|
Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
|
Thread Tools |
27th Jun 2021, 8:19 pm | #21 | |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
|
Re: The holy grail of antennas
Quote:
|
|
28th Jun 2021, 10:13 pm | #22 |
Heptode
Join Date: Jan 2008
Location: Ashhurst, Manawatu, New Zealand
Posts: 570
|
Re: The holy grail of antennas
Clark Masts. There's a blast from the past - way back in the late 60's I worked for the CAA at the engineering workshops near Gatwick. We had a couple of Series 2 LWB Landrovers with 70ft masts with a load of equipment in the back. They were used to investigate radiation patterns of the glideslope transmitter antennas and some remote monitoring. We nearly lost one when a newbie forgot to extend the support legs.
__________________
Cheers - Martin ZL2MC |
7th Jul 2021, 4:19 pm | #23 |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
|
Re: The holy grail of antennas
Bit of sporadic E. the last station on the video has an interesting echo. Unsure whether multipath or some fancy echo mike
https://youtu.be/VDVlw6LPqPA |
7th Jul 2021, 7:03 pm | #24 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
|
Re: The holy grail of antennas
I bought a couple of these as I had a twin 5/16" dipole mount ;
https://www.radioworld.co.uk/radiowo...-cb-radio-fire The dipole antenna without adjustment is resonant at 25.9MHz (close enough for 24MHz) and I use it horizontal - will tune to 28 MHz with ATU. |
9th Jul 2021, 10:45 pm | #25 | |
Pentode
Join Date: Nov 2018
Location: Freckleton, Lancashire, UK.
Posts: 232
|
Re: The holy grail of antennas
Quote:
Phil Karne an ex co-worker did quite a 'number' on it - worth a read, here's a snippet Introduction Mr. Walker has invented a family of modulation schemes he calls Very Minimum Shift Keying, or VMSK. He claims VMSK achieves spectral efficiencies of 90 bits/sec/Hz or more while requiring no more power than conventional modulation methods such as BPSK. These claims are in direct violation of the mathematical principles of digital communications discovered by Harry Nyquist (1928), Claude Shannon (1948), and others. These fundamental principles are as firmly established as the laws of thermodynamics; neither is at all controversial among competent engineers. Unfortunately, thermodynamics and communications theory are arcane (and related) subjects that many laymen either misunderstand or refuse to accept. Hence we still have cranks trying to build perpetual motion machines. And we have Mr. Walker and his VMSK. My interest in debunking VMSK is very simple: people are investing real money in a technology that can't possibly meet its inventor's claims. And since the subject falls into my personal field of expertise, I feel a civic duty to speak out. http://www.ka9q.net/vmsk/ Mods, feel free to delete if too far off topic.
__________________
Building and tinkering for over 50 years, from 807's to digital amateur TV. |
|
9th Jul 2021, 11:13 pm | #26 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,864
|
Re: The holy grail of antennas
Yes, we're at risk of the thread turning into a collection of daft theories. We'd better steer back to antennae.
(As for VMSK... look up 'Stenode Reception' and you'll find it wasn't new. But that would be a whole new thread.) David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |