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Park Bench Portable with Elecraft KX1

Created: October 2002
Updated: August 2019


Contents


Elecraft K1 Modifications

ATTN: This content will not be updated because I do not have a K1 anymore.



AGC

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.

References:
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.

Reference:
[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.

p.s.
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

Parts

Component Values

Ref. Designators
Qty.
Components
Band 1
(24.8MHz)
Band 2
(28.0MHz)
12 meters
(24MHz)
10 meters
(28MHz)
C1, C5
C6, C10
2
100 (or 82) pF
82pF
C2, C4
C7, C9
2
47pF
47pF
C3
C8
1
1pF
1pF
C11, C15
C16, C20
2
270 (or 220) pF
220pF
C12, C14
C17, C19
2
33pF
33pF
C13
C18
1
2pF
2pF
C21, C23
C24, C26
2
68pF
68pF
C22
C25
1
150pF
150pF
L9, L10
(T37-6 core)
(yellow)
L11, L12
(T37-6 core)
(yellow)
2
0.26uH
8 turns
(16cm)
0.26uH
8 turns
(16cm)
X1
X2
1
32.8000MHz
(fundamental)
36.0000MHz
(fundamental)

Mods

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

References

[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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