Last January the QSO BANAT Association added a 23 cm section to their VHF-UHF FT8 Activity contest, open to all digital modes. Tonight it was the 3rd round in this year and my second time in participating. In February I struggled with FT8 and some QSOs could have been much faster completed by using CW, as the one with Roberto, IK2OFO, whom I worked many times before in CW on 23 and 13 cm.
This time I tried FT4 in some skeds and was surprised by the excellent performance of this mode. Of cource I tried with Roberto and it was as fast as in CW. Later at the end of the contest I had QSOs with Andre, DL6AST, in FT4 on 23 cm and on 13 cm as well. After that we tried MSK144 and JT9f (my favourite so far) on the higher band, but without success so far.
It seems FT4 is more robust in handling the varying doppler shift and multipath propagation caused by airplane reflections compared to FT8.
Many thanks to the friends of the QSO BANAT Association for organizing this activity on 23 cm and not dedicating it to FT8 only. This opens space for experimentation, the heart of amateur radio!
Complainment about the need of having an elevated location and large antennas to become QRV on 23 cm with an IC-9700 inspired me to compare my regular equipment of:
TV 144 MHz
TV 1296 MHz
LNA 0.35 dB NF
3 m EcoFlex 15
3 m dish on top of the mast
with my IC-9700, usually in use for 2 m and 70 cm and a minimalistic antenna:
5 m RG213
Ringfeed for 1296 MHz, just on a metal step on the roof
The dish in the upper right and the ringfeed to be seen in the lower left on the metal step, both beaming south. As signal source the beacon HB9BBD/B on 1296.050 MHz has been chosen, 323 km away, on the Rigi Scheidegg in Switzerland, 1670 m above sea level. It is transmitting 10 w into an array of 3 dipoles beaming north.
As the whole air space between Mainz, JN49CV, and Rigi Scheidegg, JN47GA26, is visible, a lot of reflections on airplanes can be expected.
The signal of HB9BBD/B is very strong in Mainz, 40 dB over the noise usually. The gain of the dish is estimated to 28 dBD. The gain of a ringfeed may be 2 dBD and as it has just been layed down on a metal step on my roof, I assume the difference to be more than 30 db.
As expected, the signal could be received with the IC-9700 as well. It is deep in the noise, but increasing, when airplanes cross the path, audible most of the time.
Wide Graph of WSJT-X is a nice tool to display weakest signals and I very often use it to monitor distant beacons. I recommend it to anyone, who want to start beacon monitoring.
Deep in the noise is the signal at the ringfeed and the IC-9700 at about the same time as on the screenshot before. But it is always there and many reflections can be seen, increasing the signal level. Interesting is that different reflections dominate in the two screenshots. That is caused by the different beam widths of the antennas.
The conclusion is, that there is no point of not to try on 23 cm with an IC-9700 and a small antenna. In this example the difference of the receiving systems is assumed to be more than 30 dB. When using a low loss cable, a LNA and a 3 m yagi along with the IC-9700 the difference will be not more than 10 dB, resulting in 20 dB stronger signals.
Aircraft scatter relativizes the disadvantages of locations in valleys and urban areas.
A question in a Facebook group about a GPDSO for an IC-9700 to be used on 23 cm for FT8 inspired me for a quick test. As I use my IC-9700 for 2 m and 70 cm only from home, I connected a dummy load to the 23 cm antenna socket. Next was to tune it to 1,296.174 MHz (of course) and to call in FT8.
The result in brief: No problem to decode with my regular 23 cm rig (OCXO controlled). Just a moderate drift and the signal appeared about 100 Hz too low. Nothing to worry about.
But never the less, I prefer JT9f on 23 cm, as FT8 is useless on aircraft scatter.
It was nice to paricipate in the recent Microwave Contest on first weekend in June. There was a lot of activity despite the fact, no multi operator stations have been there as big guns. Meanwhile the claimed scores for DL are available and I was surprised by looking at the number of german participants on the 23 cm band. 174 stations sent their logs, which is much more than the total numbers of single and multi operator stations in the past years.
So I guess, it may be caused by the popularity of the new ICOM IC-9700 SDR transceiver, covering the 23 cm band.
Addendum June 17th, 2020: Pit, DK3WE, the contest manager, had a look for me at the .EDI files and found among those, who entered the equipment, 40 entries of IC-9700.
When looking for EA2TZ/B during a beacon check a couple of days ago, I mentioned a signal with strong doppler shift about a khz below. As I like the challenge to identify new beacons, I started monitoring it. It became a kind of a nightmare, trying to to catch the beacons callsign. It seems to be very chatty, transmitting a whole bunch of unuseful text. despite the fact I got a lot of good quality fragments via aircraft scatter, it took me hours to identify it as F1ZBK. At least I am pretty sure it is, as there is a second callsign in the end of the text: F1DND, maybe it´s the keepers call.
The text decoded so far is: —— beacon f1zbk jn38bp nancy … 854 khz … 5 watt … f1dnd … orange KA … ——- Where the “…” represent gaps and KA is the prosign for “Attention” or “New Message” (not to be used at the end of a message, like AR).
There are many beacons running in bad modes like reversed F2A or keying the subcarrier of F2A, but transmitting such a lot of stuff is worse.
After I noticed some spots for SR1KOL in JO74SE on 1296.960 MHz, I monitored the frequency using WSJT-X Wide Graph. About 400 Hz below the nominal frequency traces of a F1 signal can be seen, when airplanes cross the path to the beacon. The signal is not audible, but I am pretty sure, it is SR1KOL.
Traces of SR1KOL in JO74SE, “1000” = 1296.960 MHz. The strong signal at the very left is a birdie.
Some information can be found on the website of Polski Klub UKF: It is located on a high rise building in Kołobrzeg, 40 m above ground. The power is 3 W into a slot antenna. Beacon keeper is Andrzej, SQ1GU.
The video shows an A380 crossing the path between DJ5AR and SR1KOL. At minute 2:00 the plane crosses the first time and at minute 4:00 after a turn it crosses a second time. Mind the traces at 580 Hz in the waterfall diagram. The 1000 Hz mark corresponds to 1296.960 MHz.
Irek, SP5MX, who was involved in building the beacon and who repaired it recently, told me, the beacons reference is an OCXO withtout any GPS-lock. So possibly the beacon may transmit 400 Hz lower than defined.
At least in the morning of July 31st audible reflections could be heard via an Airbus A330. This time the 1000 Hz mark correspondents to 1296.9596 MHz.
After 10 seconds the noise becomes a kind of ‘musical’. Another 10 seconds later experienced ears can hear the tone.
As can be noticed now, the fears, many Microwavers would prefer to go to the HAM RADIO fair in Friedrichshafen, were overdone. It was a nice contest and in the 23 and 13 cm sections I worked more stations than in the last contests in May and March, as well as in all previous microwave contests I participated in June before. As can be seen in the maps, my honey pot is the east.
QSOs on 23 cm in Microwave Contest June 2018
The signal levels were very strong and I managed to work HA5KDQ on 23 cm in SSB over a distance of 830 km via Aircraft Scatter (ODX). To be honest: I am sure, we would have been faster in using CW 😉
QSOs on 13 cm in Microwave Contest June 2018
Working on 13 cm was big fun and ODX was HG7F over 817 km in a quick QSO in CW (as usual). When I went to bed at night, I already had 22 QSOs on this band with an average of 457 km per QSO.
Hannes, OE3JPC, was so kind, to send an audio record of my signal on 13 cm.
First steps have been done on 3 cm. But there is a lot of potential for improvements.
So it was not really a problem to quit two hours earlier to attend a barbecue with the family.
Recently, when getting the WAC Award for 23 cm, I outed myself, not really being an awards collector. The other day some HAMs proudly presented the first WAE awards for FT8 only contacts on Facebook. So the question was, how far would I come with VHF and up. Surprisingly I found QSLs for 42 WAE countries and 100 band points, when checking my shoe boxes and the QSL systems in the Internet.
2018: WAE III, 100 of the 106 Band Points on 144 MHz to 2320 MHz
As electronic QSLs were involved, these had at least to be imported to the German “DARC Community Logbook”, short DCL, for the award application. It´s not my favourite, because there are problems to enter and store QSOs on the GHz bands. I asked the developer about and he mentioned, that it isn´t intended for. So I decided to interpret DCL as “Direct Current Log”. No wonder, there also was no way to delete the six embarassing shortwave QSLs, it had imported automatically.