There must be sacrifices to the god of performance! Has this happened to you, too?
MRF21045 – 2.2 GHz UMTS amplifier for retuning to 13 cm for QO-100
I started working with the Es’Hail-2 QO-100 satellite in 2019, but after moving to a new QTH, other obligations took priority. A step toward my return was building an IceCone radiator based on DC8PAT’s design. I tested it last summer. It wasn’t until this year that I was able to finalize the transverter with the amplifier into a compact unit. The amplifier received a new BIAS circuit. However, this led to a fault where, after disconnecting one wire, the amplifier with the MRF21045 received full supply voltage at the gate…
100 cm FTE parabolic dish with DC8PAT IceCone reflector
It’s a shame, because it happened right at the very end. My first idea was to replace the MRF21045 with a new one, but desoldering the damaged transistor from the heat sink and the circuit board proved to be a task beyond my capabilities and equipment. The second idea was to buy a similar used amplifier and re-tune it. Surprisingly, however, there were almost no listings online. The third option was to place the transverter in a waterproof enclosure right next to the illuminator. However, this option didn’t appeal to me very much.
And when a listing for a used amplifier did appear, the price was astronomical. Final decision: to purchase the SG Labs LZ5HP amplifier.
Hristyan delivered the amplifier very quickly. Both the transverter and the amplifier are superbly crafted. I was finally able to complete the setup.
Transverter with a 13 cm amplifier for the QO-100 satellite
Frequency response of the Behringer XM8500
Over the next few evenings, I made dozens of contacts. I’m using a Kenwood TS-2000 with a Behringer XM8500 microphone. It drives the transverter–amplifier–IceCone radiator chain into a 1-meter offset dish.
Reception begins with an unmodified LNB. The signal enters the RSP1a via a power splitter. The RSP1a is controlled by SDR Console, where I use the satellite’s center beacon for stabilization.
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TIP: Synchronizing QO-100 tuning via CAT in SDR Console
By connecting the TCVR via CAT and entering the offset in SDR Console, you can ensure that the TCVR tunes in sync with the SDR. This is a very convenient way to tune. Temperature changes may cause the offset to shift, so you’ll need to readjust it if necessary.
TIP: Signal attenuation during transmission
I use the received signal attenuation feature in SDR Console while transmitting. This way, I meet the requirement that I can hear myself, but the level is low enough that it does not cause interference.
SSB Sprint Contest on the QO-100 satellite
On Saturday, October 5, I also tried my hand at an event called the SSB Sprint Contest. In just under two hours of operation, I made 42 contacts. Compared to other contests, there’s minimal interference here. My log includes, for example, 3X1A, CU2ZG, SV8/HB9FIH, etc.
Map of contacts in the QO-100 Sprint