Vintage Electronics

Making and Hacking

SOTA

Looking over Donner Lake

Vintage Electronics

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Ham Radio, Summits On The Air (SOTA), Making and Hacking and Vintage Electronics are hobbies that I enjoy. This website covers my activities in these hobbies. See my personal website to learn about my IOT garden and photography. You may also visit my QRZ.com page for my Ham Radio profile.

Interested in learning more about Me?

Listen to the Hamdom Thoughts podcast by AD6DM interviewing me about Ham Radio, Making, Hacking and SOTA

A 40 - 10 meter QMX

The QMX from QRP Labs is modified for operation from 40 to 10 meters. A perfect SOTA rig when matched to a 40 meter EFHW

Dan Koellen AI6XG

Jun 27, 20248 min read

2,766 views

4 comments

LCD Display for the KD1JV TriBander

In an earlier post I described the modifications I made to the KD1JV designed TriBander to make it more useful for SOTA. The...

Dan Koellen AI6XG

May 9, 20249 min read

334 views

3 comments

Making the KD1JV Tri-Bander More SOTA Friendly

This post outlines the modifications made to reduce receive current consumption, reduce weight and size, and change the controls and readout

Dan Koellen AI6XG

Jul 18, 202311 min read

887 views

2 comments

QRP Tube: High Voltage DC to DC Supply Evaluation

The high voltage supply for the vacuum tube transmitter needs to be low noise in the 40 meter band, efficient for battery operation and...

Dan Koellen AI6XG

May 2, 20236 min read

510 views

2 comments

QRP Tube: T/R Switch and QCX Interface and Modification

A Modified QCX and TR Switch for Vacuum Tube SOTA transmitter

Dan Koellen AI6XG

May 2, 20236 min read

442 views

2 comments

QRP Tube: Single Tube SOTA Transmitter

A single tube transmitter is developed for portable and Summits on the Air (SOTA) use. The SOTA transmitter had to be relatively...

Dan Koellen AI6XG

May 2, 202316 min read

691 views

2 comments

QRP Tube: Vacuum Tube, Battery, Lightweight, Compact, Portable: Can They Coexist?

Using vacuum tube equipment for SOTA activations? Why not! A portable battery operated vacuum tube transmitter is part of a SOTA system.

Dan Koellen AI6XG

May 2, 20235 min read

2,096 views

2 comments

All Wound Up About EFHW Transformer Winding

After successfully using an End Fed Half Wave (EFHW) antenna for SOTA, I decided to build a 10 to 80 meter EFHW antenna for my home...

Dan Koellen AI6XG

Feb 28, 20235 min read

3,363 views

2 comments

Evaluating efficiency, transformer and mismatch losses in toroid transformers - some observations.

Two methods for transformer loss are evaluated. We learn that mismatch loss must be accounted for.

Dan Koellen AI6XG

Jun 17, 20226 min read

2,195 views

1 comment

Reactive Component Measurement With the NanoVNA

Exploration of using the nanoVNA to measure inductance and capacitance at frequency of use.

Dan Koellen AI6XG

May 16, 20226 min read

3,951 views

2 comments

Toroid Transformers - How Hot Will It Get?

There are a number of factors in choosing a toroid for a RF transformer. While one may model electrical performance, calculate predicted...

Dan Koellen AI6XG

Mar 2, 202211 min read

2,471 views

0 comments

Leg Benchmark W7Y/EW-017 Activation - An Alternative Route From the West

Pole Mountain From My Operating Position Summit Trip Summary Distance: ~ 2.6 mi one way Transport: Hiking Elevation Gain: ~500 feet...

Dan Koellen AI6XG

Jul 30, 20212 min read

119 views

4 comments

Electrostatic Discharge (ESD), Does it Matter for Makers and Hackers?

Electrostatic Discharge (ESD) is a subject that can inspire a lot of discussion, head shaking and some misunderstanding. ESD damaging...

Dan Koellen AI6XG

Jul 20, 20219 min read

699 views

2 comments

Don't Fear the Smith Chart

Like many radio amateurs I was initially intimidated by the Smith chart. Transmission line and antenna theory, unfamiliar terms and...

Dan Koellen AI6XG

Jun 16, 202113 min read

2,369 views

5 comments

Schallenberger Ridge W6/NS-213 Activation - An Alternative Route

A different approach to Schallenberger Ridge from the west. A nice hike through historic train tunnels.

Dan Koellen AI6XG

Apr 26, 20213 min read

90 views

2 comments

How I Killed a Microcontroller

This blog outlines the steps taken to determine why a microcontroller no longer works, and the journey to find the damage on the chip.

Dan Koellen AI6XG

Apr 25, 20219 min read

365 views

2 comments

The Digi-Disco, a 1970's Light Controller

This is a light system that I designed and built in 1978 to control large flood lights of different colors, synchronized to disco music...

Dan Koellen AI6XG

Jan 25, 20212 min read

268 views

3 comments

Heathkit IT-28 Capacitor Checker

After building the Pico C-Super capacitor tester that was published in Elektor Magazine I decided to revive an old Heathkit IT-28...

Dan Koellen AI6XG

Jan 25, 20211 min read

1,155 views

0 comments

Mount Rose W7N/WC-001 Activation

Lake Tahoe and Tamarack Peak From Mount Rose Summit Trip Summary Distance: ~ 4.9 mi one way Transport: Hiking Elevation Gain: ~1800...

Dan Koellen AI6XG

Dec 15, 20202 min read

307 views

2 comments

Tamarack Peak W7N/WC-003 Activation

Lake Tahoe From Tamarack Peak Summit Trip Summary Distance: ~ 1.3 mi one way Transport: Hiking Elevation Gain: ~960 feet Time: ~ 0.75...

Dan Koellen AI6XG

Dec 13, 20202 min read

225 views

2 comments

Mount Houghton W7N/WC-002 Activation

Operating Position on Mount Houghton, Mount Rose W7N/WC-001 in Background Summit Trip Summary Distance: ~ 4.8 mi one way Transport: ...

Dan Koellen AI6XG

Dec 10, 20203 min read

132 views

2 comments

Scott Peak W6/NS-153 Activation

Operating Position on Scott Peak Summit Trip Summary Distance: ~ 4.2 mi one way Transport: Hiking Elevation Gain: ~1700 feet Time: ~2...

Dan Koellen AI6XG

Dec 3, 20202 min read

137 views

2 comments

Granite Chief W6/NS-115 Activation

Operating Position on Granite Chief Summit Trip Summary Distance: ~ 4.6 mi one way Transport: Hiking Elevation Gain: 2748 feet Time:...

Dan Koellen AI6XG

Nov 29, 20205 min read

84 views

2 comments

Wishing You a Very Random Christmas

Being the holiday season I decided to post this article from the December 2014 issue of Nuts & Volts magazine www.nutsvolts.com that I...

Dan Koellen AI6XG

Nov 23, 20201 min read

95 views

2 comments

Trapped 20/30/40 Meter EFHW Antenna

An End Fed Half Wave (EFHW) antenna for operation on 20, 30 and 40 meters was built for SOTA operation. By using traps, the antenna...

Dan Koellen AI6XG

Oct 4, 20208 min read

11,351 views

2 comments

Big Font Clock Update: Dimmer-Interface PCB and Setup Instructions.

A prior post described the development and build of a clock to display time and date for UTC and Local. The clock characters are large,...

Dan Koellen AI6XG

Jun 29, 20207 min read

222 views

2 comments

End Fed Half Wave Antennas: More About the Primary Capacitor

I recently posted a blog claiming that a capacitor in the primary of the matching transformer is not needed for end fed half wave (EFHW)...

Dan Koellen AI6XG

Jun 6, 20204 min read

9,587 views

7 comments

End Fed Half Wave Antennas: Is a Primary Capacitor Really Needed?

In my research on End Fed Half Wave (EFHW) antennas I found that nearly all have a capacitor in the primary (rig) side of the transformer....

Dan Koellen AI6XG

May 27, 20203 min read

24,223 views

4 comments

Auto Run for your Raspberry Pi - how to have your Rpi boot up in the desired configuration.

The Raspberry Pi (Rpi) is a great single board computer (SBC) that can be used in many projects and comes in different configurations. I...

Dan Koellen AI6XG

Apr 5, 20203 min read

103 views

2 comments

Big Font Clock - Relieve for Old Eyes

Recently the Maker Space that I frequent received a number of 4 line 40 character (4 x 40) LCD displays. They asked me to figure out how...

Dan Koellen AI6XG

Feb 9, 20209 min read

970 views

2 comments

Castle Peak W6/SN-038 Activation

Operating Position on Castle Peak Looking Southwest Summit Trip Summary Distance: ~ 3.5 mi one way Transport: Hiking Elevation Gain: ...

Dan Koellen AI6XG

Jan 12, 20203 min read

162 views

2 comments

Sand Ridge W6/NS-155 Activation

Operating Position Looking South From Sand Ridge Summit Trip Summary Distance: ~ 6.5 mi one way Transport: Hiking Elevation Gain: 1200...

Dan Koellen AI6XG

Jan 12, 20204 min read

112 views

2 comments

Mount Lincoln W6/NS-149 Activation

Looking east from Mt. Lincoln, Tinker Knob W6/NS-121 is hiding behind Anderson Peak Summit Trip Summary Distance: ~ 3 mi one way...

Dan Koellen AI6XG

Jan 11, 20202 min read

118 views

2 comments

Signal Hill (7751) W6/NS-393 Activation

Looking east from Signal Hill, Donner Lake is in the background and Lake Angela in the foreground Summit Trip Summary Distance: ~ 2 mi...

Dan Koellen AI6XG

Jan 11, 20202 min read

219 views

2 comments

Tinker Knob W6/NS-121 Activation

Summit Trip Summary Distance: 7.2 mi one way Transport: Hiking Elevation Gain: 1870 feet Time: ~3.5 hours one way Route: Via Pacific...

Dan Koellen AI6XG

Jan 9, 20203 min read

100 views

2 comments

How to do a SOTA Activation

SOTA activations are challenging and with risk, be sure you are experienced in hiking, navigation and survival skills.

Dan Koellen AI6XG

Jan 6, 20206 min read

714 views

2 comments

SOTA - What is it? Why I do it

What is SOTA? SOTA, or Summits On The Air, is basically an activity where ham radio operators take their radio equipment to a hill or...

Dan Koellen AI6XG

Dec 23, 20193 min read

345 views

2 comments