SQ5CBA

9th Masovian Radio Picnic in Celestynów

Filip SQ5CBAwrite-up · full post →

Marian SQ4MNbench hero · investigation →

About two hundred radio amateurs in the woods of the Forest Education Centre: a campfire, barbecue, sausages, coffee and tea, talks in the shelter and a stratospheric balloon with a DVB-S2 TV transmitter. The Wanda crew — SP5MAK, SQ5PIT, SQ5DAN, SP5XVS, SP5MOR — Marian SQ4MN, souvenir badges and mushrooms from the nearby woods.

On a separate page: the programme, photos and the bench investigation — 41 seconds that changed the balance of power in the shot. Full write-up →

From Stary Mokotów to Łysa Góra

Filip SQ5CBAQSO · full post →

Icom IC-9700radio used for this QSO · up to 75 W

From my QTH in Stary Mokotów I can get into the SR7KI repeater on Łysa Góra. In a straight line it’s 149.8 km due south, and SR7KI’s antenna is 120 m above the summit, on the RTCN Święty Krzyż tower. There’s no line of sight: for 25 km the path is beyond the horizon, and the signal still gets through as it diffracts over the horizon’s edge.

On a separate page you’ll find the route map, a terrain profile with link budget, trivia about Łysa Góra (night-time Warsaw was once photographed from the boulder field) and ready-to-use SR7KI settings: 438.725 MHz, narrow FM, CTCSS 88.5 Hz, FM-LINK network. Full post →

From a field near Łęczyca to Kutno

Filip SQ5CBAQSO and photos · full post →

Icom ID-52E PLUSradio used for this QSO · 5 W

On 12 September, before sunset, in a field by Topola Szlachecka in the Łęczyca commune I made a QSO via the repeater SR7KU in Kutno using a handheld Icom ID-52E PLUS. In a straight line it’s 18.7 km to the north‑east, almost exactly the radio horizon for a handheld and a repeater antenna 12 metres above ground.

SR7KU operates FM on 70 cm: receive on 438.925 MHz, transmit on 431.325 MHz with CTCSS 82.5 Hz. On a separate page there’s a route map, a terrain cross‑section with Earth’s curvature and the Fresnel zone, repeater details and ready‑made radio settings with a CHIRP file. Full post →

An antenna you won’t find in any book

Marian SQ4MNdesign and photo · full post on a separate page →

Marian SQ4MN built an antenna for two bands at once, 2 m and 70 cm, from elements left over after building two earlier antennas. The aluminium rods, instead of waiting for “someday”, got a common boom, and between them stands a gleaming folded dipole made from copper tube. In the background, as usual with Marian, the skyscrapers of central Warsaw.

“It works superbly” — writes Marian. He won’t give any numbers though: “I don’t publish parameters, as it would be taken for cheating on my part. You won’t find it anywhere in the literature, because it was created in my head.” He considers the dipole the most interesting element: the loop made of copper tube is his own design, which he also uses in other antennas. “I don’t like open dipoles” — he adds.

Two curiosities to finish. A folded dipole has four times the impedance of a regular one (about 290 Ω instead of 73 Ω), and the parasitic elements of a Yagi bring it down to around 50–75 Ω. And 3 × 145 MHz = 435 MHz, the centre of the 70 cm band. More physics, the history of the Yagi antenna and the “classified” data sheet await on the separate page. Full post →

Wanda: 305 metres above Warsaw

The most‑used 2 m repeater in Warsaw has its own page. SR5W “Wanda” transmits on 145.750 MHz from an antenna on the top of the 300-metre Kawęczyn Heat Plant chimney, so five watts from a handheld is heard across half of Mazovia. On the page: ready‑made FM and DMR settings with a “copy” button and a CHIRP file, a radio horizon map with distances to towns, an animated diagram of how the repeater works and operating etiquette.

There’s also a history documented in public listings: Wanda appears on the PZK (the Polish Amateur Radio Union) list from 2008, in 2010 it was silent while the licence was being renewed, and from 2025 it has a new licence to 2030 and operates in mixed mode FM + DMR. Photos of the chimney come from Wikimedia Commons under free licences. Wanda’s full page →

A boom that stopped dancing in the wind

Marian SQ4MNantenna and photos · full post on a separate page →

Marian SQ4MN sent a photo of his antenna’s new incarnation on 70 cm: a long Yagi with vertical elements hangs on an upper‑floor balcony, and on the horizon you can see the high‑rises of central Warsaw. The novelty is under the boom — there’s a second, thicker tube running along there, anchored in a heavy clamp on a steel bracket and reaching all the way to the reflector. Instead of an antenna hanging on a single mast mount we now have a rigid frame with two support points.

The difference is bigger than it looks. Cantilever deflection grows with the cube of length, and wind load with the square of speed: twice the wind speed means four times the force at the boom tip. The second strut knocks the deflection down by an order of magnitude, the clamps stop taking the strain, and the cable no longer chafes on the edges.

“I haven’t noticed any deterioration in the parameters,” writes Marian. And rightly so: the tube parallel to the boom lies perpendicular to the elements, so to a vertically polarised wave it’s almost transparent — just like the boom itself. The pattern and SWR stayed where they were.

A day later there was a shot from the street. From the pavement you can see the whole scene: the Yagi projects well beyond the balcony line and sits next to two satellite dishes, and one storey up a white‑and‑red flag flutters — as if someone were already testing a wind indicator. Good news for the contest: the ribbon will be visible from street level.

Three callsigns, one bridge

We three met on the Świętokrzyski Bridge — a classic eyeball QSO, that is, a face‑to‑face contact. The reason for the crowd around us: a partial solar eclipse, which in Poland happened exactly at sunset — the disc slipped below the horizon with a clearly ‘bitten’ edge. The path of totality ran that day over Greenland, Iceland and northern Spain.

The bridge also turned out to be a decent QTH: a dozen or so metres above the water and an open horizon both ways along the river — on 2 m and 70 cm that kind of ‘free height’ does more than the best preamplifier.