During the weekly F-troop there are mentions of software, websites and solutions that are worth taking note of. This website attempts to document them.

20180811 -Bucking and Boosting

posted Aug 10, 2018, 6:04 PM by Onno Benschop   [ updated Aug 10, 2018, 6:04 PM ]

Steve VK6CS explains Bucking and Boosting in his YouTube channel:

20180804 - 80m antennas from the audience

posted Aug 3, 2018, 6:31 PM by Onno Benschop   [ updated Aug 10, 2018, 5:16 PM ]

Charles Nk8o:
My current primary antenna is an 88’ (26.82m) symmetrical doublet at 44’ or 13.41m per leg. Elevation is 15m above ground level, strung between two trees.  This is fed with window line as far as the entry point to the shack.  A 1:1 balun is used to couple the balanced to unbalanced connection, and of course, an ATU between the radio and the antenna (or in the radio).  I use this antenna on 80 through 6 meters with acceptable results.

Mark VK6BSA:

Denis VK6AKR
2m and 70cm pogo stick constructed for me yonks ago with Allan VK6MST

2m and 70cm crossed yagi for satellite working - when I get around to finishing it, that is!

40, 20, 10 OCF dipole kindly given to me by Andrew VK6AS - taken down in prep for move to new QTH and previously has been in use for several field days including JMMFD with the WA VHF Group

80, 40, 20, 17, 10m a series of spiral wound vertical whips interchangeable on a spring base.   Originally designed for vehicle roo bar installation but modified for use with photographic light tripod as a base.   These have been in use with the FreeDV experiments despite non-optimal polarisation and shielding by buildings.

Magnetic loop (dual loops at 90 degrees) tunes well on 40m - constructed by Roger VK6FRAN   Needs a better capacitor and a means of remotely adjusting (geared motor, stepper, etc)

Mag loop from yellow gas tubing (metalised inner) - this is not yet functional, still considering the best way to implement a variable high voltage capacitor.

When I look back on the list it looks impressive but in fact only maybe 10% of the above are viable at present due to either not being finished or awaiting installation at new QTH.

Pipe-dream antennas - definitely a fan dipole a la VK3YSP and VK3FOWL (in AR magazine a few years ago they described it.)   More (and ever-better) mag loops.   I see these as the future for situations like mine where real estate is limited.   Microwave antennas and waveguides, etc as my interests expand into that area


20180804 - NK80 update

posted Aug 3, 2018, 6:30 PM by Onno Benschop   [ updated Aug 3, 2018, 6:35 PM ]

Charles NK8O has been playing in the park and took delivery of a spiffy new case:

Tuned wire vertical, 20 meters, with two radials.

I used a tuner in line because the QCX radio is not very tolerant of SWR mismatch.

QCX in operation.  11.2V Li-ion battery.  Kept it simple with a straight key.

Lower portion of the QCX case. Radio is a perfect fit!

The “other” QCX, 40 meter version.  The case does look spiffy.

20180804 - Network Radio

posted Aug 3, 2018, 6:28 PM by Onno Benschop

John VK6JB shares this quick and dirty video of a snippet from this week's F-Troop via Network Radio:
#irn #youtube #vk6jb

20180804 - 10m - 80m Antenna

posted Aug 3, 2018, 5:58 PM by Onno Benschop

Richard W4JXA sends in this suggestion for an antenna:

EFHW-8010-1K about 150.00 US 10 thru 80 without a tuner. Have not tried it myself. Featured in QST March 2016 page 52. The annual ARRL antenna issue.


#antenna #w4jxa

20180804 - FreeDV

posted Aug 3, 2018, 5:26 PM by Onno Benschop

Al KP3A shares with us that he's been experimenting with FreeDV on 80m and having lots of fun:
#freedv #mode #kp3a

20180804 - Gamma Match Adjustments

posted Aug 3, 2018, 4:41 PM by Onno Benschop

Denis VK6AKR shares a story about Gamma Matching:

My first experience with the gamma match was educational.   My need was for a match to a 2m dipole for satellite working on a crossed yagi.   Desiring to have the 2m elements removable for transport, a folded dipole was unworkable.

Much research into gamma matches revealed several (conflicting) sets of dimensions and configurations for the capacitor and tapping point.   Eventually settled on a compromise design using the inner conductor and insulation of some RG213 coax, sliding inside a 10mm aluminium tube to form the capacitor and the matching line simultaneously.   So far so good.

However the VSWR would not reduce to anywhere below about 4:1 and despite moving the tapping point over its full range the VSWR variation was small.   Then it dawned upon me.   I had started with a very small capacitance indeed - the gamma tube enclosing only a small amount of the RG213 core.

Herein lay the problem.   With too little capacitance I was effectively measuring the VSWR of an open-circuit coax feedline!

So the moral of the story -- start with maximum capacitance, set the tapping point (between the tube and the antenna element) then reduce the capacitance, re-adjust the tap point, etc until the VSWR reduces to as close to 1:1 as possible.

#build #vk6akr #learning

20180721 - Baluns

posted Jul 20, 2018, 5:37 PM by Onno Benschop

Charles sends us some information about baluns:

20180721 - Spectrum Analyser

posted Jul 20, 2018, 5:33 PM by Onno Benschop

A cost effective spectrum analyser was introduced by Randall:
#spectrum-analyser #testing #vk6wr #vk6frtl

20180714 - Soldering Kits

posted Jul 15, 2018, 10:44 PM by Onno Benschop

Discussion during the net this week touched on gaining soldering skills by building kits. A list of kits can be found here:
#soldering #kits #learning

1-10 of 194