pe1chl: writing right now a second thread.. I have something 
Posts by DH2VA
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This module is mainly targeted for DATV use, as you need some serious derating to get it linear enough, probably -6dB or even more. Which results in 50-60W out for DATV. So perfectly legal.
In any case: YOU are reponsible for your transmissions. Not me or Ampleon.
Reminder: DL limit is 75W, HB9 limit is 100W (no idea why) but needs special permit.
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For those who can use a soldering iron:
Ampleon's Compact 250 W Dual-Stage 2.4 GHz Module Eases Integration Complexity
running it at the legal limit will give excellent linearity.. for DATV for example.. just look at the size: 72 mm x 34 mm. About the size of a LimeSDR mini.
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I always wondered about the limited bandwidth of the NB transponder. The designers have something in their minds that I don’t.
Excellent question but rather simple answer: Power. If you do the whole math (which is easy.. antenna gains, path loss and so on) and add some secret sauce (aka values under NDA we cannot share) the completed dinner dish will be something like 250 kHz BW for the NB transponder if you ask for reasonable SSB capability with small size antennas. You only have so much power from the satellite transmitter. Bigger transponder BW = more QSOs = less power per QSO = less signal per QSO.
On the other hand, I would be thrilled to see the transponder filling up.. which means microwave activity and the ultimate proof that microwaves are easy. Something James Miller G3RUH postulated long ago..
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Please be reminded that regardless of the actual passband, transponder traffic should stay between the two AMSAT beacons which will be present as soon as the transponder is opened for the public.
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I have significant reduced carriers on both 10706 and 11205 and no sidebands anymore. Maybe 20 dB-ish over noise.
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thanks Charlie for the clarification!
Just seeing this: under your Avatar in this forum, it says 'Beginner'. I don't think so, hi!
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The amateur transponder operates on non-overlapping frequencies for H and V, so this will not be very important.
We would still recommend users to use a proper skew setup to avoid wideband noise from the WB transponder. If the WB transponder is driven hard (which we do not suggest and do not hope!), the IM3 products may end up in the NB downlink range. That is why we designed the two transponders to have separate polarisation planes.
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Here's a photo of the PA.
Yes, it is always best to apply gate voltage before drain on any GaAs FET PA. Procedure is to start with about -5V on the gate before applying drain voltage, then carefully take the gate less negative until the correct value of quiescent drain current is applied. This only has to be done once when setting up. Normal operation would have that gate voltage present all the time (ie on receive as well as transmit) and then just switch the drain voltage on for TX. Good designs of power supplies include an interlock so that should gate voltage fail drain voltage cannot be applied.
73
Charlie
Hi Charlie,
can you elaborate on this a bit more? I believe your procedure is correct for GaAs Fet PAs but we have nowadays sometimes MOSFET or LDMOS and here the gate bias is switched while the drain stays alive as the source-drain channel is non conductive at zero gate bias.
73s Achim DH2VA
PS: great to have your expertise in this forum!
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Beacons 10706 H and 11205 V.
Dear OM, very nice signal! How big is your antenna?
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Hi Rolf and all,
just as a reminder, most position reports are results of tracking software extrapolating the latest kepler elements. The current TLE for Es'hail-2 are 2 days old and probably not relevant anymore as the control center will have stopped the drift by now with thrusters. Actually doppler measurements by EA4GPZ point to a possible maneuver a few hours into the year 2019 (UTC).
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I have my SDR stuff connected to a Raspberry Pi 3 and connect to via TCP stream from a Windows 10 desktop running GQRX and other thingies. Works via SoapySDR like clockwork.
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Hi Raf!
for now, this is the only thing to receive from Es'hail-2: the beacons on 10706 MHz and 11205 MHz. Judging from your screenshot, you are in the right ballpark concerning signal levels. Be reminded, that the satellite will eventually move to 26E after completion on the in orbit testing and AMSAT-DL will still need to do some work on the hamradio part.. thank you all for your patience!
73s Achim
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Obviously they are putting the AGC through its paces.. more input makes the transponder noise go down. So far so good!
Scary large signals though on my 90cm dish
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Found the problem. My SDR Stick is based on an R820T and this seems to have no RX at the 11205 IF (which is 1455 MHz), some sources claim the coverage ends at 1300 MHz. Connected an Airspy and all is fine.
For sanity, checked the ASTRA 3B at 11446.75 H. Huge beacon..
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Tried to switch my pol to vertical (mechanically .. ) still nothing at 11205 MHz. Questioning my antenna alignment now.. but 10706 is strong with all sidebands. Hmm.
What are you people with the 11205 signal using as hardware? I have an unmodified PLL LNB with RTLSDR behind and power injection.
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10951.5 is ASTRA 2C according to Altervista Beacon List. At 23.7E, this is well within our receive beams.
Can anybody confirm 11205 right now (2050UTC)? Don't see it at H pol.
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Hmm.. cannot see anything at 11205 MHz, but I am currently at horizontal polarisation. Do do however see something coming from the sky at 10951.5 MHz:
Anybody can confirm this? I do see the 10706 signal with its sidebands and the stepping tones at the full hour and half hour..
