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

Saturday, 31 October 2009

Elecraft K3 filter offset measurement (8 pole, 400Hz)

Just had a look at my 8 pole 400Hz filter with it set to kick in at DSP BW 900Hz to keep any DSP effects down and the AGC set to off. Did the measurement (using my FT1000MP MkV providing the sig into dummy load with wire to K3 antenna port wrapped round it giving S9 on the K3 meter. The MP has the high freq stab option fitted).
Using the dBV meter on the Elecraft display and resetting it to 0dBV on each measurement by reselecting it on the menu.

Initial results for -6dB points: -265Hz / +198Hz (meaning offset too high by approx 30Hz within 463Hz)

Adjusted 400Hz filter offset value to -0.03

Final results for -6dB points: -235Hz / +228Hz (meaning offset too high by approx 3Hz within 463Hz)

Note that the filter bandwidth was measured dead on 463Hz on both measurements giving me some indication of measurement accuracy.

Monday, 26 October 2009

MM3T CQWW Phone 09

It's the day after CQWW phone 09 and I was so impressed by the K3's performance during the contest, I just needed to share.

I'm not a keen SSB operator, but I like to give some points away. The main thing I learnt this contest was that LO-CUT-HI rocks in SSB! I'd been putting up with horrendous QRM trying to work DX buried between big EU stations. I was using the WIDTH control with not much improvement apparent, when in desperation I decided to try and see if I could winkle the DX out with SHIFT / LO-CUT-HI. The result raised my eyebrows is was so good. I didn't realise that intelligibility could be so good at such narrow (shifted) bandwidths. It made me regret choosing the 2.1KHz instead of the 1.8KHz roofing filter.

On another subject,

This contest the following stations decided to start up on top of me when it was impossible to miss me:
They all suffered from "selective deafness" on a busy 40m.

Out the three, DC4A was the worst, he started up with no QRL at 59+40dB exactly on my frequency. I recon his chosen technique is to pick the least QRM freq, then leave the voice keyer on continuous loop whilst leaving to make himself a cup of tea. When he comes back the QRM he has caused has driven away any occupant (as it's pointless trying to reason with a recording). During the time he QRM'd me, he made no contacts. I had to comply and QSY or lose points being stubborn.

Anyway for the first time it annoyed me so much I nearly gave in with frustration. I went downstairs and had a break and before long was back on 40m doing hunt and pounce.

Another couple of times stations started up impossibly close to me and even though I caught them immediately with "please QSY the frequency is in use" they carried on regardless "selected deafness" style. In one case the station complied to my plea only to move 300Hz further away :-). I think tiredness really comes through in these eventualities and it's best not to be provolked by their stupidity and just to take a break (even though they have just ruined a run into the states after a spot).

Saturday, 3 October 2009

Elecraft K3 Subreceiver (KRX3)

I collected the KRX3 from our local Parcel Farce depot and after 3 nights (2 hour sessions), had it in the K3 and working. The build went very smoothly with all parts present and some extra screws and washers for good measure. Instructions were well written and left nothing to experimentation.

However, I did make one silly mistake where I put the filters in the wrong positions (L-R not R-L) and ended up having to take the KRX3 back out and reposition them. It took me an hour of head scratching and foul language till I realised my mistake :-) (the KRX3 filters are unusually numbered from 5-1 (L to R) so your widest filter goes in far right).

I've configured AUX RX to come from the supplied BNC connector as I don't have a KAT3 installed and I want to be able listen to separate bands. True diversity rx is a show stopper. I have an 80m doublet and a 40m quarter wave vertical antenna and was listening to someone in the EU calling for and working JAs. The JAs were masked on the doublet by EU muppets calling back, but the vertical still allowed me to hear the JAs in my right ear through all the EU QRM in my left ear!

Experience with the K3 main rx has taught me that I only need 2.7KHz tx/rx (5 pole) and 2.1KHz rx (8 pole) roofing filters to cover all modes in the sub rx. This is partly due to a design flaw in the K3 which automatically selects the narrowest roofing filter for the selected DSP bandwidth. If there was a manual option, I would buy and fit more roofing filters on the basis that 'I' could choose when to use them. i.e. The K3 selects a high loss narrow roofing filter (500/400/250/200, if installed) and then tries to amplify the output back to the original input level, just because I selected a lossless DSP filter bandwidth of anything at or under 500Hz. If you don't fit these filters it has to stop with the narrowest roofing filter fitted (2.1KHz in my case). This means less internally generated noise and no QRM difference in certain band conditions, a win-win in my book. Of course there are band conditions which suit having a tight roofing filter, but I'd like to be the judge of that!

Anyway, the usefulness of the K3 has skyrocketed with the addition of the 2nd rx and makes my MkV even more redundant than it was. I guess I'll have to think about selling it on before it dies of lack of use.

Parcel Force and rip-off Britain

My parcel was intercepted by the Glasgow depot of Parcel Force (11 miles from my home).

So in summary:

1) You pay US Postal Services for international delivery to your door.
2) When the parcel arrives in the UK, Parcel Force intercept it and won't deliver to your door.
3) Parcel Force charge £9 "handling charge" for you to come to their depot and collect the intercepted parcel. Parcel Force then collect UK tax (20%) on the item and the original postage charge.


Parcel Force - Charge US Postal Services for delivery within the UK, then don't bother?

US Postal Service - Charge you for delivery to the door, knowing full well they can't or don't have to?

UK government - Charge you VAT on a US postal service that they have a hand in making sure can never be complete.


You - US Postal charge + UK Handling charge + UK VAT on US Postal charge + Petrol + inconvienience + anger at being charged for services you never get.

Welcome to Rip-off Britain!

Wednesday, 9 September 2009

K3 FW V3.30 NR notes

Firmware version 3.25


x(selects values of Beta (gain), decay, and delay (how long the NR
algorithm waits to process a signal))

y(selects amount to processing of signal 1(Dry, unprocessed)- 4(Wet, processed))

Notes :
All selections 61 taps.

Firmware version 3.27


x(selects the length of the filter)

y(selects values of Beta (gain), decay, and delay (how long the NR
algorithm waits to process a signal))

Notes :
F1 = 121 taps, F2 = 91 taps, F3 = 61 taps, F4 = 31 taps
Noise reduction less aggressive with more taps.
The 3.27 NR F3-1 is *identical* to 3.25 NR F1-4.
The 3.27 NR F3-2 is *identical* to 3.25 NR F2-4.
The 3.27 NR F3-3 is *identical* to 3.25 NR F3-4.
The 3.27 NR F3-4 is *identical* to 3.25 NR F4-4.

The 3.27 NR F1- is "lighter" than the 3.25 NR.
The 3.27 NR F2- is a little lighter than the 3.25 NR.
The 3.27 NR F4- is "heavier" than the 3.25 NR.

Firmware version 3.30

Fx(1-4)-y(1-4) as 3.27 above

M Fx(5-8)-y(1-4) as 3.25 above

K3 mods completed

K3 Ser: 1293
Arrived: 20/7/2008

Mods carried out:

1) 10/01/09

K3 AF Mod kit, Rev B

2) 30/08/09

K3 Synthesizer ALC Modification

K3 AF Output Mod Kit, Rev C

Improving the Immunity of the Rear-Panel RS232 and Audio Connectors to RF

KPA3 12V Sense Mod, Rev B

K3 Extreme Signal RX Protection Mod

3) 02/10/09

KRX3 Installed

KRX3 Subout connector keyed

Front panel microphone circuit modification

K3 Negative ALC and Ext Band Data Pull-up Mods, Rev B: REMIOUPGD

4) 31/10/09

K3 VFO Noise Mod, Rev C

IF Output Buffer Gain Modification

K3 KRX3 (sub rx) filter choice

I wanted an 8 pole filter for 0Hz offset to allow true dual rx without the 'slow beat' audio problem.

I had the option to pay $90 extra to SWAP the stock sub rx 2.7K 5 pole for an 2.8K 8 pole and of course I'd have to spend another $125 to match it in the main rx.

In the end I paid $125 extra, kept the stock 2.7K 5 pole and bought another 2.1K 8 pole . I already have a 2.1K 8 pole in the main rx, so having one in the sub rx will allow me to lock the rxs together with a vert and a horiz antenna and listen to both at the same time without 'audio beat'. I also paid $30 extra to get the new 2.7KHz matched (-0.93KHz offset) with the existing one. So hopefully I can get the best of both worlds for not too much outlay.

I recon the 2.1KHz 8 pole roofing filter will be sufficient for SSB/DATA/CW in the sub rx. I'm sure the DSP filter width can more than handle DATA/CW inside a 2.1K roof. SSB through the 2.1KHz is fine (better if the shift is adjusted down 200Hz or so), but it excels on a busy/noisy band. Even in this configuration it should still beat most other radios out there.

Saturday, 28 February 2009

Small Wonder Labs SW40+ and embedded K1EL K-PCB (K12) keyer

Small Wonder Labs website:
and K1EL Systems
are two of my most visited websites for QRP gear and ham gadgets. In the past I bought 2 of the SW+ series QRP rigs (80 & 40m) and was and still am really pleased with their performance.

I really missed a keyer though and bought an external K12 keyer from K1EL to use with both rigs. This worked fine, but the whole point of these small rigs is their simplicity and portability. So to keep things simple, I decided to buy the same keyer chip (K12) but in K-PCB format which was small enough to mount inside the transceiver case.

The K-PCB kit takes around half an hour to build and the same again to mount inside the SW+ rig (it's so light I just used cable ties). The kit is $10 which is unbelieveable value for what you get and it fits easily inside the SW+. Unfortunately my kit was missing a 1000pF cap which I replaced from the junk box and the 2N2222 NPN transistor (used to switch gnd to the keying line of the SW+) had to be replaced.

The only slight question was how to get the sidetone into the audio chain of the rig? The K-PCB has a low level AF output for this purpose and after some experimenting I found that the best place to connect it to was the top of resistor R10 (vertically mounted) on the SW+ pcb. That done, I could hear CW commands from the keyer chip through the RX audio of the SW+.

Have a look at the above websites for details on the two kits they really are worth every penny.

Thursday, 5 February 2009

IOTA 2009. Shared serial number pool with Wintest

MM3T will be multi-op for the first time with myself and Simon M0GBK taking up the challenge for IOTA 09. We're off to the isle of Skye this time, but will still be EU-8 for the benifit of SCP files out there. We will have 2 stations operational for 24 hrs and will be operating all bands on both SSB and CW.

One station will be on mults only and the other station running for an hour, then we'll swap over. We will be using Wintest contest logging software, which can keep track of each stns contacts (RSGB requirement) and contribute both to one log (duplicated on both computers for safety). This means the stations will aquire sequential serial numbers from the same pool. The laptops will be linked via a router and if a mobile signal is possible, the cluster will be shared across the network.

The sharing of a serial number pool from Wintest presents some problems. It is possible for both stations to log the same serial number (if enter is hit on both laptops at the same time). It's also possible for the serial number to increment just before you hit enter (due to the other station finishing a contact before you). To avoid this contention for serial numbers, an operating procedure must be in place. I have found it is best to put the onus on the mult station to avoid contention as this station normally has more time to think about it:

Mult Station Operating Procedure:
Wait till the running station has just completed a contact. Dupe it while he is calling CQ, thus reserving the next serial number. This should be done quickly before the running station requires the next serial number. The cursor is then moved onto the dupe ready to edit it with the next station worked. In this way, serial numbers given out never need changed at the last minute and are guaranteed to be unique.

Tuesday, 27 January 2009

Delta 44 sound card and SoftRock K3 noise spikes

I had been plagued by some on-screen noise spikes on my K3 panadapter. One of the noise spikes was mirrored approx 48KHz apart on my 96KHz visible spectrum. My delta 44 sound card has got 4 inputs and 4 outputs on it's remote head. I had been using inputs 1&2 for my I&Q from the Softrock.

To make things easy, I had purchased an audio splitter lead from Maplin which allowed me to plug 2x 1/4" mono jack plugs into the soundcard interface and then go stereo to the softrock via a 1/4" stereo plug to 3.5mm stereo jack lead. All in all that made 3 connections per audio channel. I decided to make my own lead with the correct connectors at either end, thus missing out the centre splitter to lead connector.

The mirrored noise spike is now history! The lesson learned, is that you can't have any intermediate connectors in the lead between the soundcard and the K3 without risking on-screen noise spike "funnies".