View Single Post
  #10 (permalink)  
Old 04-02-2017, 9:42 PM
Coyote-Frostbyte's Avatar
Coyote-Frostbyte Coyote-Frostbyte is online now
Member
   
Join Date: Feb 2016
Location: Colorado, New Mexico
Posts: 565
Default

This will be nice addition to the ham bands, though a bit long in arriving.
.
There has been a de facto, pseudo hammish band of frequencies for a long time between 160-190 Khz - but with quite severe restrictions. Some may be familiar with it-- **
.
My father played around with this band over 25 years ago- and I remember quite well some the equipment he used. He conversed with ham friends using a ~50 foot guy’d vertical with a HUGE top mounted loading coil and umbrella-like ‘top hat’ capacitor… The mode was CW, though they tried voice not too successfully… the transmitter resembled more something Tesla would have approved of than the average ham. It used a 186Khz crystal oscillator feeding a large audio frequency transistor’d PA.
In the years that followed and my experiences in VLF long had eclipsed this, my memories centre as a teenager, amazed, that the audio circuit work’d in RF... the only tuned circuit was the PA's output tank.
.
My father would tune the system by dipping that tank circuit to resonant the PA, as indicated by a large glowing Neon bulb. A pencil lead placed at the bottom of the well isolated antenna would draw a healthy +” spark, and should you brush against it, a painless, nasty RF burn. He'll probably still swear this was 1 Watt input , but…..

With this transmitter, my father routinely chatted 50-80 and more- miles to other “Low-Fers” using made up callsigns- usually their ham call prefixes. I was intrigued, but never liking CW, I wasn't intrigued enuff.
.
I mention all this, because while it seems that 5 watts ERP (630 metre’s), 1 Watt (2200 metre’s) are paltry- the regulations state ERP; not input or even transmitter output power… For the average ham to achieve this with even a 60 metre antenna, the transmitter output will need to be in the hundreds of watts- for a shorter antennas?.. Maybe at 0.5% efficiency?? well- do the math.
.
...One of my favorite LF examples is the former Naval Station NSS- with its 20Khz signal feeding an antenna system centre’d around a 1200 foot tower- with a curtain array covering acres-- One Million Watts! into it, 30 Kilowatts ERP… and this could talk to submarines submerged on the other side of the world.
.
While I'm on the subject, forget any antenna that isn’t vertically polarized…. Nothing horizontal. Everything at these frequencies will be vertically polarized ground wave- this is true ground wave, not what many hams think of when they use this term- and this will be especially true for 2200 metre’s.
There is a lot to profit by looking at the old low frequency stations-- going long wave is to step back in history.
.
These bands poise a great departure/challenge from the standard ham bands. They won’t lend themselves to the causal operator- pretty much forget voice (Bandwidth too large)-- CW will be the easiest mode- digital most like will dominate, but again, it will be BW issue. They will be for the exotic experimenter.
.
Hmmmmm , would I take the bait?
.
………………….CF
.
.
_________________________________________-
**
Part 15.217 Operation in the 160-190 Khz Band

(a) The total input power to the final radio frequency stage (exclusive of filament or heater power) shall not exceed one watt.
(b) The total length of the transmission line, antenna, and ground lead (if used) shall not exceed 15 meters.
(c) All emissions below 160 kHz or above 190 kHz shall be attenuated at least 20 dB below the level of the unmodulated carrier. Determination of compliance with the 20 dB attenuation specification may be based on measurements at the intentional radiator's antenna output terminal unless the intentional radiator uses a permanently attached antenna, in which case compliance shall be demonstrated by measuring the radiated emissions.

Last edited by Coyote-Frostbyte; 04-02-2017 at 10:00 PM..
Reply With Quote