[Elecraft] Markers, etc.

[Fred Jensen]

On 12/7/2011 1:20 PM, Merv Schweigert wrote:

> I am sure that spark gap days are back,  but no one mentioned the
> gap was between the ears.

Well, actually yes.  I have a couple of Coast Guard friends from 
Vietnam, and awhile back, one of them pointed me to a LORAN-C upgrade at 
some of the stations.  The previous equipment was sort of standard 
OSC->PA architecture using BIG tubes.  Many ran in the half-MW range, 
the station at George WA was originally 1.6 MW.  After the "upgrade" it 
was running 1.2 MW.

The upgrade replaced the TX with an Accufix TX from Megapulse.  No 
tubes, no oscillators, no solid state amplifiers.  A bank of SCR's 
discharged a large capacitor bank into a resonant circuit coupled to the 
antenna.  [sound familiar?]  Other than a large adjoining room filled 
with very high-tech control equipment, cesium clocks, and bunches of 
software, it was basically a 1.2 megawatt, well controlled spark gap. 
After the properly shaped pulse was formed, the rest of the damped wave 
was eliminated by a circuit aptly named The Tail Biter.  Since the 
antenna was part of the resonant circuit, the control circuitry included 
an auto tuner that compensated for real-time antenna variations.

LORAN-C was shut down a couple of years ago, but some of the antennas 
remain [mainly top-loaded monopoles].  I wonder if a KAT500 would be 
able to load one on 160m?

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org