Completing 23cm

Well,

You may recall last time, I was changing my portable setup for 23cm. Well, on my travels I found a Kuhne Electronic PA for 23cm and have installed it in the waterproof enclosure with the rest of the gubbins:

I have a 14dB attenuator between the transverter TX output and the PA input. Thats a bit bigger than I need, but I don't have anything else suitable at the moment. The G4BAO amplifier that I now have here (thanks John) is going to get utilised as a DATV amp (I think).

I've been fiddling with a cheap Chinese board with a variable attenuator on-board. You can control this using the DIP switches on board or by software. I've written a very simple bit of Arduino code and interfaced an Arduino Nano to the board using serial comms:

This allows me to step through from 0-30dB attenuation in 0.5dB steps. Really quite neat for just under £12 GBP delivered from the far east! I may decide to use this to get the transverter to PA attenuation exactly on the money - let's see.

I'd like to introduce you to the best and most useful screwdriver in my possession:

This belonged to my Father who sadly passed away just over 31 years ago:

I'm often heard muttering to myself "now where's Dad's screwdriver". If it's of interest Dad, I still use it regularly!

Local conditions.

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 50mW 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 from here 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.

A Starter for 10GHz - RX Test

Well,

Myself and Vince, G0ORC headed to Alport today:

We aimed the antenna at the Leicester repeater GB3LEX on 10368.955MHz and here's what we heard:

It was rather foggy, but an excellent site that we will certainly visit again:

Whilst a very feeble distance:

This feels like one of my greatest achievements to date!

Local conditions.

Testing RX - Starter for 10GHz

Well,

Following my last post here about my 10GHz setup:

Starter for 10GHz

Here's a quick video of the RX test:

Local conditions.

A Starter for 10 GHz

Well,

Due to being rather poorly and  ending up having my thyroid removed, I've not done much in the way of radio.

However, for some time now I have been interested in learning more about the microwave bands and the amateur allocations we have in that part of the spectrum.

I attended a Microwave Roundtable event at Finningley ARS quite a while ago and met some very clever chaps who messed about at these frequencies. As a consequence I have been trying to create a "starter for 10GHz" in the background for a while.

The heart of the system is a transverter from Kuhne Electronics - this is a basic 144MHz to 10GHz transverter. To utilise this device you need a few ancillary bits to create a system, but mainly an antennamabob and a TX RX relay.

Here is the main transverter box with the other bits and bobs completed:

You can see the TX/RX relay - this is a latching RF relay which is fired from 12V using the circuit on the veroboard you can see. There is a BNC socket for an external 10MHZ signal; conviniently just like the one I made here: GPS OCXO, there's an SO239 for the IF (which is 144MHz) plus a line from the IF radio for PTT. A couple of LEDs and that bit is complete.

I managed to find two different antennamabobs for 10GHz, there's this one:

and this one:

I also bought myself an old satellite dish of eBay for £10:

So with a little bit of metal bashing and a speaker tripod, I have ended up with this:

I have simply mounted the smaller of the two 10GHz horn antennas in the same place that the LNB was when I got the dish.

Now, how on earth do I test this???

I will be using my FT-817 as the 144MHz driver and receiver, but I have no test gear for these frequencies so generating a signal to test the RX was going to be tough.

In steps Kevin, G3AAF. He has done some very clever things with a common bluetooth module using software and has come up with an RF source which can be used as a kind of home beacon/test RF source. It's called BTThing:

I've added the box and an PCB antenna from Sam, G4DDK:

So this set to 2592 MHz will give me a harmonic in the 10 GHz band at 10,368 MHz; and lo and indeed behold I can hear this signal on my setup.

I haven't yet tried the horn and dish combination but will set up a test area somewhere in the house tomorrow and give it a whirl.

I've had a kind offer of some elmering in these matters from Peter, G3PHO so I should be able to test this out fully when he has some time.

Here's our Elmo dog for a change:

Local conditions.