Tuesday, 19 February 2019

My Es-Hail update

Having now had several QSOs on the satellite narrowband transponder with parts of the system scattered around my shack and cable everywhere, I decided I really  ought  to rationalise the system in light of what I’d learnt.
The 5MHz OCXO based reference works well, so that is being retained. More on that in another blog.

Instead of combining the transverter and 25W PA in one large, weatherproof, Storno CQM case, initial tests have shown that with the antenna I am  currently using 1W is enought to exceed the level of the beacons, so the transverter goes in an internal 1U rack case with the 5>25MHz reference and a substantial 12V PSU.
A considerable number of bulkhead connectors on the rear of the 1U case bring in the 10MHz reference for the transverter (SGLabs), all the RF interconnectors for the transverter, including IF and RF input and output & PTT from the IF. Other connectors route the LNB IF coax through an internal link and back out, for later expansion facilities.
Also the 25MHz output to the LNB appears on yet another SMA connector.
The PSU is left on all the time, to power the 25MHz reference, whilst a substantial toggle switch is used to switch power on and off to the transverter and external 25W PA (via another switch to enable the PA, when required). See next day update on this PSU.
The LNB IF is routed to the operating desk where the 12v/18V polarisation switch PSU is located, together with a three way splitter for the Minitiouner, RSP2 Pro and the 738>144MHz downconverter.
I have done away with the separates (K3 and 144MHz transverter for receive IF and FT817 for transmit).
Whilst I wait for the IC9700 to arrive (it may have been delayed, from rumours about FCC acceptance problems around the recent US government financial shut down) I acquired a rather nice FT847 satellite transceiver at a very good price. This radio does full duplex satellite (it has separate IFs for transmit and receive) with normal or reverse tracking. This means just tune to the wanted downlink signal and as long as it is set up properly, the transmit is right on frequency. Nice!  It makes life so much easier. The IC9700 has the same facility.

I’ll cover the DATV side in another blog.

I started by using a HS 17.5dBi  flat plate antenna with the barefoot transverter and about 3dB of feeder loss. In other words, about 17-18dBW EIRP. My SSB signal was about 6dB SNR in 2.5kHz. This is a solutely marginal for comfortable SSB copy. I later discovered my transverter output was a bit lower than I thought.
However, I am going to provide the 25W PA as a switchable option in case it’s needed and to use with a few other antennas I want to try.

After the flat plate antenna QSOs I connected the transverter over about 1dB feeder loss to my 2.3m diameter EME dish with septum polariser 13cm feed for circular polarisation. I had to turn the power right down to stay below the satellite beacons!

Photo of the reverence/transverter case to follow.

Also the 25W PA on its separate heatsink.


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