Tag Archives: PSK31

Field Day Preps Complete!

My Field Day preps are done. Tested the EFHW and its ready to roll on 20m and 15m. There is 12Ahr of solar charged battery ready as well. I won’t be able to join the club at the NWS office as I have a commitment in the morning I have to deal with. I may start late but I am ready for operations in the backyard. Will get some water bottles and snacks for daytime ops. There is a 30% of rain tomorrow afternoon so I’ll keep an eye on that as well to see if I need to deploy the tarp tent. Rain means clouds so that may help moderate the heat. Today the NWS is advising people to stay indoors between 1pm and 5pm!

Tested the EFHW a bit and am finding Common Mode Current issues if I run higher than 90W. The SWR increases with power and foldback starts kicking in if I try and run at 100W. This should not be a problem on FD as I’ll be running at 5W where everything behaves itself. I’ll be trying computer logging this year as well. If things get real tough on Phone I plan to try PSK31 and have setup some DM78- macros for that.

Looking forward to a great Field Day in the outdoors!

Testing of the 40m Loop Continues

Here is a plot of my 24hr 1W WSPR signal using the 40m Magnetic Loop Antenna:


Next up tested PSK31 and JT65 with 20-30W of power. I made two solid contacts within 380 mi of the QTH which somewhat verifies the NVIS aspect I’d hoped for. I made some additional solid contacts on JT65 including to Guatemala and Cuba. The jury is still out on SSB though. I tried the Daytime Texas Traffic Net on 7.285 this morning and while I closed a contact with Net Control in Amarillo, Texas I was weak and I know there was some transmit problems on my side as the antenna was not tuned with precision. I’ll try again soon with the antenna tuned for 7.285 Mhz. The antenna held up well through the night and through a very windy day here at the QTH in South Texas.It swings around a bit so I may setup a “guy” wire to help position it. It has been largely oriented East-West. I should also note that it is about 2 S units quieter when compared to my main end-fed antenna.  So far so good!

UPDATE 1/11/2017: Made a 100W SSB contact to the Daytime Texas Traffic net. This time I tuned the antenna to a 1.42 SWR at the net frequency of 7.285Mhz. SWR behaved while transmitting and the net control copied my signal without issue. Net control was just east of Dallas in Kaufman, TX. 

More measurments on the Magnetic Loop Antenna

Band conditions yesterday on 20m were really quite bad. I had difficulty even maintaining PSK31 contacts due to QSB. I asked W3OQ across town to monitor my 5W transmission on 20m using the Magnetic loop. He was able to pick me up without issue. He was coming in at about a 54 with 100W from across town so this was further confirmation that the conditions were limiting performance evaluation. The good news is that the antenna did radiate!

So now on to the tuning range issues. I was expecting to be able to tune this antenna between 20m and 10m. As it stands now I can do 20m and 17m only. This implies that my capacitance at the low end is higher than expected. I have actually taken the antenna apart now to do some modifications to the mast and used the opportunity to re-measure the capacitance range. I have gotten some inconsistent results. The lowest measurements I get are 9pF to 108pF. The highest measurements I have gotten are 15pF to 155pF. Using AA5TB’s Magnetic Loop Calculation Spreadsheet I get the following table of expected values:

Frequency – MHz       Capacitance – pF
7                                  174
14                                    43
18                                    26
21                                    19
24                                    14
28                                    10

Using the Mini60 Antenna analyzer with the cap at either extreme gave me a result of 8MHz with a predicted capacitance of 133pF and on the other end 20MHz corresponding to 21pF. This indicates that the actual capacitance of the system is running a bit higher than my measurements. This sets up the following experiments next time I get the antenna reassembled:

  1. Tune antenna to each frequency and then measure the capacitance at that point to compare against predicated values
  2. Determine how much capacitance needs to be added to achieve tuning on 40m. This is fairly straight forward by placing various fixed capacitors in parallel with the existing variable cap. My thought is to add a switch to allow use on 7m

The big problem will be fixing the tuning issue on the higher bands. I am searching for another capacitor now just in case. This will pretty much all wait until I receive the 6:1 shaft gear so that I can improve the tuning sensitivity. Meanwhile I am going to work on the tripod mount and the mast to get rid of the cable ties.

UPDATE: Found the actual specs on the capacitor I am using an confirmed that the range is 20 – 120 pF. This would confirm the tuning range from about 8.4MHz to 20.7Mhz. This is a two gang Capacitor with a range of 10 to 70pF and the other with a range of 10 – 50pF. I have these wired in parallel giving me the 20-120pF range. I should be able to use just one gang and get the range back in line. Simple enough fix!

Installed a SignaLink for Digital modes

Installed a SignaLink USB for working digital modes to replace the digi-interface I had used previously.

Photo Jul 23, 6 37 56 PM

It works a little different than what I am used to in that the transmitter stays at 100% power and the power output is adjusted using the SignaLink’s TX control. I tested it out on PSK31 and made two contacts with no issues reported at 30W. The SignaLink also lets me use the Faros software for the first time. Faros monitors global beacon frequencies on HF and plots which stations are heard. The nice think about Faros is that is uses my antenna and receiver system at my QTH so the results are real-time view of current propagation conditions.

Working with HF Digital

I finally configured HRD for PSK31 and have now been making most of my contacts in this mode. Amazing how you can make DX contacts with 30W! Saw some Contestia signals on the waterfall today but didn’t try and make any contacts.