JL3AMK since 1983

JL3AMK's Web Site
"May the Morse be with you"
http://www.jl3amk.org/ or http://www.jl3amk.net/


Park Bench Portable with Elecraft KX1



Welcome to my web site. Let me introduce myself.

My name is Harry. I was born in February 1969 and I have been a radio amateur since 1983. It was summer when I was a junior high school student, I got a no-code (4th class) operator's license, and got a station license in fall. I was 14 years old. I got a Morse code (3rd class) operator's license when I was a high school student in spring 1985, age of 16. After that, I had enjoyed DXCC hunting and contesting, especially on 15m/10m CW. The propagations were not so good because it was around the bottom of the Solar Cycle 21, but the weak signals from Europe on 15-meter CW were exciting me. Around 1990, Sunspot Numbers were increasing, but I was not excited because so many stations were on the band and they were so strong. In addition to that, I found employment and moved, so almost QRT on HF until 1997. I had enjoyed amateur packet radio on 70cm/23cm during 1989 and 1994, and portable operation on 6m CW/SSB during summer in 1994 and 1995. I sometimes QRV'd on 12-meter CW with long-wire from 1997 to 2000.

In 2001, the new century, I bought an FT-817, small portable QRP transceiver from YAESU - Vertex Standard, and several telescopic antennas. I live in the apartment so I have been on the air from somewhere; a park, a mountain, or other places. Its RF output power was not big, maximum only five watts. I was very excited when I could contact with overseas stations. For example, I could QSO with KH2/Guam, with only 500 milliwatts, it was about 5,000 kilometers per 1 watt. T8/Belau, also 500mW, it's about 6,000km/W. The best 'km/W' was with V6/Micronesia, 500mW again, it's about 7,000km/W! It's fantastic! I might be with the FORCE! If I had a big antenna, I won't be excited, but my antenna was just a small telescopic whip. The most exciting QSO was with W3/Pennsylvania in fall 2002. It's distant over 11,000 kilometters between Osaka and Penn! At that time, power was five watts, so it was about 2,000km/W, but the propagations were over the North Pole. Another U.S. station I had worked was in W7/Washington, it was about 9,200km, using 1 watt into a dipole antenna on a tripod. These QSO's were had on 17m/15m/12m bands CW.

I know a pleasure for building kits nowadays. I built Small Wonder Labs' Rock-Mite 20 in 2003, Elecraft's KX1 in 2004, and again Elecraft's K1 in 2005. From late 2006 to early 2007, I built Elecraft's K2. I'm currently active on CW on HF high bands with my K2.


--- May 2015 ---

I have updated my antenna system for home operation, DIAMOND HF40FXW and HF20FX mobile whip antennas with counterposes (5 radial cables). I usually QRP with QRP and sometimes QRV with ICOM IC-706 (running 100 watts). I hope to see you on 40-meter or 20-meter CW.


--- 2016 ---

Currently I don't have Elecraft KX1, K1 and K2, but have a KX3 and a KX2. I have replaced ICOM IC-706 with KENWOOD TS-480SAT. The antenna, DIAMOND HF20FX has also been replaced with COMET UHV-6. I can QRV on 40-meter, 30-meter, 10-meter and 6-meter bands without ATU, and 20-meter thru 12-meter with ATU.

Elecraft K1 Modifications


When the strong signals came into my receiver, I was very surprised because of the loud sound. So I changed some capacitor on the RF Board of my K1.

K1_AGC_Notes (from Elecraft Reflector)
[Elecraft] K1 revisited

LCD Backlight

Elecraft now presents K1BKLTKIT, the LCD backlight mod kit. I put it into my K1. So I can operate even if it is dark. Not so bright, but easy to read.

160m Band Filter Board

The K1 covers 80m to 15m (4-band or 2-band), but Don, W3FPR modified two-band module to 160m. My K1 can be on 160m running 9 watts RF output.

[Elecraft] 160M K1 band option (From: Don Wilhelm W3FPR Date: Tue, 10 Feb 2004 22:20:20 -0500)

BFO Changed to USB

The BFO of K1 is LSB but I usually use 17m/15m filter board, so I changed the BFO to USB from LSB by removing and jumpering RFC1 on the RF Board. I can listen to the SSB (USB) stations.

Special Thanks:
A staff of Elecraft support team told me how to modify. MNI TNX.

VFO Spread Out

I added a 68pF capacitor in parallel with C2 (120pF) on the RF board to make the VFO range spread out because I want to listen to SSB QSOs. VFO covers about 267kHz, but it is difficult to tune.

I removed a cap. because it was so critical to tune.

Power Increased

The output power of my K1 was four watts on 15 meters, so I added a 0.001uF capacitor (as a bypass) in parallel with R30 on the RF board.

160m: 10W (not changed)
80m: 10W (not changed)
17m: 7W (from 6W)
15m: 7W (from 4W)

12m/10m Modification

Special Thanks to Stephanie, VA3UXB
for her suggestions on component values


Component Values

Ref. Designators
Band 1
Band 2
12 meters
10 meters
C1, C5
C6, C10
100 (or 82) pF
C2, C4
C7, C9
C11, C15
C16, C20
270 (or 220) pF
C12, C14
C17, C19
C21, C23
C24, C26
L9, L10
(T37-6 core)
L11, L12
(T37-6 core)
8 turns
8 turns


Additional mods I did were almost same as Stephanie's:

In addition to above mods, I added a 0.001uF capacitor in parallel with R30 on the RF board to increase the RF output power.

ATTN: VFO range must be 150kHz or more because K1 covers 12-meter band starting 24.800MHz, but this band begins from 24.890MHz.

RF Output Power

Band Output
24MHz 7 watts
28MHz 4 watts


[Elecraft] K1 on 10 meters: helpful advice (by Wayne Burdick N6KR @ Mon Dec 26 14:44:01 EST 2005)
[Elecraft] 10 meters on K1 - component values (by Stephanie Maks VA3UXB @ Sun Jan 1 12:57:13 EST 2006)

Additional Info: [Elecraft] 4-band K1 module covering 10-20 meters? Also: less-expensive 10/12 m crystals (by Wayne Burdick N6KR @ Sat Jan 7 14:13:04 EST 2006)


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