23 October 2015

A corrected version of QST's KSYN3A in K3 review


there is the link for corrected version of QST's KSYN3A board review which is replacing the erroneous TX phase noise plot in their last QST article:


Figures 10 and 11 have been updated by the ARRL to show the KSYN3A's actual transmit phase noise. As you can see, relative to the original synth, the KSYN3A has far lower noise at close offsets (toward the left end of the graph), and nearly identical noise at wider offsets (toward the right).

As Wayne, N6KR mentioned previously, this is a *transmit* phase noise plot. Phase noise is even lower right at the output of the synth module itself, accounting for the KSYN3A's outstanding RMDR (reciprocal mixing dynamic range, which applies to receive mode).

There is also explanation of their mistake in LF bands performance (500kHz/137kHz) measurement due to lack of proper modification on tested K3!

Thanks to Wayne, N6KR for sharing the link...

Hope it helps,

73 - Petr, OK1RP

20 October 2015

TMP-K01X-A1 connectors and cables for Elecraft K3


as it was hard to find the TMP connectors for making the calibration  of K3 in Czech even in nearest Europe in the past I tried to looking for distributor world-wide. I realized that some sales contacts does not work or links fails so I sumarized the actual links and informations again. 

BTW: What is the TMP connector or even TMP cable in K3 transceiver...?

It is one of the cables used for the second receiver module KRX3.
If you have the receiver module then you can start reading at page 22 of the installation and operation manual (assuming Rev. B of manual). Also it is used for KSYN3A, KAT3 to AUX and other modules inside of K3. You are not aware if you ordered K3-F (factory assembled) unit :) but for all those assembled their K3s by themself it is very known...
The TMP cable 12" is the Elecraft part: #E850339.

For all who would like to make coaxial cable for calibration of K3 instead of some temporary solution there are useful informations I guess:

Type: TMP-K01X-A1 connector 50ohms for RG-174/U coaxial cable type

Assembly Standard:


Quick assembly reference:

Sales links:

on eBay:




or here:


Hand-crimp-tool to buy:

The tips and hints discussed here:

The most important is to be ensured that the center pin is in it's socket properly, not bended, not misaligned during installation and as Guy, K2AV is saying..."The outer shell of the TMP plug can be connected without being fully inserted into the TMP connector. This can result in an intermittent on the center conductor that comes and goes with temperature change, or breathing hard, or changes in phases of the moon. The little flanges on the TMP plug should be nearly up to the TMP connector shell when fully inserted."

When it is in use I am recommending to check time to time (you do not need to do it before "each flight" :) the connectors if all of them are correctly inserted and if there is no rust, corrosion or silver coated TMP connectors are not becoming black...

Hope it helps.

73 - Petr, OK1RP

QST Review of KSYN3A synth in K3 has erroneous TX phase noise plot

Hi all,

although I am not re-posting the articles from the other sources to my blog over here in that case I am doing it as it is very important for many of Elecraft K3 users.

In order to better understaning the situation about the KSYN3A boards and parameters after the upgrade and for explaining the QST Review results there is the latest statement from Wayne, N6KR...

"Hi all,

You may have noticed that QST recently reviewed the K3's performance before/after swapping in a new KSYN3A synthesizer. While the review text was accurate (and complimentary), there was a significant error in the KSYN3A TX phase noise plot (Figure 10). This error made it appear as if the original synthesizer had lower (better) wide-spaced phase noise than the KSYN3A (starting where the plot lines cross), which is not the case.

We should have caught this ourselves before the article went to print. We greatly appreciated the League's efforts to determine the source of error -- equipment setup -- and re-test. The digital-print version of QST will be corrected, and a correction will also appear in the December QST.

The ARRL sent us the revised TX phase noise plot for the K3+KSYN3A that they tested. You can see it here: 

In addition they're testing a K3S. Its TX phase noise plot looks as good or slightly better: 

These plots (used with permission) were for 20 meters, and are also representative of the other bands, including 6 meters. The bottom line is that the K3S, or a K3 with a KSYN3A, has extremely low phase noise at both close and narrow spacings. In the case of narrow spacings, the new synth also significantly improves the RMDR (reciprocal mixing dynamic range) over the original, as described in the article.

Note that the above plots show *transmit* phase noise. In receive mode, phase noise with the new synth is even lower, especially at close spacings (under 3 kHz from the carrier).

There's one other measurement in the QST review that needs a disclaimer. As you may know, the KSYN3A allows the K3 (or K3S) to be tuned down to as low as 100 kHz, thus including the 137 kHz band. The review showed an MDS of -44 dBm at this frequency, while in fact it is more like -115 dBm. It appears that the K3 under test didn't have the RF board modification required, or the modified KBPF3A filter module.


I hope it helps and it will clarify more the results and measurement done by labs reviewed in QST magazine.

73 - Petr, OK1RP