stations well heard. Several lower power PNG stations are on my regular list to check as a propagation indicator.

T!

 

[majoco]

Apologies, I used the earlier posting where the transmission times were 1400EST - even so, I was still half and hour out!.

 

[WA8ZTZ]

Initially, looks like path from Marshall Islands to Hawaiian Islands mostly greyline. VK still in darkness.
Ooops... was wrong about ZL, daylight there, sorry.

 

[ka3jjz]

Just by way of a brief and general explanation, for those that are not familiar with how HF works, both the 3 and 6 Mhz frequencies would need a darkness path to have a chance to reach the States. During the day the ionosphere won't propagate these frequencies for more than a couple hundred miles (if that).

However there evidently is a slight chance that people using a remotely-controlled receiver might hear it. There are many such receivers scattered world-wide; some utilizing SDRs.

The discussions below are because of that fact. Carry on, folks...Mike

 

[WA8ZTZ]

On nearby frequencies all that was heard was CFRX 6070 Toronto with a clear 1 kw signal and CHU 3330 Ottawa with a loud 3 kw signal. WWV 5000 was readable but noisy.

FWIW, K index was 0 but SFI was only about 70 but these numbers probably don't mean too much given the daytime D layer absorption at the desired frequencies.

 

[Token]

I recorded the freqs during both time periods today, one SDR on a Rhombic pointed 270 (Australia bearing from my location in the Mojave Desert) the other SDR on a DB36 tuned as low as it will go and pointed that way. Nothing heard on 6210 kHz, although there was a very weak carrier that came up on 6212 kHz about the right time.

T!

 

[db_gain]

I listened in on the third harmonic of the 6MHz freq and heard/saw nothing.

 

[lgkinney]

I just returned from the Marshalls. I was able to check a few emails while waiting for my flight from Honolulu. So far no one has heard our message. We strung the antenna wire on the island no more than twelve feet high running north and south because that would have been the height of Earhart's V antenna on the top of her fuselage. We used a 50 watt transmitter that more than likely put out slightly less than 50 watts. We moved our boat two miles away. Our radio man on the boat picked us up clearly on both 3105 and 6210 Khz.

In an email, one person thought he picked up a carrier wave on one of the two frequencies at the time we transmitted. Another thought he heard some intermittent Morse code. We did click on the mike several times prior to our transmissions but it was not in CW telegraphy.

Following each 30 second transmission we asked for anyone hearing us to transmit back. Several times it appeared we heard an attempted response Several times we saw the meter swing over and heard static but not an audible response.

Unfortunately, we were not able to transmit on the second scheduled day. A big storm came in and of course we were in the open on that island. We had to get our equipment back out to the boat. We did pick up transmissions from Asia and a US radio station that came in loud and clear probably on harmonics. Please pass this message report on to all your friends that attempted to assist us.

Thanks again, to all of you that participated in our little experiment.

Les Kinney

 

[WA8ZTZ]

Interesting experiment but several 30 second low power AM transmissions would be hard to intercept even under ideal conditions... and conditions were not ideal as most everywhere east of the Marshalls was in daylight.

 

[prcguy]

Maybe this finally explains why Ms Earhart was never found.
prcguy

Interesting experiment but several 30 second low power AM transmissions would be hard to be intercept even under ideal conditions... and conditions were not ideal as most everywhere east of the Marshalls was in daylight.