Had a quick chat with a local ham (Elvin BBA) on 144MHz using the transverter yesterday and all is well apart from being 2.8KHz low on the frequency display on the K3. Actually there is a menu in the K3 to adjust offset in the firmware, but I'm already fully utilising +9.9KHz offset (max) so I'm actually 12.7KHz off. I thought it was something I had done, but apparently Elecraft's supplied crystal part has questionable accuracy. I got an e-mail from another XV144 user saying he had exactly the same problem until he replaced the Elecraft crystal with one from a local supplier and it came up bang on frequency.
So far the XV144 seems to have a very lively RX. Using my 5 ele yagi in the loft (K3 on SSB, 2.7KHz width) I get a constant S6 of noise on the K3 with no pre-amp. In comparison the IC-275E shows S0 on the same antenna. Switching in the dummy load brings this down to S3 on the K3. I used the Elecraft XG-2 mini module to calibrate the K3 S meter on 10m so the discrepancy must be the with the IF input. Listening to GB3ANG beacon it seems louder on the K3 than the IC275E. On both radios I'm getting QRM that sounds like frying bacon (blooming Christmas lights and toy chargers!) so I would expect some signal strength to be registering. I'll need to take the K3/XV144 somewhere quiet and see what it's like, I might even be able to dispense my ext pre-amp.
I have the crystal oven option and on initial switch on from cold the RX drifts about 1.5KHz in under 10 secs then stabilises. I left the radio sitting listening to GB3ANG for about an hour after initial switch on and when I came back in it was still bang on, so pretty happy with regards stability.
The TX side is typical Elecraft. On first tx after power on or band change it takes 5 secs worth of tx audio before the output power starts ramping up to the set level, 3 secs more tx after that it achieves the set output power level and stays stable.
The manual wants the output set up to be max 20W CW key down into a dummy load (even although the front meter goes up to 30W). When set up like this, on SSB the front meter on the XV144 just peaks to 15W (up to 10W LED on solid, 15W LED flickering) on tx audio. This all seems pretty normal when considering PEP to average power readings. Once calibrated using my external watt meter, the output power LEDs on the XV144 accurately track my average power reading. TX audio is reported as a good representation of my real voice.
We'll have to wait to see what Elecraft can do with the offset problem.
Sunday, 26 December 2010
Progress continues on the XV144. Now through the boring mass resistor/capacitor fitting and on to the bigger parts. Board is now looking a lot busier. The low quality plastic trimmer supplied with the kit has no possible chance of fitting the hexagonal inductor trimmer pot. I had to 'sharpen' mine to allow an easy fit. I'm taking my time, doing things right and so far haven't made any mistakes. Christmas has been and gone now (thank goodness) so now only have a birthday, a curling match, a new year party and visiting relatives to slow progress :-).
Friday, 24 December 2010
Merry Christmas All,
Working on my XV144 right now. No surface mount stuff to fit, so all similar to any other kit.
Some things to note:
1) Some of the component pads are smaller than normal, so a really fine tip solder iron tip is necessary (0.3MM or smaller), also really fine solder 60/40 0.5mm is a must to avoid shorts/splashes.
2) There are large copper fill areas on the PCB which act like a heat sink which wicks the heat away from the pads. This means solder tends to prefer to stick to the tip of the iron rather than to the pad. The fine iron tip exacerbates this situation. The solution is a proper variable temperature solder station and maybe a fine iron tip (chisel profile?).
3) Not all component leads when bent close to the component body will fit the PCB. The component has to be offered up and leads bent to fit PCB. Takes a bit longer, not as good/easy as the K2.
4) Some of the larger wattage resistors have to be mounted above the PCB to allow air flow all round the component.
5) Elecraft manual is brilliant as usual
Progress so far-