As busy few days radio wise!

NFD took place this weekend and I was part of the Clifton ARS entry (G3GHN/p) from near Maidstone in Kent. 

I provided a full station, IC-756Pro, PC running N1MM, Microham Microkeyer, 9.5m mast and a doublet antenna to go with the club’s auto ATU. It is the first year we have run a doublet fed with open wire, in the past the ATU was at the top of the mast at the centre of the “dipole”. This time we had 50ft of open wire feeding the 260ft long inverted-V.
This seemed to be a better antenna than previous antennas on all bands, but especially on 40 and 80m. I had a panic when AATU did not tune the antenna on the cw part of top band, but did higher up in the SSB section. We played around with the length of the antenna, to no avail. G3JKY came to the rescue and commented that the voltage at the feed point must be too high and that we either needed to dramatically change the length of the open wire (we weren’t sure by how much) or add some capacitance at the bottom of the open wire feeder when using top band. We were reluctant to cut the open wire in case it made things worse so went for the capacitance route by fitting an so-239 across the terminals of the AATU and plugging a random (50ft?) length of co-ax into it. As the co-ax was open circuit it provided enough capacitance to help the ATU do its stuff on top band. Well done Jakey! I couldn’t have come up with that. I now need to learn how to optimise the open wire length so we don’t have that performance again! Any idea, readers?

On the air things went well. HF conditions seemed poor on Saturday and I go us to 9pm with 200Qs in the log including a one hour arte of 58 around 8pm. After all the effort of getting to site and putting the station up I was pretty tired by then. JKY took control overnight with a sterling 215 Qs between 9pm and 7am – 136 on top band for a good points haul. We had an hour off for breakfast and to solve some problems with the co-sited 2m backpackers station and then I took it to the end to produce a final score of:


Band                QSOs              Pts
1.8                   135                  1020
3.5                   114                    388
7                      140                    462
14                    115                    376
21                    39                     141
28                    25                     168
Total               568                  2555


A winning total? Not even close. Better than last year by quite a long way and the conditions on 10 and 15m were better last year as well so overall I have to be pleased. Its still very tough with only two operators though!


Some more data:
QSOs

Band                 Total               G3JKY         M0BPQ        
1.8                   135                   135                        
3.5                   114                    63                    51           
7                      140                    14                  126          
14                    115                                          115          
21                      39                                            39            28                      25                                            25           
Total              568                    212                  356   


G3GHN/p Max Rates:
2008-06-07 1504Z - 2.0 per minute  (1 minute(s)), 120 per hour by M0BPQ

2008-06-07 2015Z - 1.3 per minute  (10 minute(s)), 78 per hour by M0BPQ

2008-06-07 2047Z - 1.0 per minute  (60 minute(s)), 58 per hour by M0BPQ

Over a month since my last post – if anyone is reading that is, but lots has happened on the radio front.

I now have a three element yagis for both 4m and 6m on a telescopic pole in the garden. I finished the rotator installation this morning. I only have one feedline at the moment, 35m of LDF4-50, so until I fit a relay I have to dash out, drop the mast and swap over the n-types. Not ideal, but at least I am on the air.

The miniVNA has been amazing to use during this process. 


The 6m Moonraker antenna was picked up at a rally for £25. I can tell why – it was rubbish! The miniVNA showed that it was resonant on 48.250MHz. Fine for video, hopeless as TX antenna. A quick nibble of the DE with a plumbers pipe cutter and re-adjustment of the gamma match and it is now on 50.1MHz. I have made a number of QSOs via SpE but I am not confident of the design of this antenna, so I will have to model it to see what it is like. More news later


The 70MHz yagi is a DK7ZB 28opm design that I built two years ago. Martin’s website suggests that you mount an flange co-ax socket on the balun box to attach the feed line. I was rather worried about water ingress with this system so decided to use a flying lead and a cable gland instead. This made grounding the co-ax shield a real pain as the IP66 box I had chosen was a bit too small and made the system rather mechanically weak. Upon reviving the antenna, the balun assembly had shorted and I had to cut it out of the box and build a new one. If I build another DK7ZB design I will follow the instructions more closely or use a bigger box! I see that a couple of people are producing kits of materials for these antennas which makes life much easier as we can only get imperial sized materials in the UK.

Bad news on the radio scouting front as the GB2GP shack is to be demolished this summer. This means the APRS station will be taken out of service in July. I must do something about getting a vertical up at home to provide central London coverage. Perhaps radio will get a new home in the redeveloped Gilwell LID, but I am worried that it is no loner sexy enough. We are currently working out what do with all the equipment as it will need storing. More news as I get it!

Good APRS news is that G5YC is now active during office hours from central London. The RF noise is intense in EC1, but it seems to doing some use gating RF to INET. With a better antenna I am sure I can get better coverage.

I have also built a APRS portable tracker based on an open tracker and an FT-60E. The GPS I bought to go with it doesn’t work so I will have to steal the car based version when I go to Southampton tomorrow to see if it works. 

Jobs to do this week are all centred around Region 1HF CW FD which takes place at the weekend. I am providing the full station for G3GHN/p and we will probably do the PW contest at the same time as not all the club can do CW at contest speeds.