G4NRT It is not absolutely necessary to chop the horn off. You can also drill a 22mm hole into the plastic cap and slide it over the tube until it makes contact with the inner parts of the horn/waveguide. Some (acid free!) silicone to make it weather proof, et voila : -)
Posts by PA3FYM
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No, that is a POTY in one dish ; -)
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I drew a circuit diagram at our radioclub (where we have pencils and no sharpeners ; -) when somebody asked me how I do it. See picture below.
Use Thomson's formula for f = 25 MHz and fit the components to what you have in the junkbox. -
Like G0MJW said and having built 23 pieces myself: The plot looks good.
The sharp dip at 1880 MHz is due to the resonance of the reflector.
Perhaps you may tweak a little to have both 2.4 GHz dips such that 2400 MHz is centered (and thus not having the least RL) for truely circular polarization.
16 - 20 dB RL is good enough.
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Actually I miss the lovely CW signal if it's not there.. it's a good reference to see that everything is normal
Same here, although I don't have enough patience anymore to decode the messages ; -)
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DB2OS I look towards these signals from a different perspective. At least these people are able to produce a (weak) signal over the transponder. Something a lot of licensed forum members here seem incapable of.
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Yep, unfortunately it's true. I couldn't believe my ears when somebody told me.
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Just try to squeeze it in as far as possible. Be sure that you're able to turn it.. so tweak/file a little until there is neat fit.
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I have no insight information, so the following is an (educated?) guess: Looking e.g. at BADR4's Ku-band footprint (which is not a global beam!) you see that in the centre it's 50 - 51 dBw and at the edges 6 dB (or more) less, which translates to dish sizes in order to receive the TV programs.
The transmit Esh2 Ku EC-horn has 17 dBi (see specifications), so this translates to a certain -x dB (x being the design specifications) beam width from which the relative loss / output power can be derived. Because the beam is global I think around 6 dB may be added .. which translates to half dish size.
Cf the sheet: 89cm dish at EOC vs 50 cm dish in Coverage peak = 'around' 6 dB (5 dB to be precise).
Of course the values in the sheet are the design goals, so I am not aware which values are realised ... I did not sign any NDA concerning Es'hail-2 ; -) -
How I read that sheet: these are worst case numbers (second bullit).
In the sheet the word 'Europe' is not mentioned, at least I do not see it.
'Coverage peak' <-- say cantral part of the footprint
'EOC' <-- end of coverage (say 5 - 10 degrees elevation)
'Elsewhere' <-- well ... elsewhere ; -) -
G4NRT Don't worry, we'll spoon feed you accordingly ; -)
Yes, that is the place ... you'll notice that the outer diameter of the 'flesh' is almost20mm (somewhat more) , so with a file and some sand paper the diameter can be reduced so that it fits neatly in the copper pipe. (Beware that the file dust stays out of the LNB-waveguide)
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HB9RYZ I don't have a Bodnar GPSDO so I can't help you directly with settings, the only advise I can give: "Try it" and see/hear you've the beacon at (14x).550 ( x = 4 - 7) *
* Looking at your pictures it seems that you are indeed the one with the (special) 2m option and it seems that the (seperate) converter is inside the waterproof box?
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HB9RYZ In my prototype of the transverter I use a BG7TBL 10 MHz reference where the end is terminated with a load (like in the old 'coax' Ethernet days).
The PLL IC's have sensitive REF inputs, so I should try it at the lowest drive level (8 mA) first if I owned a Bodnar GPS.
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See below the sheet I referred to (sensitivity (SFD) of the tpx is given) and also read this document
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You can calculate/estimate the 'receiving gain' of the QO-100 antenna assuming that the satellite is on 38500 km above the Earth and needs to illuminate the whole Earth with minimal 'spill over'. Assume (I don't know exactly) that you've -3 dB points at the edges of the Earth, then you can calculate the (-3 dB) opening angle and from that you can calculate the 'gain'.
But there is a calculation concerning the uplink budget in the formal/original Es'hailSat presentation for the ITU (some years ago). -
G4NRT David, I think the LNB is already modified to work with the 25 MHz reference (which is in the transverter). Note: his modified LNB's work with 5V, so do not try to connect this to a regular satellite transceiver! The reason behind the 5V power supply is that a very denoised power supply is offered to minimise phase noise of the LNB-LO.
I don't know how Rene ships the LNB, but when it has a horn on it, the horn has to be cut off (with a hack saw) in such a way that you've maximal amount of 'flesh' for the LNB-waveguide. The outer diameter of the LNB-waveguide is ca. 20mm and with some sandpaper it fits inside the dualband feed waveguide. Concerning the boxes, here is a pictrue how Rene did it himself. -
G4NRT At least the feed did shine and had a good RL when I measured it, but I don't know you got it in a (weatherproof) box/casing. Hand made for you (with love ;- ) !
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G4NRT I don't know if you ordered the 'full Monty' , i.e. the transverter built in a waterproof box etc. I am not fully aware of Rene's options, but I know he made a separate 739.5 --> 144 MHz converter on specific request for somebody. (I know because I had to write the software ; -)
Concerning the cables. Rule of thumb on microwaves is that one should keep the cables as short as (practically) possible. Depending on the size of the dish you have some power reserve. E.g. if you use a 90cm (wide) offset dish, 5W at the feed is more than sufficient, meaning you may loose 15W in the feed cable provided the end stage delivers 20W.
In the Ecoflex 15+ datasheet I read that the attenuation is 14.9 (say 15) dB @2400 MHz, so -6 dB requires 40m of this cable. In other words, 5 - 6m of cable from the TX-connector to the dish will not be a problem (and requires you need to back off your power, depending on the dish size of course).
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do1ctl Ah yes, that is of course also a possibility : -)