Dan Koellen AI6XG
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
top of page
Dan Koellen AI6XG
- May 9
- 9 min
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...
220 views0 comments
Dan Koellen AI6XG
- Jul 18, 2023
- 11 min
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
682 views0 comments
Dan Koellen AI6XG
- May 2, 2023
- 6 min
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...
319 views0 comments
Dan Koellen AI6XG
- May 2, 2023
- 6 min
QRP Tube: T/R Switch and QCX Interface and Modification
A Modified QCX and TR Switch for Vacuum Tube SOTA transmitter
268 views0 comments
Dan Koellen AI6XG
- May 2, 2023
- 15 min
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...
421 views0 comments
Dan Koellen AI6XG
- May 2, 2023
- 5 min
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.
1,368 views0 comments
Dan Koellen AI6XG
- Feb 28, 2023
- 5 min
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...
2,125 views0 comments
Dan Koellen AI6XG
- Jun 17, 2022
- 5 min
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.
1,415 views0 comments
Dan Koellen AI6XG
- May 16, 2022
- 6 min
Reactive Component Measurement With the NanoVNA
Exploration of using the nanoVNA to measure inductance and capacitance at frequency of use.
2,930 views0 comments
Dan Koellen AI6XG
- Mar 2, 2022
- 11 min
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...
2,029 views0 comments
Dan Koellen AI6XG
- Jul 30, 2021
- 2 min
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...
96 views2 comments
Dan Koellen AI6XG
- Jul 20, 2021
- 9 min
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...
658 views0 comments
Dan Koellen AI6XG
- Jun 16, 2021
- 13 min
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...
1,790 views3 comments
Dan Koellen AI6XG
- Apr 26, 2021
- 3 min
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.
80 views0 comments
Dan Koellen AI6XG
- Apr 25, 2021
- 9 min
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.
328 views0 comments
Dan Koellen AI6XG
- Jan 25, 2021
- 2 min
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...
217 views1 comment
Dan Koellen AI6XG
- Jan 25, 2021
- 1 min
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...
1,037 views0 comments
Dan Koellen AI6XG
- Dec 15, 2020
- 2 min
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...
294 views0 comments
Dan Koellen AI6XG
- Dec 13, 2020
- 2 min
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...
189 views0 comments
bottom of page