My thoughts on MF and LF.

Discussion in 'The Low Bands - 630/2200 Meters - VLF' started by WA4ILH, Nov 9, 2017.

ad: L-HROutlet
ad: l-rl
ad: l-assoc
ad: Subscribe
  1. WA4ILH

    WA4ILH Subscriber QRZ Page

    But in the movie Crimson Tide (Denzel Washington & Gene Hackman) the radioman, after he finally gets the receiver repaired, is receiving an EAM at what looks like about 1200 baud on VLF. LOL. Also, while trying to solder a connection, he gets blue and green sparks from the PCB.
    Tom WA4ILH
     
  2. K9STH

    K9STH Ham Member Staff Member QRZ Page

    QAA:

    I had looked at a couple of the Internet sites about TACAMO and was led to believe that the ELF was still in use. However, since my involvement with TACAMO ended in 1969, I am definitely not "up to date" about the system! o_O

    Glen, K9STH
     
  3. WA4ILH

    WA4ILH Subscriber QRZ Page

    I don't know about other DoD agencies or National Command Authority but the Navy's ELF sites in Michigan and Wisconsin were decommissioned years ago. One of my supervisors who had a PHD in Physics once told me that that ELF systems (below 3 KHz) was not really radio but "Induction" Hmmmmm.
    Tom WA4ILH
     
    KB4QAA likes this.
  4. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    Yes Glen, the ELF system was decommissioned shortly after the end of the Cold War. TACAMO was never capable of transmitting on ELF. Their system is VLF.

    Interesting Tidbit: When the TACAMO program transitioned from the C-130's to the EC-6, the winch system was removed and installed in the new planes. Still going strong after 45+ years.

    p.s. I live here by Pax River Md. I was a boy here when TACAMO started up; my dad was a navy test pilot. Have had navy buddies in the program. Can provide some interesting stories from Bermuda deployments with the TACAMO guys.
     
  5. K9STH

    K9STH Ham Member Staff Member QRZ Page

    The airborne system was VLF and the land based was ELF. It was the airborne system that my division (Process Division) at Collins Radio Company was most involved. Process Division made the circuit boards for the other Collins Radio divisions. Since the amateur radio products were "hand wired" at the time, we did not have anything to do with those products during the period in which I was employed.

    The Collins Radio engineers, and technicians, who flew with the Navy during those early days, also had some "stories" to tell about their experiences. One had to have at least a secret security clearance to be even slightly associated with the project. I almost had to get a "Q clearance" because of the Sandia Base project. However, I left Collins Radio to go to work for a microelectronics firm. At that time, I was in a position to know that Collins Radio Company was undergoing some financial difficulties (Art Collins sold out to Rockwell International finally in 1973). However, I got 2-salary raises at the same time but the microelectronics company offered me a 50% increase in salary over what I was making with the raises. It was a "no brainer" and I left Collins.

    Glen, K9STH
     
  6. KM1H

    KM1H Subscriber QRZ Page

    While I understand the benefits of salt water (28 years in the USN active and reserves) a perfect ground and almost zero degrees elevation angle with a vertical TX antenna; I have done extremely well on a very very lossy granite hilltop in NH that is far from the salt water benefits. For RX on the BCB thru 30M there are 5 2 wire 500-750' Beverages for 10 directions , and full 1/4 wave size verticals on 160 and 80 with elevated radials for TX, the latter are good for over 300/350 DXCC respectively with no more than 1200W. Also first JA on 160 and 5BWAZ from New England plus many USA DX and WPX contest wins were helped by those two bands.

    A Beverage is a vertically polarized slow wave antenna with the major elevation lobe around 25-30 degrees due to the tilted wavefront and totally useless over salt anything. It prefers a lossy ground as many found out when they moved to salt marsh areas. They had great TX signals to far DX but were alligators on receive when bands were noisy and man made crud became a huge problem.

    Since ham radio is far different than commercial/military use many do not understand the finer points.

    Carl
     
  7. W0AAT

    W0AAT XML Subscriber QRZ Page

    Never knew that about beverage antennas... with the super rich farm land around here and low ground resistance might not be a good choice for me...
     
  8. K8JD

    K8JD Ham Member QRZ Page

    I wonder if the tons of steel under the antenna on a large Navy ship had any thing to do with the counterpoise efficiency ???? :eek: Maybe not so much the salt water ?
     
  9. KL7AJ

    KL7AJ Premium Subscriber QRZ Page

    What a lot of folks don't realize is that the top end of the AM broadcast band is THREE TIMES the frequency of the bottom end, and has entirely different propagation. Low end AM broadcasting has amazing ground wave....even here in Alaska, where the ground conductivity sucketh mightily.

    There are three NDB's I can receive here quite nicely with a crystal radio!

    Eric the Lowfer
     
  10. KM1H

    KM1H Subscriber QRZ Page

    Im not really sure about actual groundwave propagation as I hear stations in the same city about as well at either end running the same power. There are also more 50KW stations at the low end and few at the high end.
    Long distance propagation on 630 and 160M are similar with 630 taking the edge likely due to lower RF ground losses based on FT8 reports with fleapower. More experience is needed on my part.
    Grayline propagation is better and longer on 80 than 160 at least at my Lat and Long.

    Carl
     

Share This Page