Elecraft KX3. Experiences from the field.

This page will be an ongoing blog, updated from time to time documenting my experiences with the KX3.

My KX3 #4625 was bought as a kit and delivered to VK3 in August 2013. The Australian dollar was 92 cents to the USD then! The purchase was assisted with the sale of some underused equipment – my original FT-747 and HR-2510. Even so, it was difficult to justify the expense. In the end, I thought I would get greater benefit with a modern state of the art radio that did not require additional equipment such as tuners to operate as per my intentions.

The kit form was a bit cheaper but also gave me a project plus mean’t I would have a better knowledge of the radios internals. The kit came with the works. Real time clock / charger, roofing filter, antenna tuner, microphone and paddle. The instructions were pretty good and the construction went pretty much to plan with the exception of being one screw short. Fortunately I could use a spare from the parts not required due to me fitting the real time clock module.
It was with trepidation that I installed some internal batteries and turned it on followed by relief that it actually worked and no smoke came out.

RF and Tuner boards

Close up of the tuner board

With anything new, it takes time and experimentation to get the best out of it. Fred Cady’s (KE7X) book on the KX3 gave some good insight as to setting up audio filtering and the roofing filters. I trialled it with my portable antenna at the local primary school prior to the first activation at the local summit Mt. Dandenong.

CW is a natural with the KX3. Default filter settings are in the mid range. The CW RX decode appears to work quite well but is dependent on good code

being received. The display is bright and big

Roofing filters LHS, tuner board fitted. PA centre

enough to read without the back lighting on although the shortage of character space means a short buffer for what is received to remain visible. My first experience with a paddle took little time to get used to and my sending improved considerably within a short space of time. This prompted me to purchase a Vibroplex paddle for the home station.
On the RX side, the quasi stereo with headphones is great. The RX via the internal speaker is average and can distort with loud and strong signals.

The christmas / new year of 2013/14 is when I had my first issue. I found my CW sending to be erratic with the radio not sending what was being keyed in. I discovered the CW paddle pins were loose and infact had separated from the solder connections on the circuit board. There appeared to be minimal solder and the joints were dry. I fixed this by placing the pins into the paddle, fitting the paddle to the radio and then soldering them into position. Elecraft were notified of my problem and that I had fixed it.

With hindsight, another unrelated problem began while I had the radio operational from the MDRC hamfest in 2014. The WX was drizzly and I has it under a bucket whilst I was on the BBQ. I noticed that it was TXing without the mic button or TX button being depressed. Un-plugging the mic stopped this. Thinking it was a condensation issue, I pulled the covers of the radio and mic and dried everything out. The problem resolved?
Well, not quite. I sporadically experienced the same fault when operating in similar conditions and earlier this year from Mt. Macedon (2015) it became almost unworkable. I detected the problem being related to the position of the mic cord and planned to investigate once home. It was interesting to chat with Gerard VK2IO – who by chance had experienced the exact same problem.
The issue is with what I believe to be a defect with the cord. The insulation of the internal cabling being missing in places and causing a short circuit. The fix was to shorten the cord and resolder the connections. The insulation was not just on the green wire as shown which was at the end of the double sheathing but also on others further down once the sheathing was removed.

With the proof of time, the mic problem is now all fixed. To be truthful, I was not too impressed and surprised not to read of similar problems on the KX3 Yahoo group site!
Anyway, back to 2014:
My KX3 went to France and performed flawlessly. I used it with an Alex Loop but also on occasion with two short bits of wire set up as a basic doublet without spreaders or insulators. Worked into Corsica on 30m cw from the Nivernais Canal. The tuner is amazing in what it can do with little apparent losses. The tuner will also memorise previous settings and can be set up to provide instant tuning with frequency changes across all bands.

Next stop  is October 2014 and the 2 metre module. I was not sure if I really needed it but what the heck! An opportunity came to be part of a group order and thus limit the postage.
The module comes as a kit and the instructions need to be followed to the letter. Routing of the cables is very critical. The issue that I had was the location of L40 and L43 on the main RF board. Both these toroidal transformers were way too close to the 2 metre SMA connector and as per instruction, required to be pushed out of the way to clear the connector. I managed to break the core of L40 as it was physically in the way of the SMA connector and required too much force to move. Re-soldering would have been a better option. A replacement was sent out by Elecraft at no charge but was fiddly to fit.
Now all installed and the software updated, I tried it out in the back yard and all was good. That was that, no real need to use 2 metres, seeing that I had an FM hand held that was more convenient to use.

September 2015
With a 5 summit activation planned and HF propagation of late being erratic, I thought as a back up I would use 2 metres SSB. Best to check it out at home and make sure I had all the patch leads and the like plus I have a 30 watt amplifier.

Upperside of 2 metre module. Shield removed.

Hard to see by the photo but, as per instructions, the shield must be fitted in the correct orientation otherwise it will short circuit the PA.
First I noticed the SMA connector was loose. Not a simple fix as the nut on the inside was very loose and to adjust required the removal of the 2 metre and tuner modules.
Next, when on air, all seemed OK and then no RF output on the meter. Checked dummy load, antenna, power meter, leads, soft ware. Further invesiigation showed some RF output but at extremely close range only – a metre or so. PA mosfet failed. Being still under warranty, a replacement module was sent out from Elecraft and fitted. Problem solved. I have since had a nunber of good 2 meter SSB and CW contacts using a 4 element yagi. Reports on the last activation was that I was 400hz high in frequenct. Must check this out. Could it be a temperature issue as the radio was in full sun and it was warm to hot?

Underside of 2 metre module showing PA mosfet

A side issue with the 2 meter module PA fault was this:
In taking the covers and modules out on multiple occasions, I must have overtightened one the grub screws. Maybe the much cooled conditions on Mt. Matlock had something to do with it but on moving the RHS leg to sit the radio up, the screw sheared off. This left the leg and screw remnants dangling within close proximity of internal circuitry. The only method available to rectify this was to prise the opening in the radio open with a large screw driver. I am still one grub screw short but swapped it over with one that does not have a leg attached. I no longer raise the radio via its legs.

I have the Side KX panels and cover fitted. I feel these greatly assist in safe transportation and storage of this radio. If there is one concern with the radio, it is with the radios robustness. I feel that more care than such with an FT-817 is required, particularly in damp or dusty conditions.

01/01/2017.

Further microphone issues. Same issue as before with the cord supplied with the microphone being defective in its construction. I think folding the cord to get the microphone into the KX3 lunch box carry case could be compounding the issue. Microphone repaired again and thus far, 6 months latter all is good. This is just as well because the key let me down big time today.

Modified KXPD3

The Elecraft KXPD3 paddle is, in my opinion, also a defective design. The dots and dashes are formed by their respective paddles making contact with fixed terminals mounted on the KXPD3 circuit board. The paddle forms the ground return circuit.
The problem is that the paddle is not adequately grounded, relying upon the screw terminals into the radio and, as where I came to grief today, by the pins that the paddle arms pivot on. With a bit of wear due to normal use plus possibly having recently got wet, the ground return on the LHS dot paddle just did not work and the dashes seemed to have a time delay.
The solution is to hard wire both paddle arms to ground. I did this using some 15 amp tinned fuse wire, attached via the head of the tension spring screws and soldered to the ground pin of the paddle connector.
Far from impressed with this fault that has been experienced by numerous other CW operators. My advice, if you have the KXPD3 is to make the modification before you are let down.

More to follow? Tony VK3CAT