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Elecraft K3 vs. ICOM IC-781

vs. Kenwood TS-850:

Comparative Measurements and Experience

Version 1.1

Matthias Jelen, DK4YJ

Ben Büttner, DL6RAI

Toby Deinhardt, DD5FZ

January 21, 2008

1 Introduction

by Matthias Jelen, DK4YJ

Toby, DD5FZ, was kind enough to lend me his brand new K3 over Christmas. Which gave me time to play

around with the rig. The ﬁrst impression of the radio’s acoustic properties at DK0MN (our club station) and

in my own shack were very positive. Because Elecraft is cocky enough to assert that the K3 is as good,

if not better, than Japanese rigs in the 10ke category, I wanted to ﬁnd out how accurate their claims are.

Unfortunately I did not have a 10,000 e rig, so I used my father’s (DL3MII) IC-781 as a reference. The

IC-781 is not the newest, but, for good reasons, its RX enjoys a good reputation.

I measured the MDS, IP3 using the same methods as the ARRL uses for their tests. I also did a (kind of)

relative phase noise measurement. All measurements were performed at 14.1 MHz. The other bands would

also have been interesting, but the ARRL will surely be doing this soon.

The ARRL measures IP

as follows:

1. A "Two Tone Signal" source is connected to the RX.

2. Each signal is adjusted so that each signal causes the s-meter to display S5. These levels are used the

reference level (P

ref

3. The RX is tuned to the frequency where the expected intermodulation product should be.

4. The level of both signals is raised until the intermodulation product reaches S5. This level is P

imd

The IP

is calculated using the following:

−P

ref

+ 3P

imd

1 2 3 4 5 6 ... 11 12

Summary of Contents

Page 1 - Elecraft K3 vs. ICOM IC-781

Elecraft K3 vs. ICOM IC-781vs. Kenwood TS-850:Comparative Measurements and ExperienceVersion 1.1Matthias Jelen, DK4YJBen Büttner, DL6RAIToby Deinhardt

Page 2 - 2 Results

Now, I knew I had seen the fortune cookie with TXCO board, and it was where I had left it, but, that’s funny,no TXCO in the bag, only the board.**PANI

Page 3 - 3 Conclusions

5.5 K3 Praise• The radio is easy to use and if you come from a K2, the tap and hold philosophy and the radio itself arealmost instantly understandable

Page 4 - 4 Practical Experience

Wayne: I’m surprised that this occured. Recent ﬁrmware revisions should have cleaned up this behavior ingeneral. There are still some issues remaining

Page 5 - 4.2 The Rear

S5 is, of course, an arbitrary reference level and any other level could be used as Pref. My experience is thatthe S5 method tends to be somewhat more

Page 6 - 4.5 RTTY

0 20 40 60 80 100−15−10−505101520253035IP3 vs. TrägerabstandAbstand der Signale [kHz]IP3 [dBm] 781 (oben)781 (unten)K3 (oben)K3 (unten)0 20 40 60 80

Page 7 - 4.7 Resumè

4 Practical Experienceby Ben Büttner, DL6RAIToby also lent me his new rig for about a fortnight during the ﬁrst days of 2008. I used this chance to sp

Page 8 - 5 The Proud Owner

The continuously adjustable IF ﬁltering (shift/width) with automatic rooﬁng ﬁlter switching is the hit, duringcontest operations, for ﬁghting QRM or ﬁ

Page 9 - 5.3 The K3 Build

• For the RX antenna and transverter: BNC, a very good choice, experience has shown RCA a poor choicefor RF.The RS-232 interface for the transceiver c

Page 10 - 5.4 K3 Gripes

4.6 Antenna TunerI tested the K3’s tuner with my puny 2x 13m dipole and 300 Ω twinline feeder on all (German) bands except160m. The tuner in the TS-85

Page 11 - 6 Elecraft says

5 The Proud Ownerby Toby Deinhardt, DD5FZ5.1 IntroductionI would like to use this chance to thank Ben and Matthias for the time and effort it took to

Page 12 - References

The ﬁnal conﬁguration will see the KBPF3 installed on the secondary RX and I will move the 6 kHz ﬁlterfrom the main to the secondary receiver, allowin