Advanced search  
Pages: 1 [2] 3   Go Down

Author Topic: Electra radio equipment and antennas  (Read 27938 times)

Martin X. Moleski, SJ

  • Administrator
  • *
  • Posts: 2882
Re: Electra radio equipment and antennas
« Reply #15 on: September 06, 2013, 06:24:10 PM »

I have not been able to find a discussion of the skip problem with 6210 kilocycle transmissions. Could you point me in the right direction?

There are a few thoughts and links in the article on "Radio propagation."

LTM,

           Marty
           TIGHAR #2359A
 
Logged

Gary L Kerr

  • T1
  • *
  • Posts: 8
Re: Electra radio equipment and antennas
« Reply #16 on: September 14, 2013, 05:17:39 PM »

Ken brought up a very interesting point in 2010:

Considering that 1937 was about the height of that solar cycle for radio propagation and that the transmitter was right adjacent to salt water (a great reflector), it's certainly possible that these signals were heard in the US and elsewhere.

You can see a graph of past solar cycles here.  Look for the "Monthly  Sunspot Numbers 1900-1999" graph.  The higher the sunspot number, the better for radio wave propagation.  http://www.wm7d.net/hamradio/solar/historical.shtml
Gary
TIGHAR #4305R
 
Logged

Doug Ledlie

  • T2
  • **
  • Posts: 78
Re: Electra radio equipment and antennas
« Reply #17 on: May 12, 2014, 08:53:40 PM »

Another hibernating thread resurrected...

Have been trying to educate myself regarding Vee antennas and have found some discussion around the web that they can be significantly "directional" in certain configurations ie significantly better performance opposite the vertex.

Some talk confirming directional characteristics of the Electra dorsal vee here:
http://tighar.org/wiki/Dorsal_antenna#cite_note-6
but I didn't find anything more in depth.

So, any radio experts know if the electra vee antenna directionality could be estimated with any accuracy.
Logged

Tim Gard

  • TIGHAR member
  • *
  • Posts: 161
Re: Electra radio equipment and antennas
« Reply #18 on: May 12, 2014, 09:34:04 PM »

Another hibernating thread resurrected...

Have been trying to educate myself regarding Vee antennas and have found some discussion around the web that they can be significantly "directional" in certain configurations ie significantly better performance opposite the vertex.

Some talk confirming directional characteristics of the Electra dorsal vee here:
http://tighar.org/wiki/Dorsal_antenna#cite_note-6
but I didn't find anything more in depth.

So, any radio experts know if the electra vee antenna directionality could be estimated with any accuracy.

I found this to be very rewarding ...

https://www.youtube.com/watch?v=IqS9GXM7nag

The videos are a very quick way of grasping the hypothesis details ...

https://www.youtube.com/user/TIGHARchannel

Click on the word "videos" next to home to have the full list displayed.
/ Member #4122 /
/Hold the Heading/
 
« Last Edit: May 12, 2014, 10:00:40 PM by Tim Gard »
Logged

Doug Ledlie

  • T2
  • **
  • Posts: 78
Re: Electra radio equipment and antennas
« Reply #19 on: May 13, 2014, 05:54:03 AM »

Thanks Tim, good info

I had seen some discussion before about signal "donuts" (mmmm...now I'm going to be drooling on my shirt all morning)

Was wondering though specifically about pure transmit directionality possibilities ie maybe the Electra configuration provided 2 watts ahead, 1 watt sideways and 20 watts behind or 20 watts ahead and 2 watts behind etc - those are totally random numbers btw not suggesting those are the actual numbers or even proper terminology.

Ultimately wondering how the antenna being on a different plane (thats plane in the vertical/horizontal sense) when parked vs in flight, 10E being a tail dragger, would impact transmission possibilities.  Haven't found that point discussed and maybe its irrelevant, dunno
« Last Edit: May 15, 2014, 05:48:22 AM by Doug Ledlie »
Logged

Tim Gard

  • TIGHAR member
  • *
  • Posts: 161
Re: Electra radio equipment and antennas
« Reply #20 on: May 17, 2014, 02:13:05 AM »

Was wondering though specifically about pure transmit directionality possibilities ie maybe the Electra configuration provided 2 watts ahead, 1 watt sideways and 20 watts behind or 20 watts ahead and 2 watts behind etc - those are totally random numbers btw not suggesting those are the actual numbers or even proper terminology.

I've forgotten where I acquired the info, but somebody modified Amelia's antenna, if not her ATU, to try to improve support for a wider range of frequencies.

The result was not as successful as planned and I think 6210 KHZ suffered by the mod.

/ Member #4122 /
/Hold the Heading/
 
Logged

Martin X. Moleski, SJ

  • Administrator
  • *
  • Posts: 2882
Re: Electra radio equipment and antennas
« Reply #21 on: May 17, 2014, 05:18:59 AM »

... somebody modified Amelia's antenna, if not her ATU, to try to improve support for a wider range of frequencies.

The result was not as successful as planned and I think 6210 KHZ suffered by the mod.

"NR16020 antennas."
LTM,

           Marty
           TIGHAR #2359A
 
« Last Edit: May 17, 2014, 07:21:50 AM by Bruce Thomas »
Logged

Tim Gard

  • TIGHAR member
  • *
  • Posts: 161
/ Member #4122 /
/Hold the Heading/
 
Logged

Neff Jacobs

  • T2
  • **
  • Posts: 54
Re: Electra radio equipment and antennas
« Reply #23 on: March 02, 2015, 05:20:44 PM »

I ran across an article from the December 1942 Electronics Magazine by  Paul Holmes Chief Engineer of Stoddart Aircraft Radio Company.

According to Holmes the practical length of an Off Center Fed V includes the length of the fed line and from the feed point to the long end of the V.  Holmes ignores the short end of the V  Each leg scales 25.4 feet long on the Long illustration of the L10.   The feed point appears to be at 5.25 feet from center as does the length of the feeder as applied at Miami.  It comes to 35.5 feet.  If the wire was in free space it would resonate at 6931kc.   According to Holmes Nomograph  featured in the article more like 6200kc.   6210 would be a good guess.   The nice thing about the off center fed V is you can change it's resonate frequency by changing  the feed point.   A Mininec model of the antenna appears to be a short top loaded vertical.   Most of the radiation is vertically polarized.  The V acts much more as a capacity hat and does not radiate to a significant degree.
Neff
Logged

Eddie Rose

  • T1
  • *
  • Posts: 19
Re: Electra radio equipment and antennas
« Reply #24 on: March 05, 2015, 02:41:46 PM »

Before the last flight, how many times in her flying career had Amelia used the radio direction finder unit successfully to find a destination?
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5183
  • "Do not try. Do or do not. There is no try" Yoda
Re: Electra radio equipment and antennas
« Reply #25 on: March 05, 2015, 03:04:56 PM »

Before the last flight, how many times in her flying career had Amelia used the radio direction finder unit successfully to find a destination?

Never.  Even the test she did at Lae the day before she left for Howland failed.
Logged

Martin X. Moleski, SJ

  • Administrator
  • *
  • Posts: 2882
Re: Electra radio equipment and antennas
« Reply #26 on: March 05, 2015, 03:13:17 PM »

Before the last flight, how many times in her flying career had Amelia used the radio direction finder unit successfully to find a destination?

I'm going to put my money on "zero."

It's hard to prove a negative (not impossible, just difficult).

I'm emphasizing "Amelia" in your question.

If RDF was used in the first leg of the first round-the-world attempt, as seems likely to me, it wasn't Amelia at the controls; Mantz and Manning took seven bearings

Of course, we don't have complete records of every flight AE took in the Electra after the cockpit was re-configured to put her in charge of RDF.  So the correct answer might be greater than zero.  But in such test flights, I imagine they had other means of getting back home.  My impression is that the first time she was dependent on RDF to "find a destination" was on the flight from Lae to Howland.
LTM,

           Marty
           TIGHAR #2359A
 
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5183
  • "Do not try. Do or do not. There is no try" Yoda
Re: Electra radio equipment and antennas
« Reply #27 on: March 05, 2015, 04:50:31 PM »

Of course, we don't have complete records of every flight AE took in the Electra after the cockpit was re-configured to put her in charge of RDF.

How was the cockpit re-configured?
Logged

Martin X. Moleski, SJ

  • Administrator
  • *
  • Posts: 2882
Re: Electra radio equipment and antennas
« Reply #28 on: March 05, 2015, 05:03:49 PM »

Of course, we don't have complete records of every flight AE took in the Electra after the cockpit was re-configured to put her in charge of RDF.

How was the cockpit re-configured?

OK.  I must have gotten confused with the removal of the Hooven control head, for which there are TIGHAR documents, and the location of the remote control heads for the transmitter and receiver:

Michael Everette, "Technical Analysis"

"Channel shifting was accomplished by means of a multi-gang switch to select crystals and tuned circuits for each channel. The switch was activated from a crank on a remote control head located in the cockpit, linked to the transmitter through a flexible tach-shaft resembling an automotive speedometer cable."

"The Model 20B receiver was a remote-control model, with tuning dial, band switch, volume control and other controls located in a Model 27A remote control head linked to the receiver by means of tach-shafts. The remote head was mounted in a center console below the instrument panel in NR16020; the receiver itself was mounted beneath the right seat in the cockpit."

I thought that some of these controls were at the navigator's station and then were moved to the cockpit after the first attempt.  The transmitter was below the navigator's table (Ric Gillespie, 2 March 2009 Forum.)

OK, took a while, but I found the info I've been looking for.  It's in a post from Ric Gillespie, 20 November 2014, Forum. I had thought that the frequency control switches were over on AE's side of the cockpit, but manifestly, that is not the case.


LTM,

           Marty
           TIGHAR #2359A
 
« Last Edit: March 05, 2015, 05:53:55 PM by Martin X. Moleski, SJ »
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5183
  • "Do not try. Do or do not. There is no try" Yoda
Re: Electra radio equipment and antennas
« Reply #29 on: March 05, 2015, 05:23:44 PM »

The controls for the radio were moved to her side of the cockpit, I believe. 

I think my source is Ric Gillespie.

You KNOW you can't trust that guy.
As far as I know, we don't have a photo of the cockpit layout after Manning jumped ship and the plane was repaired following the Luke Field wreck.
Logged
Pages: 1 [2] 3   Go Up
 

Copyright 2018 by TIGHAR, a non-profit foundation. No portion of the TIGHAR Website may be reproduced by xerographic, photographic, digital or any other means for any purpose. No portion of the TIGHAR Website may be stored in a retrieval system, copied, transmitted or transferred in any form or by any means, whether electronic, mechanical, digital, photographic, magnetic or otherwise, for any purpose without the express, written permission of TIGHAR. All rights reserved.

Contact us at: info@tighar.org • Phone: 610-467-1937 • Membership formwebmaster@tighar.org

Powered by MySQL SMF 2.0.15 | SMF © 2017, Simple Machines Powered by PHP