Yet more on 3cm (10 GHz)

Well,

Following my efforts last time, I managed to get my hands on a 10GHz power amplifier (of sorts):


 This delivers a huge 1W out on 10368 MHz and requires 100mW drive.

According to the transverter manual, I need a sequencer to work this kind of set up properly:

It seems a little strange to me as the Transverter is put into TX first, then the changeover relay and then the PA. I would have thought the relay, PA then transverter so we generate RF last, but hey ho.

I did a quick design of a simple sequencer:

And here it is prototyped on the bench:


It was giving me about 500ms delay between the relay and the PA on TX:


and about half of that on TX Off:


So I made the circuit on some veroboard and stuck it to the top of the PA:


I also made a latching relay driver and bunged it all in a bigger box.


Now, I configured my XL Microwave power meter to read frequency and power and hooked it to the transverter output and adjusted the TX gain to give me 20dBm out. I then hooked that to the input of the PA.

I'm reading about 27dBm out on TX which is 3dB short of target (so half power!). The PA has a voltage point to measure TX power and the sheet that came with it says 2.7V is 1W out, I'm measuring more like 3.5V at that pin so implying that I am over-driving the PA. It's so difficult at these frequencies to know whats accurate and whats not. When I measure the output of the transverter I have to use a 20dB attenuation - I don't know how accurate that is at 10 GHz for a start! Then there will also be losses in the interconnecting cables; so it's all a bit of a muddle.

So I am suitably confused at the moment!

Here's our lovely Florrie Cat proudly sitting in an empty egg box:

Local conditions.