NAC, Tuesday 17th June.

 After last month's adventure I made the trip to the local hill to do some more 1296MHz activity.

The hill is 80m (250ft)high and has an unobstructed view for a few 10s of km.

As before, I was running 10W SSB/FM/CW and a 12 element Yagi antenna. Not a big setup, 

Everything was transported from the parking place to the top, distance to walk, about 400-500m, and steep uphill, bit I can do it alone if necessary.

If the weather behaves well, I might also go up there on a Friday evening where we have a weekly FM-simplex net on 433, 50, 70, 145MHz and 1296MHz was recently added. 10W with a good view should be quite good, especially on 1296. 

I was a bit late in getting ready, so I arrived and was ready to operate about 20 minutes after the test started, and immediately there was a QSO with extremely strong signals from another hill about 25km away. Both hills about 8m ASL, so line-of sight.

I worked the highest number of stations in this test, that I have ever done on 23cm. 

The best distance was SM6UTZ at 307km distance, and a few others were above 100km, so I have no complaints.

My antenna was, as usual, mounted horizontally, and I also worked a Copenhagen station OZ13JK, working with a 3-band vertical, I think about 2-3m above ground. That was an improvement over the test last year, when he was trying, and just making a QSO with a handheld 23cm radio and a small handheld yagi antenna.

I tested the sewtup, listening to beacons, 2 of the LA beacons were heard at about 400km, two Swedish beacons not far from Gothenburg, and the Polish SR1KOL at 370km was heard all evening.

I think there was a bit of a tropo lift, as some signals got stronger later in the evening.This was a good outing, and I expect to try it again when the weather allows.

Some Tropo on 1296MHz.

This is interesting.

The last few days we have had some good tropo over the Baltic.

Yesterday the SR1KOL in JO74TE came through a good deal of the afternoon and evening. It did fade in the late evening, and it may have been there through the night.

Distance from JO65CP is close to 270km. Given that I am using a vertical omnidirectional antenna, I am impressed of the signal coming through.

Today, I started listening in the early afternoon, and it was already there. Through the whole afternoon until writing this about 2230 (2030UTC), the signal has been there consistently. Many times with S5.

I am still impressed. Others around me with horizontal antennas hear it S9 a lot of the time, not surprising.

I checked on the map. It turns out that I have an excellent path from my antenna, sloping down to Koege Bugt, then more than 250km across the Baltic Sea. It may not be so surprising that I have heard this beacon quite often. Only a tiny low lying piece of Sweden (Falsterbo) is "in the way. When I get a horizontal antenna up again, I will monitor this path on a more regular basis.

In another direction I have the DB0VC beacon in JO54IF, I have heard it once or twice with the vertical with a more obstructed path. When I had a small horizontal yagi up about 7m, I heard it regularly at just over 180km.

Portable Work on 1296MHz, Tuesday NAC.

 With a bit of preparation, we went to JO65FH on the Peninsula of Stevns to operate a bit in the 1296MHz Nordic Activity Contest.(NAC).

I had arranged with Jorgen, OZ7TA to go there with our equipment and test out the suitability of the site.

This is the site for an old cold war radar station with a magnificent view over parts of the Baltic, so we had antennas about 42-45m above sea level with good flat land for over distances up to 20km.

I had brought my IC-905 and Jorgen his Langstone project transceiver with a 1296MHz "front end" , i.e. TX power amplifier, RX preamplifier and filter. The Langstone is based on a Pluto SDR and Raspbeery Pi 4 with the appropriate software, and will work from 70MHz to 6GHz - with different "front ends"

I brought the 10GHz transverter for the '905 and a 22dBi horn antenna to make a test of the system. unfortunately the SMA connector broke after setting up the system, so the 10GHz testing was cancelled.

On 23cm we both had extremely strong radar signals. So strong that we suspected breakthrough from a nearby radar. Later we found that many other stations had the same problem, so this was very strong propagation.

We made a few contacts, mostly with very strong stations, the weaker signals were drowning in the radar signals.

One drawback that I had not expected was the connection with the ON4KST chat. Because we had a view over the water to Sweden, the 5G connection switched between OZ and SM, so the connection was broken, almost every time I checked it.

That is how it goes. Every time we go out in the field, there is something new to learn, so let's see if we can do better next time.

Local FM "Net" on 1297.5MHz.

 A while ago a group of local hams near Copenhagen initiated the FM.Simplex Ring. in order to create some activity outside repeater traffic only.

Excellemt initiative!.

We met every Friday evening at 1900 local time.

Starting (at the moment on 433.225 (this may change because of interference from ISM devices) for 20 minutes.

Then 1920 on 51.510

1940 on 70.425

Finally ( until yesterday) 145.225 from 2000 onwards.

For a while there has been sporadic activity at 2100 on 1297.500

From now on it's an "official" part of the "ring" to operate at 2100 on 1297.500. At the first official one on this frequency we were 10 atations participating.

I could hear 9 of them and make 2-way with 8 of them. That is an excellent start.

Most of the day when I am at home, I have a radio receiving on 1297.5, so if you are less than a few hundred km from Copenhagen, and detect enhanced propagation, try a call. Someone in he area might hear you and respond.

Signs of a Local 1296MHz Repeater.

Some time ago I noticed a signal appearing on 1297.000MHz, coming and going.

When I caught it, it had an ID, like a repeater, coming up now and then.

A few of the local amateurs looked into it, and it turns out to be an experimental repeater, but not yet operational.

A few days ago it turned out to have an input at 28MHz spacing, with a CTCSS tone activation. A short transmission activated the ID, but there is no voice feed through (yet?)

I tested it myself and it opened nicely with my 10W output. Tested to see how low I could go. 5W, 2.5W, 1W, 0.5W ... still activating. Now try to go to the lowest setting of the 9700. 100mW? Still activating the ID. The receiver appears very sernsitive. Another local ham (much closer to the repeater site), could activate it with 25uW (yes microWatts).

This could become a very nice addition and create some local (or maybe not so local) activity on 23cm FM.

I may set up a low power transceiver with a small antenna, if (when) this repeater becomes active with voice.

Improvement of the QO-100 Uplink.

 Today I received a new helical feed antenna for my QO-100 uplink system, and tested it with the power amplifier I made an initial test with in the previous entry.

The amplifier mounted indoors, and with the previous unaligned feed arrangement did give a readable downlink SSB signal for people with a well optimized RX system, and I made QSOs with it.

As I am not very good at mechanical work, I used a DX-Patrol helical feed with a hole and mounting option for some LNBs. I did mount one LNB, with a TCXO, and modified for down conversion to 432MHz. I will use that for monitoring my uplink signal to the satellite.

Right now I am using my IC-905, driving the SG-Lab Power amplifier directly on 2400MHz, and a GPS stabilized LNB, mounted in a 60cm dish. This has quite good performance, although I want to try it with a larger dish. I have some lying around, so it's a matter of finding time and energy to do it.

Now, the test with the new feed gives about 15dB S/N via the satellite, and I can easily read my own signal. With the previous feed I could read my own signal with a little difficulty.

I can still improve the uplink signal, mounting the PA near the antenna, but it is quite nice to have it inside, so no weather proofing is necessary.

This is the test setup (with the LNB not connected).

2400MHz Amplifier Test.

Finally, after the winter solstice, I had a bit more energy.

I purchased the 2400MHz amplifier from SG Lab in Bulgaria. This has a good reputation for reliability, and I wanted a bit more output than the 2.5W I already had.

This is the v3, needing less than 40mW to deliver a typical output of 20W @28V power supply and 17W @24V.

I did have a signal generator using a computer control Windows program, but no usable Windows machine with a CD-ROM drive. Oops! What do we do now?

Well, well. I do have my IC-905 with variable power output up to 2W nominal.

The RF unit is in my "shack" on the ground floor, and the lab with all my test equipment is in the attic, so I picked up the controller unit and a piece of cat8 network cable, so I could control the thing from the upstairs lab. Now to get the RF power upstairs. As I only needed maximum 40mW, I could use some cheap SMA cables, RG174, two lengths of about 5m. 

This makes for a neat cheap attenuator. With the 2W output from the TRX I could measure about 30mW, using the peak indicator of the spectrum analyzer. That is good, as I can't overload the amplifier.

Because the output of the PA is 10-20W max, I needed to bring that down the level. I used a directional coupler (800-2500MHz), with 40 dB coupling. Bingo! 10W becomes 1mW. Of course a dummy load capable of dissipating the output power was connected to the "through" output.

Connecting the system I could measure about 10W out with a drive from the TRX of about 33% (650mW minus the cable attenuation) Result: 0dBm out of the directional coupler 10W from the amplifier.

Increasing the drive gave about one more dB.

This looks like to low output, but I would consider it within the tolerances of the test equipment. There is some extra loss in the connectors, adapters and cables after the output of the amplifier, and the spectrum analyzer, as well as tolerance of the input power measurement of the spectrum analyzer. so measuring 12W maximum output is within the tolerances of the minimum 15W specified from the amplifier, by about 1.5dB. That is good enough for me.

The amplifier test setup was the module attached to a cooling fin, with Kapton tape, and using some good thermal compound. 

It did not get hot to the touch by normal operation, even using full carrier FM.

I intend to use it for a while indoors, and if it looks stable, I will likely mount it outdoors. this will require a better mechanical construction, but also provide more power available to the antenna.

This setup is intended for QO-100 uplink use.

If this works well, the next step is some more power for 1297MHz FM.

1296MHz Tropo.

The past week end made for some surprising propagation on VHF/UHF into my area (Greater Copenhagen)

I did not work much o 144MHz, apart from what I call "local tropo) propagation. That is distances up to about 300km (200mi). We had some good contacts within that distance, running FM with a vertical.

The more interesting band for me this time was 1296MHz.

Both Saturday and Sunday provided beacon reception (by ear), from several countries.

Of course, the local OZ7IGY is always audible here., then 2 other OZ beacons, further away.

3 German beacons were there.

The Swedish SK1UHF, on the island of Gotland at quite a distance.

The Norwegian LA3SHF at 370km (230mi)

The Polish SR1KOL at 270km (170mi)

Finally, the Czech beacon OK0EKL at 580km (360mi)

The only antenna available at this moment is a monoband 23cm vertical with over 10dB gain. All beacons transmit with horizontal polarization, so the attenuation is considerable. With a good horizontal antenna (yagi etc) I estimate the signals would have been 10-15dB stronger, and I would likely have heard several more beacons.

Best 2-way DX was DC7QH in Berlin at 345km (216mi). This was unusual. I heard him call CQ in FM and called. When he heard "OZ" he pointed the antenna in my direction, and the signals disappeared.

Then, when he pionted the antenna about 180 deg. away from me, the signal went to S9+. Probably a reflection. He was working with 200W into a 1.5m (5') dish with horizontal polarisation. ( am running only 10W, at the antenna about 4W.

During all this there was a lot of noise from radars (at least 3 different ones), sometimes wiping out most signals. I had good use of the narrow CW filter (250Hz) when listening to the beacons. The radar peaked far above S9.

On Sunday afternoon I decided to get my radio running with WSJT-X, so I can run some DX tests. That took a few hours, but it finally worked.

Best distance "heard" with FT8 was UR5WCE at 1029km (about 600mi).

Come spring, I need to mount a (small) yagi on a tiny rotator I have available. It will be very interesting to see the improvements, including raising power to about 40W at the radio. Perhaps later a PA/preamp near the antenna, raising the power at the antenna to about 100W, also running digital modes like FT8.

This was a spectacular week end on 1296MHz, let's see what's in my future.

Nice Bargain at VHF Day.

 Yesterday, 11th January I went to the Winter VHF Day in the town of Ringsted.

As always great to meet other VHF-up people and exchange tall tales.

There is also a small flea matket, and I got two things home.

A programmable attenuator 0 - 120dB in 10 dB steps. specified up to 2 GHz. Another addition to the test equipment for the higher frequencies.

The second thing was a bit of a surprise. Someone had a Uniden scanner, the 3300 on the table, and when I asked the price he said DKK 20.- (about $3) so I took it home, thinking that if it's a brick, it doesn't matter.

I tried to switch on with the battery - of course it was dead. I found a suitable DC connector and connected 12V. Switch on, and the4 display showed something that looked like a functioning radio. Neat.

Now to find out how to program frequencies, so we can see if it really worked. Downloaded the manual and spent some time to get the right menu going. Finally I could enter a frequency. 

When I looked up the spec, the scanner should be able to run from 1240-1300MHz, so I entered 1297.500MHz, and restarted the radio, transmitting on that frequency. 

Bingo! Signal received. (Hearing audio feedback) The receiver works. 

I have not yet tested sensitivity, but even if it has poor sensitivity, I can use a preamp, and possibly a filter.

Now, a $3 radio that works on 1300MHz, that is what I call a bargain.