WWII HF communications reliability question

Discussion in 'Ham Radio Discussions' started by K9KQX, Oct 15, 2020.

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  1. SM0AOM

    SM0AOM Ham Member QRZ Page

    German radio engineering preferred "quality over quantity", and built beautifully engineered equipment, but in limited quantities and at a high cost.

    Also, they lacked quantity access to natural quartz for frequency control and filters. This was reflected in the designs of the equipment which used machined tuned circuits with elaborate temperature compensation to get very good frequency stability even using VFO:s. Good frequency stability permitted the use of narrow IF bandwidths.

    A comparison can be made between the American and German "Command Sets"; the ARC-5 and FuG10 (standard issue in the He 111 and Ju 88) respectively.
    They have the same purposes, internal architectures and frequency ranges, but differ diametrically in their construction.

    Pictures below, from LA6NCA, show the internal construction of the 3-6 MHz HF receiver EK10 in FuG10:



    Their Allied counterparts were "produced in tremendous quantities for war destruction in expendable vehicles".


    German designs inspired other countries for a quite long time.

    The Soviet and Eastern Bloc 60s/70s military radio designs had a quite marked influence from the German engineering heritage.

    KG7LEA, N1VAU, KD2ACO and 6 others like this.
  2. N2EY

    N2EY Premium Subscriber QRZ Page

    I was an EE major. Never had an English class of any kind after high school.

    But even I know English spelling and grammar.
    WA1GXC likes this.
  3. N2EY

    N2EY Premium Subscriber QRZ Page

    The problem was that a 1941 submarine cable could only carry a single message. And it wasn't very fast. So messages waited in line. Routine messages waited the longest.

    The first transatlantic telephone cable (TAT-1) became operational in the 1950s.


    The original Japanese plan was for the Japanese ambassador in Washington to deliver an ultimatum to the Secretary of State early on the morning of December 7 1941. The ultimatum demanded immediate resumption of sales of oil and other materials to Japan from the USA, and other changes in US policy, or a state of war would exist. The deadline was extremely short. The ultimatum was designed to be rejected, and when rejected, a state a war would exist.

    The Japanese would then attack Pearl Harbor and other US installations in the Pacific, wiping out the Fleet and forcing negotiations.

    But the Japanese made two mistakes.

    First, they didn't allow enough time for their limited embassy personnel to copy, decode, translate, type, proofread and deliver the ultimatum, which was a long and precise document. By the time it was actually delivered to the Secretary of State, Pearl Harbor had been attacked. This made Pearl Harbor a "sneak attack" and destroyed any possibility of a short war with a negotiated end.

    Second, the Japanese did not have a real intelligence network, and did not know that the most important targets of the USN Pacific Fleet (aircraft carriers) were not in port at the time of the attack.

    Third, having achieved total surprise and mass destruction, the Japanese did not send a third and fourth wave of planes to maximize the destruction. Many important targets, such as the oil tank farm, were left untouched. The pilots wanted to go, but the admiral in charge said no and took the task force back to Japan. His action was driven by the fact that the American aircraft carriers were not in port and he didn't know where they were, so an attack could happen at any time. In reality, the American carriers had no idea where the Japanese forces were, so there was no danger.
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  4. N3HGB

    N3HGB Ham Member QRZ Page

    A daily long range patrol out of Hawaii would sure have changed history.
    K0UO and N2EY like this.
  5. NN3W

    NN3W Ham Member QRZ Page

    Nagumo was a cautious admiral which was a stark contrast to his army counterparts who often would attack at any opportunity. After the second wave, he indeed feared US submarine and carrier abilities even though the US Navy had no earthly idea where the Japanese fleet was. His lack of decisiveness also came to bite him at the Battle of Midway when for about 15 minutes he was unable to decide if he should launch a second strike against Midway or to have his attack aircraft partially re-armed for torpedoes based on a siting of at least on U.S. carrier in the vicinity.
    K0UO likes this.
  6. N2EY

    N2EY Premium Subscriber QRZ Page

    Actually a series of patrols would have probably found the IJN task force, and as you say, changed history.

    The problem was one of mindset:

    - The top brass thought the Japanese would not attack without a declaration of war.

    - It was thought that the IJN could not assemble a task force and cross the world's largest ocean to within striking range of Hawaii without being detected.

    - Japan was not center stage until December 7, 1941. The war in Europe was where most American attention was focused; Europe was much closer and the shooting war had been raging there for over 2 years. U-boats were sinking Allied ships daily and the UK was being bombed nightly. Japan was far away and considered to be a minor threat by many, plus racism caused many Americans to think the Japanese weren't a serious threat. (Look at how WW2 cartoons depict enemy soldiers and sailors.....)

    - Pearl Harbor was thought to be safe from aerial torpedo attack. When a WW2-era torpedo bomber makes an attack on a ship, the dropped torpedo sinks quite far below the surface before depth control can take over and bring it to the preset depth. The harbor was thought to be too shallow for such attacks and that aerial torpedoes would just bury themselves in the mud at the bottom. The Japanese knew the harbor was shallow and developed special torpedoes and techniques to deal with the shallow water - and their techniques worked.

    - Because of the above, the main threat was imagined to be sabotage, not an aerial attack. So aircraft were parked all together near hangars, not spread out and camoflauged. Ammunition was locked up rather than being ready for use. Etc.
    W9FL, KC2XU and WA1GXC like this.
  7. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Other factors:

    -Navy patrol planes had maintained continuous full-coverage patrols for several weeks prior to Dec. 7th. This caused considerable wear and tear on the planes and particularly engines. After no change in the status quo, the decision was made to stop continuous patrols in order to repair equipment and conserve limited aircraft and parts resources. Limited patrols continued, in addition to Ready Alert planes.

    [Note: It can't be emphasized enough the limited resources available to the military prior to Dec. 7th. They were still operating basically on Depression era budgeting and equippage. The floodgates of money and material would only be released as a trickle after the attack. It would still take into late 1942 before significant effects were realized in the fleet/field.]

    -The general consensus among navy leaders was that US forces in the Philippines were the most likely first target given its' more strategic location. This meant that there would be at least a short warning to mobilize Hawaii.
    Last edited: Oct 17, 2020
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  8. WA1GXC

    WA1GXC Ham Member QRZ Page

    "Army hotheads", I believe one of the Imperial Navy admirals remarks in Tora Tora Tora.. There was a cultural clash between the Army, with the legacy of the Warrior's Code (Bushido, from the Samurai)
    and the more circumspect intellectualism of the Navy. Several Navy flag-rank officers had received university education in the US.
  9. G8ADD

    G8ADD Ham Member QRZ Page

    This beam was quickly spotted and the initial countermeasures were quite crude. Radio frequency diathermy units were requisitioned from hospitals, modified and used to "bend" the beam. In the case of my home city, Birmingham, they succeeded in bending the beam so that bombs were dropped in the suburbs and countryside some four miles south of the city centre. Some gaps in the housing dating from those raids still exist.

    Attempts to use the same system against the Germans in the night bomber raids had poor success, because while the German bombers flew from French bases near the coast, the British targets were too far inland and outside effective range.
    KD2ACO and WA1GXC like this.
  10. WZ7U

    WZ7U Ham Member QRZ Page

    I bet Anna Reitsch could kick your butt. All our butts. What a feisty lady! Yikes
    I bet Anna Reitsch could kick your butt. All our butts. What a feisty lady! Yikes, did you see that glider? :eek:
    Still in hour 3, working on it.
    K4PIH, K0UO and PU2OZT like this.

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