3cm Learning

Well,

Ween up a big hill today to play on 3cm:

Pretty nice day in my bit of England:

Here's a video of the Finningley beacon as RX today:

Here's what I learned today:

1. The beam heading on the dish is extremely sharp;
2. I need a more accurate way to determine beam headings;
3. I need a way to turn the mast whilst also tuning round on the radio;
4. The fitting of the mast into the base is a bit loose; the pole isn't completely vertical

All in all, 3/10 could do better. But I have made QSOs now on 10GHz and that feels like a great achievement.

#GHzbands

Here's Miss Pepper, assisting as per usual:

Finishing 3cm

Well,

Following my musings back here, I've finished the portable 3cm thingamabob:

I've moved the sequencer to be on top of the transverter box and added some surplus heatsyncs to the PA module.

I've even made a metal sheet and drilled it so it all fits on the arm of the dish.

I've also been up to Alport Heights today to test the portable 13cm setup:

Here's a clip of the reception of GB3ZME from the top of the hill:

#GHZBands

Good, egh?

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.

3cm Again

Well,

You may recall my adventures back here on 10 GHz.

Well, today I have decided to resurrect the project and see what happens if I put a dish up on the new mast.

So I got myself a waterproof enclosure, and re-housed the gubbins:

I also have a new mesh dish with a 1M diameter:

Theory says about 37dB or so gain.

I have to pop to the Middle East for a few days, but will get this up in the air when I return.

Here's my very lovely Luna Cat at home in the shack:

Good, egh?

Microwaves - now that's really nuts!

Well,

Following the build of my amplifier for 23cm here. I've been involved in some on-air tests of the JT modes on 23cm.

Here's a screen shot of my signels on JT65C as received by Tony, G4NBS in JO02af (Cambridge).

You will see multiple signals at times and we are sure this is due to Aircraft Scatter - I was seeing very much the same kind of thing on RX also. Anyhow, I am pleased to have logged 23cm JT65C QSOs with G4BAO. G4DDK and G4NBS.

I've been back up to Alport Heights in Derbyshire today with my 10GHz equipment from back here.

And have been listening to GB3FNY on 10,368.752 MHz:

I can find no trace of GB3LEX on 10,386.955 and can only assume it's off air.

Bonkers, egh?

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.

Nearly Done - Starter for 10GHz

Well,

The final parts have fallen into place today. Firstly I have adjusted the HB100 from the ARRL $25 10GHz signal generator I mentioned last time to be as close to 10.368 GHz as possible using the LNB range extender for the Spectrum Analyser (also from last time).

The metal case contains a grub like screw underneath a QC sticker. Here you can see the device with the QC sticker removed. As luck would have it the trimmer for the coils in the transverters fits perfectly - you just turn the screw to adjust the frequency:

The other thing I have done is construct an interface box for the FT-817 to:

• Putting the 3cm transverter into TX by sending DC up the IF coax;
• Providing a AFSK digital mode interface from my laptop;
• Giving a CW keyboard capability.

Here's the schematic:

Please note that the 'DC up the coax' bits are entirely stolen from here: http://www.g3pho.org.uk/

The actual device looks like this:

and it interfaces to the FT-817 through the two rear sockets for ACC and PKT.

So all in all I think I now have a CW, SSB and digital mode capability on 10 GHz.

Local conditions.

More Testing - Starter for 10GHz

Well,

You may recall a while ago I started a microwave project called "A Starter for 10GHz" and I did some basic testing of the RX here. Today I have been to visit Peter, G3PHO and his amazing emporium of test gear; together we have tested the TX side of the project successfully.

I've done a few other things since I came back from visiting Peter - the first being to devise a way to get my DC to 1.5GHz spectrum analyser to display 10GHz signals following some excellent inspiration from Peter.

Here's a picture of a eBay purchased LNB:

This device is very high specification and uses a PLL local oscillator, here's the spec (in German) from the box:

So basically it's designed to receive 10.7 GHz to 12.75GHz with a local oscillator of 9.75GHz. If you inject a tone to the DC supply you switch to the 10.6 GHz local oscillator also available, but we don't want that for our purpose.

Now, I've made a very simple Bias-T to send some DC up the coax feed to the LNB:

and used this to connect the LNB to the input of my Spectrum Analyser:

 

Very much inspired by the ARRL $25 10GHz Signal Generator I purchased a couple of the HB 100 units from eBay for a few $s. I have added a voltage regulator plus a couple of caps:

This is switched on and running on the bench as is BTThing I told you about back here. BTThing is set to 2592 MHz making the 4th harmonic at 10.368 GHz.

The Spectrum Analyser screen looks like this:

The smaller peak to the right is BTThing. Doing the maths, we have:

Which is pretty damn close to the 4th harmonic calculation of 10.368 GHz.

Using a similar technique:

We can deduce that the HB100 $25 ARRL signal generator is on 10.345 GHz.

Local conditions. All good egh?

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.