A dish for Es’Hail-2, QO100

Last year I experimented with using a 13cm band yagi for the up-link and an LNB strapped alongside my horn on the dish I use for terrestrial work for the down-link.

I’ve now put a dish up for the Qataris’ Es’Hail-2 satellite. It is a 1.1m off-set PrimeSat dish.

Prior to putting it up,  I had bodged a bit of aluminium  box tube to take the dual-band feed. I checked the dish’s focus with a few stick-on mirrors and the sun as an light source. There did seem to be a bit of distortion in the dish, though it looked in excellent condition, with no visible damage. I may be able to squeeze out this distortion using the braces for the LNB arm.

Bearing in mind how windy it gets here I’ve used belt and braces in mounting the dish. I decided not to get the larger 1.3m dish. I felt the 1.1m dish would be easier to manoeuvre  up to the roof and also it would be less affected by wind. I’ve used two steel chimney lashings to hold two brackets. I decided the usual aluminium pole might not be up to the job, so I set a section of steel scaffold pole in the brackets. The dish’s two clamps are fixed to the bottom of the pole. In case of the dish clamps somehow working free, there is a third clamp at the bottom of the pole to stop the dish dropping off.

I’ve fitted braces to the LNB arm to hold the arm steady in the wind.

Being low down on the chimney and on the easterly side of the house, the dish is in the lee of the strong westerlies and south-westerlies.

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The 13cm patch antenna in the bigger plastic box is not really working as circularly polarised. It is more like linear, effectively from a dipole, but the return loss is quite good. The patch is fed with a shortish length of Ecoflex 10.

The LNB has a bit of “satellite” coax taking the signal back into the station. I found the connectors on my thin “WiFi” coax were very poorly fitted. I use this to carry the 27 MHz reference oscillator signal to the LNB. I soldered a proper SMA connector on the LNB end of the cable. An LNB lens takes the signal rom the dish which is then piped along a short length of copper waveguide (22mm domestic copper pipe) into the LNB. The waveguide is held by pipe clips mounted on short lengths of stainless steel studding. The LNB has a bit of a twist on it in an attempt to optimise the match to the polarisation from the satellite.

I sealed all the connections with self-amalgamating tape.

See Dual Band Feed construction.

Note: I had originally mounted the N-type socket for the patch feed with the socket mounting flange inside the plastic box, but this meant the N-plug did not mate reliably, so I re-mounted the socket on the outside of the box.

23-April-2020 opening on 3cm: Kjeld OZ1FF

I was chatting to Tony on 3cm. We were checking beacons on the continent on 3cm. He could hear DB0GHZ which I could not. I could hear beacons in the Netherlands which he could not: PI7ALK, PI7RTD and PE9GHZ. Neil G4DBN joined us.

A few of us worked Kjeld in JO45BO at 670 km. I chatted with him on SSB. He gave me 55 for my 3W to the 80cm dish.

23-Apr-20 1949 OZ1FF 57 55 JO45BO

Usually, when I can hear DB0GHZ then I can work Kjeld, but I couldn’t hear that beacon this time. I could hear no other beacons except those in the Netherlands. Tony is not that far from me, but his beacon view was completely different to mine.

28-December-2020 SHF UKAC

This was my first UKAC this year. The Microwave Modules 70cm transverter wasn’t working on PTT for some reason and was defaulting to RF Sense, so I struggled a bit on 13cm. It is nice to have 13cm going again. I need to improve the Noise Factor of the pre-amp in the box on the pole, but that will have to wait until the weather calms down.

It was all pretty local stuff on 13cm:

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It was even more local on 3cm:

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26-Nov-2019 SHF UKAC using 13cm and 3cm bands

I hopped about between both bands. On 13cm it was was nice to work Pete G4CLA again. Keith G4ODA was my best DX (longest distance) at 117 km. So my contacts were all pretty local really. I used 25W into the coax to the antenna box, so the Andew amplifier was under-driven.

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On 3cm, my initial contact was with Peter G3PHO. Our usual reflection point worked well to get round the hills. Keith G4ODA was my best DX (longest distance) on this band.

The rain was in the wrong places for rain scatter.

Denis G3UVR was much easier to hear on 3cm than on 13cm, and the dish is mounted a bit lower down than the 13cm yagi.

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22-Oct-2019 SHF UKAC 3cm and 13cm

I worked a few locals on 3cm, collecting my partner from the station in between. I could just hear David G4ASR in the noise, but not strong enough to work. I had tilted up the dish a tad in order to clear the ridge of trees. Anything south is a problem. I failed with John G4ZTR. Kjeld OZ1FF didn’t respond to my meeps on ON4KST KST chat. So about 400 points on that band maybe.

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I had taken the relay box down from the pole the previous day for 13cm. That Tue eve I finally found the fault. I had added an LED to show when the relay was on transmit. This drew just enough current to have the side effect of latching the relay to receive (energised), so no RF out on transmit! I disconnected the LED & the relay worked. So I just lashed it up on the bench. I worked Denis on about 1W at the antenna. Then I cabled in the linear with some attenuation to get 20-25W for a couple more. I tried John G3XDY near the end of the contest and logged what I heard. Then I timed out.

Denis G3UVR was easier to hear on 3cm.

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I’ll try a low-current LED. If I get a good spell of wx, I’ll put the box back on the mast & get the pre-amp nearer the antenna. I haven’t tried the relay or pre-amp before. The Narda relay is nice & chunky, but its markings suggest it is only rated up to 1 GHz.  I may have made the Noise Factor worse on receive, but I have some more dB on transmit. I’ve included a Band-Pass Filter in the box, so that worsens the NF a little more.

At least all the control circuitry seems to be working: sequencing, 12V to the pre-amp, 24V to the antenna relay etc. The 40el Wimo yagi is back up on its jockey pole so I can do terrestrial 13cm again. It has been nearly a year since I started upgrading 13cm with a pre-amp and linear.

The SG-Labs transverter is now in a box in the shack, with reverse-polarity protection, sub-band switch: 2.3 Ghz, 2.32 GHz and 2.4 GHz, power switch, ref. osc. input switch, indicator LEDs, power switch and a nice Anderson power plug. I want to add drive power switching and a monitor meter.