Should contest rules allow and act upon 599K QRM reports?

Sunday, 1 December 2013

SUCCI-R Rig control, CW and PTT

Bought one of these as my Microham cw keyer is a bit bulky and expensive for portable operation. I planned to use my K2 from the car for CQWW CW 2013 using the call MM3T. I have in the past experienced QRM from using USB to serial cables. The SUCCI-R uses a noise filter on the serial link and opto-isolators on the CW and PTT lines to keep noise to a minimum. Cables are simple to make up (same as cw keyer). My location was picked for it's proximity to the sea and height above it. Being very remote I had no QRM so could give the SUCCI-R a good hammering in the contest. After 10 hours of contesting with 400w and a vertical antenna right next to the car, I realised that the SUCCI-R had just worked with no noise, lock ups, corrupted keying or odd buffering that I have experienced with other interfaces. Just brilliant and I can highly recommend it. It's very well put together and required no extra driver Polava when connected to a windows 7 laptop. Work seamlessly with Wintest contest logging software.

Saturday, 17 August 2013


A big improvement recently by Elecraft. A hardware fix on the KXFL3 dual pass-band roofing filter has removed the tuning noise clearly audible above 21MHz. The loud brrrrrrrrrrrrrrp! on moving the VFO dial has now gone! Hats off to Elecraft for finding this problem and publishing the fix. However, I did have the disappointment of having to put up with this problem for 6 months and would like to vent my frustrations. I had assigned the KX3 to the bucket, but now I'm starting to play with it again. How did it ever leave the factory like this? Surely during IVVQ testing they turned the VFO on a fully loaded KX3 above 21MHz? However, not every user noticed this problem, going by the number of 5/5 scores on EHAM. My only salvation during this period was a German ham DL7VDX (far enough away from the USA mojo to critise) who posted evidence of this fault on youtube (thanks Ron by the way). ( I could hear my KX3 tuning noise on 10m above the normal 51-2 background noise that a 3 element monoband yagi provides to the rx. Does this mean that quality control at Elecraft is variable to say the least? Maybe my KX3 was a Friday afternoon beer time pup. But lets get back to the fix. Initially we all had to put up with nonsense suggestions and menu fixes like enabling the 8KHz rx shift (which disabled the KXFL3) or enabling the VFO NR (to try to hide the problem in firmware). This reminds me of similar ridiculus suggestions on how to fix the speaker problem, like "just change the AGC threshold to 4 and the rumbling speaker problem goes away!".... please, if you don't know what AGC threshold does, don't open your mouth :-). Anyway I digress, the actual fault brings into question the PCB layout quality at Elecraft. The fix was in hardware and consisted of 3 pins being cut off the KXFL3 connector. These pins formed a serial link to a surplus EEPROM on the KXFL3 board. Altough these serial links seem innocuous in terms of operational frequency (100KHz->400KHz) they contain harmonics (due to clock and data pulse edges) which stretch up into the HF domain. PCB layout of these links needs special attention to ground return signal paths to avoid these harmonics straying from directly below the links (good design) and instead going into other sensitive circuits (bad design). All that is required to prevent this is an uninterrupted ground plane directly below the serial link. I suspect that the Elecraft's modular architecture is a victim of it's own success here, as passing these signals from board to board presents signal integrity problems manifesting in a brrrrrrrrrrp! out the speaker! There are other rx problems apparent only on tuning that disappear when you stop turning the VFO. No one else seems to have noticed them yet, but if you are a cw operator and stop on weak signals in a busy band you'll know what I'm talking about. Opposite sideband supression is suspect coupled with heavy firmware stitching to hide it. I'm still uncertain wether I'll ever be able to use this radio in favour of my K2. I'd like to end this rant on a high note as although I'm moaning here, there is no company out there that comes closer to understanding the customers desires than Elecraft in terms of amateur radio equipment. I'm truely grateful to Elecraft for the K2 and the K3 I own and hopefully in time the KX3 also.

Saturday, 5 January 2013

Innovantennas LFA2 3 element yagi for 10m

During the christmas break I ordered the above antenna. The plan was to build and errect it during the break weather permitting. Unfortunately for Justin at innovantennas, this meant dealing with an order at short notice just before christmas. Justin said he'd do his best to get it to me over the christmas holidays and sure enough a box arrived on the 27th by courier. Unfortunately there were no instructions in the box, but the LFA2 is so simple in construction I couldn't go wrong. The materials used are high quality and all the holes are pre-drilled and in perfect alignment. The antenna went together quickly, but it became obvious that there were 4 poles missing from the loop element. I e-mailed Justin as soon as I realised and luckily Justin was still working. Justin asked for a photo of the antenna so he could assertain which parts were missing and very quickly agreed the missing parts. 3 days passed and again the courier arrived with another box that completed the necessary parts.

I have to thank Justin for such excellent service as although the initial order was incomplete it was sorted out proffessionally and quickly and all this over christmas and new year holidays!
Whilst waiting for the missing parts I did 2 things:
1) Decided on a feeding arrangement and built a coaxial balanced feed out of 2 lengths of rg213 and a three way tee piece connector.
2) Profiled my original cushcraft ten-3 (3 ele 10m yagi) with a local ham 4 miles away.
The result from the original antenna:
Signal strengths to local station
towards, s8
180 degrees away, s2+
Noise towards the neighbours houses
towards, s4+
180 degrees away, s1+

I removed the Cushcraft ten-3 and mounted the LFA2 using the same pole and coax but with the addition of the coaxial balanced feed arrangement in-line.

The result from the LFA2 antenna:
Signal strengths to local station
towards, s8
180 degrees away, s2
Noise towards the neighbours houses
towards, s2+
180 degrees away, s0+

I'm not sure the noise figures with regards the neighbouring houses can be relied upon as this is dependant on what they are doing but the noise definately seemed down.

So all in all I'm happy:

pros : lower noise, good materials/construction
cons : the balance point for this antenna occurs at the driven element position meaning that when mounting it to a stub mast the weight has to be offset which can cause the end to droop or raise accordingly.