Antennas By N6LF

A note on floating short circuited loops for inductor tuning.

In older equipment (circa WWII) we occasionally see a short circuited loop or small disc inside a coil to adjust the inductance.  This certainly works but has a bad effect on coil Q.  Attached is a very short note on a experimental test of this type of inductance adjustment.  Download Chapter 6 tuning loop note

New 630 transmitting antenna a WD2XSH/20

I have recently rebuilt my 630m antenna to use a counterpoise in place of the radial system of 128 wires lying on the ground.  I wanted to see if a much simple counterpoise system would provide comparable efficiency.  Take a look at: Download N6LF Transmit Antenna July 2017

630m-2200m talk

I gave a short talk last night to some local hams on our new 630m and 2200m bands.  Here is PowerPoint file for that talk: Download 2200 and 630m Presentation -2   that's a .ppt file.  For new software using the .pptx format: Download 2200 and 630m Presentation -2 . 

LF-MF antenna notes

 

The present draft of these notes, while far from perfect, may be helpful to many amateurs.  For that reason I've posted them in their present form with the understanding they will be revised, probably several times, in the coming years. 

By all means let me know if I've forgotten something useful and, even more importantly, if I've made a mistake!  A lot of other peoples work has been included but the mistakes are all mine!

GL and 73, Rudy N6LF, WD2XSH/20

LF-MF notes: 

Download Preface-Table of contents

Download Chapter 1  LF-MF overview

Download Chapter 2  Simple verticals w/o top-loading

Download Chapter 3   Top-loaded verticals

Download Chapter 4   Inductive loading and multiple tuning

Download Chapter 5  Ground systems

 Download Chapter 6  tuning inductor design

 

 

Paralling MOSFET's

Many people will want to use power MOSFET's in their amplifiers for 630m.  Very often it's necessary to use parallel MOSFET's to get the desired power.  Here is a technical article I wrote some 30 years ago for Siliconix Corp. : Download Siliconix Parallel MOSFET's .

SeaPac 2014 630m talk

On Saturday June 7th I gave a talk at SeaPac 2014.  You can download the PowerPoint presentation here: Download Sea-Pac 2014 Presentation .  I should add that the Flex Radio 1500 and 6000 series SDR's can transmit on 630m.  I spoke with the K3 folks and while the K3 will not operate directly that low in frequency they have modified the software to be compatible with transverters.

For true LF operation read this: http://www.arrl.org/news/radio-amateur-s-sub-9-khz-vlf-signal-detected-across-the-atlantic . 

73, Rudy

Graphing WSPR data for 630m

WSPR is a great propagation testing tool and we've had a lot of activity on 630 m of late.  I'd like to extract as much information from the WSPR data as possible so I've been copying selected data from the WSPRnet data base, pasting it into an Excel spreadsheet and the massaging it a bit.  It's been interesting and I've written up a short note on this work to date:  Download WSPR data with Excel .  73, Rudy

New 600m station at N6LF

Last November I moved to a new QTH.  Since then I've built up a new 600m station which is described at: Download New 600 meter station at WD2XSH.

630m Antenna Support Poles at N6LF

I have recently moved to a new QTH with several acres of clear farmland but no trees for antenna supports.  So I had to come up with a means to support a large 630m umbrella vertical and other experiments with wire antennas.  Here's what I did: Download Saginaw antenna support poles . 

630 meter antennas

At the last World Administrative conference a new amateur band on 630m (472-479 kHz) was authorized.  Hopefully in the near future our respective FCC's will authorize amateur operation on this new band. 

Other than some experimental licenses amateurs haven't been allowed below 160m for over 100 years so few amateurs have any experience with MF antennas.  I've been part of the ARRL sponsored 600m experimental group for several years and over that time have built several antennas for 600 and 630m.  I feel that if this band is to "take off" those of us who have been operating on MF need to share our experience.  With that in mind I have begun a multi-part series of articles on antennas for 630m.  Parts 1 and 2 are now available: Download 600m verticals part 1 and Download 600m verticals part 2.  These two parts are mostly a NEC modeling study which is fine but we still need experimental confirmation.  Part 3 of the series will be a description of actual antennas which have been built and tested.  I am currently engaged in building and testing several antennas for 630m.  The results should be available late this fall and will be summarized in part 3 of the series.