Nov 11, 2009

Upgrade current VHF station

Planned changes

There's a few reasons why I'm planning some upgrades on my current VHF station. First there's the annual wear and tear; the 17el 6.67m 144MHz Tonna yagi has a bended boom, due to a storm last spring. The coax is some 5 years old and has a few connectors too many along the path. I want to raise that antenna to the max level officially allowed, which will involve another 1mtr above street level. There's an older 4el vertical yagi for long distance 145 FM repeaters for which I have a replacement 5 el version ready. The 70cm vertical omni and yagi combo is still awaiting going into service. And them some more minor things.
Then there's plenty of equipment in the shack which needs to be sorted out, optimised for performance and operation.

Check current beacons
Just for fun let's check two popular beacons.
Now this surely is very subjective since there are so many criteria involved which change from day to day. The weather today is cold, cloudy and moist. The FM repeater at 100km distance is a few dB down and shows some more noise on its signal than what is normal.
Waiting for the right up-swing in the very slow fading (several minutes to be exactly) I copy:

DB0FAI (A1A) on 144.490 from JN58IC
This German beacon uses a 16 el yagi mounted to a cows barn and puts out 100W pointed into my direction. Distance is 545km.
You can find more info on

The displayed frequency shows the 28MHz IF ouput of the transverter plus its LO offset.
The beacon is at times pretty loud; some 34dB above the average noise level.

HB9HB (F1A) on 144.448 from JN37QF
This Swiss beacon puts out 10W into a 2el yagi also into my direction. Distance is 507km.
The location is on a mountain at 1395m ASL.
Details can be found at:
The F1A transmission effectively shows 2 signals after detection in CW mode with a 1 KHz difference. The signal on 448 sounds inverted, the one on 449 is normal. This makes finding HB9HB, which is always very weak at my place, both challenging and a good performance test for the receiving equipment.

Used equipment:

- Bended 17 el Tonna Yagi @ 12m ASL
- 25m Ecoflex 15 + 9m Ecoflex 10 coaxial cables
- Elecraft XV144 transverter (28Mhz output)
- home made 3dB splitter
- Modified Elecraft K2, optimised for 28Mhz
- Perseus SDR receiver

I'm using both the Perseus SDR as well as the Elecraft K2 for listening. The Perseus offers valuable virtual data, the K2 is the slightly better receiver. The 3dB splitter has no negative effect as there is plenty of signal from the transverter output.

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