Radio Equipment


Dennis Smith

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Aug 24, 2002
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Hi All,
After reading Marconi`s submission the the British Enquiry, I see that not a lot had changed up to the time I was made redundant in 1989.

However I have two questions to put:-

1) Storage Batteries - I presume these are lead/acid cells - when were these invented? - What sort of BANK of batteries are we talking about here (Voltage and Current supply, current for the Ampere Hour Duration etc.) I presume the Voltage was the nominal ship`s voltage ie. 100 volts (I think - Oh no I`m going to be wrong-again!!), if that is the case, it`s going to be a big bank of batteries. How were they kept fully charged, was there a "trickle charge" all the time or was it up to the operators to charge them themselves when required? Where were they stored, Marconi says in the Wireless Cabin, the Radio Room as we now know it? Sounds a bit dodgy to me, all that hydrogen floating round with a spark gap transmitter, also what about corrosion, that would have had to have been a problem.

2) What was the duplication that Marconi talks about ie. The essential points of the apparatus were in duplicate. Did this mean there were 2 transmitters and 2 receivers, or is it just bits and bobs that were duplicated?

Hope for some answers (Hope you`re about Parks)

Best wishes and regards

Dennis
 
Mar 3, 1998
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Dennis,

Sorry for the late reply...I was occupied in another discussion, but I'm free of that now.

I'm writing a detailed description of the Marconi apparatus, but it won't be published until 2004. I don't want to give too much away before then, especially since my analysis of the wreck footage is still ongoing. The Antique Wireless Association, though, published a condensed version of my draft for their members a couple of months ago, so I'll quote from that:

<font color="#000066">Accumulators – A battery of 8 chloride accumulators stored direct current from the ship’s mains for use by the wireless set in the event of a shipboard electrical casualty. During normal operation, the accumulators were charged by the ship’s dynamos and required little attention. Upon loss of power from the ship’s mains, the operator could discharge the accumulators through a 10” induction coil by using the Emergency Key. Eight accumulators were provided in order to provide the necessary E.M.F. to work the emergency spark coil. The cells in each battery were arranged in series, with positive connected to negative, leaving a positive terminal at one end and a negative at the other. Cells were deep enough to allow the lead plates to be covered with dilute sulphuric acid at all ordinary angles of heel. The movement of the ship actually helped the accumulators keep the electrolyte at a uniform specific gravity, as it kept the acid from settling in layers of varying densities. The acid would boil toward the ends of charging, but spraying was prevented by covers. The operator had to ensure that no naked-flame lights were used near the cells when the accumulators were fully charged, because the amount of hydrogen released during the process could be ignited by contact with a light source. The operator monitored the voltmeter mounted on the Charging Switchboard during operation of the emergency set to guard against the occurrence of sulphating in the accumulator cells, a condition where the lead plates were coated with a white insulating skin of sulphate of lead which rendered the plates electrolytically inert and gave the cell a high resistance and low capacity. Normal (non-emergency) discharging of the cells had to be terminated when a reading of 14.5-15 volts was indicated; otherwise, permanent sulphating of the cells would occur.

Charging Switchboard (Fig. 29) РThe switchboard used for the emergency set was a Marine Type Switchboard, No. 1. The operator could control the discharging and charging of the accumulators through use of multi-point switches on the switchboard. The position of the double pole three-way switch connected the ship's dynamos to the accumulators and determined the direction of the charging current through the battery. Two 50 c.p. carbon filament lamps provided a visual indication that the proper connection had been made for charging the batteries. The position of the D.P. switch that provided proper charging would cause the lamps to glow least brightly. The single pole three-way switch was used to connect the induction coil into the circuit. A 15-amp̬re fuse inserted between the coil and accumulator terminals along the bottom of the switchboard protected the coil when working off the accumulators; the two connected to the fuse terminals protected the coil from the main charging and working circuits. Because the accumulators were not used in normal operation, a series of twelve 4-ohm charging resistance coils were inserted into the charging circuit to slow the charging rate. The filament lamps were wired in series with the charging circuit and allowed a charging current of 4-amp̬res to pass. Since the charging rate of the battery was nominally 12-amp̬res, long charges were required to fully refresh a depleted battery. When the battery of accumulators was fully charged and charging current still passing, the operator would read approximately 20.8-volts on the supplied voltmeter. At that point, gas would be freely bubbling from both positive and negative plates. With the charging current removed, the reading fell to around 17-volts, or 2.1-volts per cell. Because permanent sulphating would occur when the voltage in any individual cell in the battery fell below 1.85, the operator took care not to allow the total voltage as shown on the voltmeter to fall below 14.5-15-volts, which equated to 1.17 specific gravity of the acid.

I'll have more detail in my final work. In addition, you'll be able to see the battery boxes in the re-creation of the Silent Room in the "Ghosts of the Abyss" companion book coming out in March.

As far as duplicate components were concerned: Titanic carried two receivers. The Magnetic Detector/Multiple Tuner was the receiver most used as it was simple and "sailor-proof." A Marconi Fleming-valve receiver sat next to the Multiple Tuner and could be switched into the circuit via a two-way switch. The valve receiver needed a 4-volt source to power the valves' filaments, so 2 battery boxes and a charging switchboard were supplied in the Marconi Room (also visible in the Marconi Room re-creation in the "Ghosts" book). The valve receiver was actually a better receiver than the "Maggie"/tuner combination, but took more skill to operate. Both would eventually be replaced by crystal sets.

As far as transmitters are concerned, a spark could be generated using both windings of the transformer, one winding of the transformer (reduced output), or via the induction coil of the Emergency Set. There were two spark gaps...the disc discharger at the aft end of the motor-generator set in the Silent Room and on the induction coil in the Marconi Room. A buzzer was supplied that was used for extremely close-range communication and circuit testing, but the noise it created wouldn't carry very far.

There were two switches to cut ship's power from the set, 4 condensers, two windings in the transformer, 8 accumulators for the Emergency Set...all these were needed for normal operation, but they could be reconfigured in the event of a casualty.

Parks
 

Dennis Smith

Member
Aug 24, 2002
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Parks,
First let me apologize for the delay in replying.
Thanks very much for the info, most of which made sense, the rest I'll re-read after a big plate of fish, just to get the brain cells working. By Maggie/tuner combination, I presume you mean Magnetron / Klystron tuner, which comes as a bit of shock to me, as I though the Magnetron was only invented just prior to or at the start of WW2 with the invention of VHF / UHF RADAR.
Amazing what you can find out on this website.

Best Wishes and Rgds

Dennis
 
Mar 3, 1998
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Dennis,

No, no..."Maggie" was the colloquial term used to describe the Marconi Magnetic Detector, a clockwork-driven mechanism that was used to convert radio-frequent oscillations into vibrations that excited the diaphragms in the operator's headset. The Maggie was used in conjuction with the Marconi Multiple Tuner, a relatively simple device that allowed the operator to tune the aerial primarily to one of the two then-standard operating wavelengths (300- and 600-metre). Much more primitive apparatus compared to the radar set devices you mentioned.

It's a coincidence that you should mention the magnetron. Perfecting and mass-producing the magnetron during the war proved to be the catalyst of growth for my current employer, Raytheon.

73,
Parks
 

Dennis Smith

Member
Aug 24, 2002
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Parks,
Whoops,should have thought more before sending that last post, I said I knew the
magnetron wasn't invented until late 30's or early 40's, if I knew that, why did I make that stupid assumption, thanks for correcting me.

With regard to Raytheon, I've sailed on a couple of ships with Raytheon Radio gear and radars on board and I must say I didn't have any problems with it (Good Gear). However most of the equipment I sailed with was Marconi (I also did my training on Mimco gear), and I found it simple to operate and fairly straight forward to maintain and repair.
Again, thanks for the info Parks, much appreciated

Best wishes and Rgds

Dennis
 
May 3, 2005
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Just an observation from this nitpicker on a comparison of Marconi Room scenes in "A Night To Remember" (1958) and "Titanic" (1997).

In "ANTR" the drums on the Marconi Detector are shown rotating, which is correct if signals were to be received. However, in a later scene Third Officer Groves enters the Marconi Room after Marconi Operator Evans has gone to sleep. The Titanic's distress signals are heard (the signals being played in the movie have been determined to be accurate in a previous thread) but apparently Groves puts the headphones down and turns off the set because he can't understand the code. Actually, I believe the detector spring wound motor had run down and Groves would have heard nothing.

In "Titanic" the drums are shown stationary - not rotating - but apparently Philips and Bride are receiving signals. (This is shown also in the deleted scene.)

You can watch the white dots on the drums to see if they are /or/ are not rotating.

Question: How long did the spring wound motor run after being wound ? (In "ANTR" Evans is shown winding the detector just before going to bed.)

73,
Robert
 
May 3, 2005
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Dennis Smith quote.:
>>With regard to Raytheon, I've sailed on a couple of ships with Raytheon Radio gear and radars on board and I must say I didn't have any problems with it (Good Gear).<<

I only had limited experience on shipboard radar, but same with Raytheon....no major problems (Good Gear.)

This might have been answered previously on another thread.:
If you were to build a model of the Marconi Magnetic Detector would you hear anything from present day radio signals ?
 
Mar 3, 1998
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Robert,

A guy down in Oz (or was it NZ?) built a working model of a Maggie and even wrote a book about it. I don't know, however, if he tried to put it to a practical test.

The detector, if connected to an aerial, would still be excited by any electromagnetic oscillations in the atmosphere (of which there probably are many in today's electronically-polluted environment) of the same wavelength as the aerial, but I would think that it would come across as simple background noise (a telegrapher of past times would refer to it as "X"s). All the Maggie does is amplify oscillations picked up by the aerial...it's a simple device with a simple function that would still work as intended today. Only problem is, signals sent today encode the transmitted intellegence in the constant stream of a carrier wave. The Maggie was designed to pick up interruptions in the wave itself...interruptions that were designed along patterns of duration (dits and dahs) that were recognisable to the operator.

But, let's say that you have a modern ham operator sending Morse on 500kHz...would the Maggie pick that up (assume that the aerial can be tuned to the exact same wavelength)? The dits and dahs of the modern message would still be sent inside a carrier wave, so the chances are that the Maggie would detect noise on the frequency, but not the specific intelligence being transmitted in the wave.

Parks
 

Dennis Smith

Member
Aug 24, 2002
166
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Parks,

So what you are saying is that if someone were to send morse using CW rather than MCW (Modulated Carrier Wave) the signal would be heard using a "Maggie". I ask this because nowadays an audio frequency would have to be injected at the receiver using a BFO (Beat Frequency Oscillator) to create an audio tone to modulate the incoming CW and then filter out the CW to leave just the audio at the speaker (Headphones) Hope that makes sense!! Sounds much more complicated than using the old "Maggie"

Best Wishes and Rgds

Dennis
 
Mar 3, 1998
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Dennis,

No, what I am saying is that the Maggie can't distinguish any signals out of a continuous or carrier wave.

Let's examine the basics of how the Maggie works. A rotating iron band passes underneath two sets of magnets. When electromagnetic energy vibrates/excites the aerial and flows down the leads into the detector, the extra energy causes a momentary deflection in the band. This deflection is detected by coils that converts the deflection into an electrical pulse that is later amplified (through the telephone converter) into a sound (created by movement of the diaphragm in the headphone) that the operator can hear. It's as simple as that. It's a completely un-modulated system and is dependent solely on the interruption of a high power discharge to form a recognisable pattern (Morse code). Does that make it any clearer?

Parks
 

Dennis Smith

Member
Aug 24, 2002
166
3
171
Parks,

Thanks very much for the explanation of how the "Maggie" worked, it certainly makes more sense now.

Cheers again

Best Wishes and Rgds

Dennis
 
May 3, 2005
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Parks-

Question #1: In other words, what you hear on a "Maggie" sounds like what you send - as long as it's a spark transmission - and assuming you are using the same type transmitter on both ends ?

Question #2 - Was there some sort of relay or switch to silence the receiver during transmissions ?

Question #3 - Was there some sort of "sidetone" for the transmitting operator to monitor his spark transmissions ?

73,

Robert
 
Mar 3, 1998
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Robert,

#1: The received spark sounded like the transmitted spark, depending upon atmospheric distortions/interference. However, the received spark was converted and filtered as it passed through the Maggie, telephone converter and headphones. The character of the spark depended on the transmitting station's operating frequency and power. Titanic's rotary-spark generated a train of sparks that combined created a musical note, distinguishing it from the plain-spark transmitters on the other ships in the area.

#2: There was no change-over switch in the Marconi system...instead, a device called an earth arrester spark gap was used to distinguish between transmitted and received signals. Essentially, it included a gap that was wide enough to insulate weak received currents (which were subsequently sent to the receiver) but allow stronger transmitted currents to jump across and continue to the aerial. It was also used as protection against lightning...the strong electrical current would jump the gap and be routed to earth.

#3: No sidetone on the spark set. The operator could hear the spark at the contacts on his key.

73,
Parks
 
May 3, 2005
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Parks-

Thanks very much for your explanation(s).

#2- Something like a T/R tube on a radar ? (I'm thinking WWII-Korea vintage search radars.)

Rest of the questions (#1 and #3) were results in thinking from being infected in the disease known as "Ham Radio". LOL.

73,
Robert
 
May 3, 2005
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I see this thread has been a bit inactive for a while.....sooo.

Question #1- (May have been answered on another post...couldn't find it.) Would it have been possible to hear Titanic's signals at other locations. I "invented" sort of a sci-fi story in which a teen-age Ben Calvert (Rose's future hubby)
picks up Titanic's CQD/SOS in Cedar Rapids,Iowa. Would his have been possible ?

Question #2: In ANTR and other "Titanic" movies Bride tells Phillips that "power is going" and a scene shows the meter needle going down. There was, I believe, emergency battery power provision for the Marconi transmitter ? Could transmissions have been continued in that manner ?...Or maybe they considered Titanic was too far gone to try that anyway ?

I notice that some of the more amateur questions such as these get some rather curt answers from the experts, so I am prepared to receive same and will not consider them as insults, so you may fire when ready, Gridley ! LOL.
 
May 3, 2005
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(Re:Question #2)- Considering the Marconi Magnetic Detector was more or less a passive device and did not require power (other than winding the detector)it would seem that receiving could have continued after power was lost to the transmitter until the antenna or its connections broke or went under water ? Is this a correct assumption ?
 
Mar 22, 2003
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Hi Robert.

1. If its fiction don't worry about such details as Cedar Rapids being too far away. By the way, that story about David Sarnoff picking up the Titanic signals from atop Warnamaker's department store in NY city is a bit of creative story telling. He was not on duty the night Titanic went down and the earliest documented message he received was on April 16 from the Carpathia on her way back to NY. Most of what was written about him and the Titanic disaster is mythology.

2. As I understand it, there was a battery operated emergency set on board but there was no need to use it. By time they left the wireless cabin the ship had only a few more minutes left.

3. The mag detector was a passive device and would have worked independent of transmitter power as long as it was wound up. You can build your own passive AM radio detector today if you care to. That's all you need is a tunable coil with a long attached wire and an alligator clip to clip onto an electrical ground (like a metal screw of an electrical outlet), a capacitor, a diode, and an earpiece. When I was kid I built one, and was able to listen to Yankee baseball games at night during school nights while pretending to be asleep in bed. Living in the Bronx some the radio station signals at night were quite good, but depended on how far away the transmitting towers were from where you actually lived.
 
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May 3, 2005
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Hi Sam-

1.I've heard the same debunking of the Sarnoff myth too. I was going to work in Arthur Collins in the story, but checking his biography found he was born in 1909....that would have been a bit of creative story telling...a real child prodigy of three years old building a radio and knowing Morse Code ! LOL. However, the fictional "Ben Calvert" (of "Titanic" 1997) would have probably been about the right age, interest group and location for the story.

2. Just guessing...probably Phillips and Bride had the word that Carpathia was the only ship on the way, and that any further efforts would have been useless anyway ?

3. I built many a "crystal set" in my younger days, with varying results of success. I graduated from "cat's whiskers" to 1N34A's for the diode detector. There were some plans for a "foxhole radio" that used a razor blade and a safety pin for a detector, but I never could make it work.

Of all the "Worst Titanic Movies" ever made, that miniature transmitter in one of the other versions is the most ridiculous. IMHO, that is.

Regards,
Robert

PS- Thanks for the kindness to us rank amateurs.
Well....at least I do have a license from the FCC to prove that I am an amateur. LOL.
 

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