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Saturday, 24 August 2019

DVB-S2 - really?

A very quick special message broadcast on the QO-100 Digital Amateur Television:

Local conditions.

Saturday, 17 August 2019

Radio Analog PTRX-7300 - Really?


You may well have seen adverts for the PTRX-7300 from Radio Analog. This is some kind of new fangled adaptormabob for the Icom IC-7300 that gives you an RF output that you can hook up to an external SDR for a panadapter display.

Well, I ordered one.

Here are the bits that you get (but not the screwdriver):

You start by taking the radio top cover off:

Then we disconnect the cable that attaches to the rear external tuner connector and remove it:

Then the new gubbins clips into the space where the external tuner connector was:

Hook up the cable into the now vacated socket for the external tuner connector:

and then pull a plug out of the radio PCB and insert into the new gubbins:

Then we have a supplied cable from the new gubbins to the PCB socket we just disconnected:

And thats it! Now externally the tuner connector is re-connected and also a flying lead with an SMA connector to feed to the SDR. This is extremely neat!

So once we have all that done, I have set up SDR Console:

and it just works.


Tuesday, 13 August 2019

Up-converting - you what?


Further to the PA I made last time, today I have been finishing off the up-converter to accompany it.

The theory goes something like this:

  • The Portsdown will output DATV on 439 MHz through the transverter output
  • This will be sent down the garden in Ecoflex-15
  • The co-ax losses will be compensated for using the 70cm amp I made back here
  • This will feed the SG Labs transverter we played with back here
  • The output of the transverter is then boosted by the Wi-Fi amp from here 
  • Finally the output is fed to the PA
Here's the up-converter in its finished form, there's a simple sequencer in there to handle the PTT switching and send a PTT signal to the PA:

Tomorrow I hope to install this and the PA in the small shed I have near the dish - then for some on-air testing.

This is the output of the up-converter DVB-S, SR250, FEC 1/2 - received with an antenna across the bench:


I've not yet installed the equipment in the garden, so I have about 4-5dB minimum of cable loss between the PA and the dish feed. However, here's my first RX of my own TV signal through Es-Hail'2:

** UPDATE 2 **

I've moved the gubbins to the small shed near the dish:

And am now sending 439MHz (ish) down the garden from the Portsdown.

This is a 333KS transmission via QO-100, you can see my signal on the left of the Mini Tioune software at 10,497.750 MHz:

And here is a testcard:

Local conditions.

Sunday, 11 August 2019

Even More Power!


I've been messing about and finishing off my 13cm linear. The idea is to make something that will work on the 2.3GHz amateur band frequencies as well as 2.4GHz for DATV on Es'hail-2.

This has been quite a challenge, but eventually we have something working ready for on air testing.

This is the final build, which even though I say so myself, is a masterpiece:

The PA module itself is something from my travels made by PowerWave:

There are five MOSFETS in total - each one is a SRF7068H5HS.

This is controlled by a W6PQL Amplifier Control Board which in turn uses an external FET switch to turn on and off the 12V bias lines to the PA, provide the sequencing necessary, generate an ALC voltage (just in case I need it later), generate an external PTT out for switching VLNAs or other external gubbins.

There's also a chassis mounted directional coupler (a NARDA model 31152) which provides a -30dB forward and reflected port output which is attenuated and rectified to produce a DC voltage. There's a forward voltage for a future power meter and also a reflected power voltage to activate a trip if the SWR should exceed 2:1.

I've even included a thermistor on the main heatsync and a trip in the amp control to switch on the fans or even shutdown the amp when over temperature.

I'm seeing about 26dB of gain from the amplifier and it will generate about 250W of CW on 2.407 GHz so should easily generate the 30-40W I might need for some DATV experiments.

Here is the unit under test, I'm using the Portsdown to generate a signal at 432.75 MHz, then using the mixer from the UK Microwave Group forum to mix in 1975 MHz to generate an output on 2004.75 MHz. This is then amplified up and fed to the linear. The forward port of the directional coupler (-30dB) is coupled via another 20dB attenuator to my XL Microwave meter. A short piece of coathanger shoved into the front of the Spectrum Analyser allows me to measure the harmonics and also look at the TX waveform.

A thing of beauty is a joy to behold! I'm delighted with this.