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A Starter for 10 GHz

August 26, 2015, 12:22 pm
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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.
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Testing RX - Starter for 10GHz

August 27, 2015, 2:52 am
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Well,

Following my last post here about my 10GHz setup:

Starter for 10GHz

Here's a quick video of the RX test:


Local conditions.
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Another Windom, Really?

September 11, 2015, 11:13 pm
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Well,

Having been thinking a little about my antennas I decided to take down the wire dipoles I have for 40M and 30M and try and squeeze in a full size Windom. It has fitted in the garden but the configuration is a little strange! It's kind of in a square where the feedpoint is in one of the corners.

Here's the dimensions of the antenna:


And here are the SWR readings I am getting in the shack starting at 80M:

40M:
30M:
20M:
17M:
15M:
12M:
10M:

So, all in all it looks quite promising! Time will tell as band conditions have been appalling over the past few days.

Here's a picture of our Elmo as he returned from the groomers yesterday - he was suitably unimpressed!


 Local conditions.
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Baluns - Yet Again!

September 14, 2015, 11:01 am
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Well,

Part of the Windom I made last time here was a 4:1 balun. Now I tested one of those way back in time here. Back then I didn't much like what I saw as the frequency increased - it looked like the balun was only good to about 4MHz.

I came home with one of these the other day:


I bought in from LAM Communications in Barnsley.

Now, I repeated the tests I did way back when on this new balun and got more or less exactly what I expected. Here I am inputting a signal at 2MHz into the balun and looking at the two signals out. My expectation is that these two signals should be 180 degrees out of phase, as they are here:


The yellow and blue are the two outputs and the purple the difference between the two.

Now, as I increased frequency the last time I tested a balun this picture got very much "out of bonk" (a technical phrase meaning broken) with the phase difference between the signals moving significantly. On this balun all seems well at 25MHz and higher:


So - this balun seems to have good performance over the advertised range of frequencies - much better than the last one I tested!

As a consequence this is the balun installed on the new Windom.

Local conditions.
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Windom Test - Shhhhh

September 15, 2015, 11:01 pm
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Well,

Following the build of the Windom Antenna, I wanted to see if it was functioning, my primary band of interest was 80M. I left the TS-590 WSPRing on 80M last night and here is the result:


Looks like it works.

Local conditions.
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More Testing - Starter for 10GHz

September 27, 2015, 12:17 pm
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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?
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Nearly Done - Starter for 10GHz

September 28, 2015, 10:19 am
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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.

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A Starter for 10GHz - RX Test

October 1, 2015, 5:39 am
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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.
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Its a funny old world

October 14, 2015, 12:02 pm
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Well,

I have a good relationship with the chaps at LAM Communications in Barnsley. I received a parcel from them today which was addressed thus:


Which was fairly amusing....

I have also recently done a video for them on Digital Modes and the FT-991 which can be found here:


Good egh? Local conditions.
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Well, What did you win?

October 16, 2015, 8:56 am
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Well,

Look what's just come through the post:


Local conditions.

Good, egh?
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Antennamabob Swap

October 22, 2015, 4:10 am
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Well,

Having played with the antenna I installed back here  for a while now, I have decided to go back to the Cushcraft MA5B that I had previously.

I have found that the Q52 antenna had little or no front to back, furthermore there was a switch on the control box that was supposed to "remove" the reflector to make the two element antenna into a dipole, whilst this altered the SWR very slightly, I found no difference whatsoever to signal strength from the front or the back of the antenna. Extended tests in both dipole and beam mode showed no signal strength difference from the front or the back of the antenna. Tom, N6BT, for reasons only be-known to him, chooses to ignore my email requests for technical support - so I haven't been able to get any. I did climb a ladder and conferm that I could hear the relays going click in both the director and reflector when the band switch was altered on the control box, I also double checked the control box to antenna wiring - not sure what else I can do to test the setup.

More recently, 500W of CW to the Q52 antenna has caused the relay box on the driven element to fail. Investigation shows that there are signs of arcing on the element connections - this antenna has proved to be a very expensive mistake!

I have also been having some concerns recently over the amount of weight on the mast and it's ability (or inability) to hold everything. I've therefore designed myself a new mast arrangement, there is no telescoping in this design, but it's much stronger and sturdier (and heavier) than the previous arrangement.

Here we are in the midst of the swap:


The Base section of the mast is 2.5 inch, thick walled box Aluminium, and that is then topped with a 48.3 mm OD stainless steel tube to the rotator cage. The stainless tube drops into the box section with a 2 meter overlap - the two items are bolted together in opposing angles so it can't move or turn. The rotator cage is made from galvanized steel and was manufactured by Tennamast. The stub mast is currently a 48.4 mm OD steel scaffold pole, but I have ordered a 3 meter long aluminium replacement to try and reduce the weight a little.

The mast all pivots and is lifted into the vertical using a winch and steel cable.


Once I have the replacement stub mast I will put back the VHF antennas and all will be well. The rotator is a replacement and is the G-1000 from Yaesu.

Here are the SWR curves from the MA5B as installed:





local conditions.
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A repeater, Really?

October 24, 2015, 11:13 pm
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Well,

Whilst musing at the recent HamFest myself and my chum Vince, G0ORC decided it might be a good idea to learn something of the new System Fusion technology.

Having studied a repeater coverage map and concluding there was nothing near us, we decided that the best thing we could do was to put a repeater on the air.

This started the application process for GB3BP a 70cm System Fusion repeater.

We spoke to our friends at LAM Communications and they agreed to sponsor the repeater and provide the Yaesu DR-1XE we need.


So far we have frequency clearance for Input 438.4875 MHz and Output 430.8875 Mhz, and we are waiting for the NoV from Ofcom. We also need to purchase a Duplexer and it's looking like this is the one for the job:

http://www.mixw.co.uk/CAVITY/MDF1-6-70cm.htm

More to follow, but we should be up and running soon.

This page includes the calculated coverage map which looks very pessimistic to me:

UK Repeaters

and here is a page I have setup for the repeater itself:

http://www.gb3bp.uk/

Fun egh? Local conditions.

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Repeater Filter

November 7, 2015, 1:07 am
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Well,

You may remember last time I mentioned we were setting up a repeater.

I've come home from some work related travels to find the duplexer for the repeater at the house. It looks like this:




I've hooked it up to the spectrum analyser to see what the frequency response looks like, here's the result:


It's impressive, isn't it?
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Shack Move!

November 15, 2015, 10:13 pm
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Well,

Do you ever take on a job and then regret it way before it's done? Here's my shack (old):




So it's basically destroyed!

Here's the new taking shape:





Cats already playing "shelf swat":


Local conditions. 
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MB6GX - Experimental Wires-X Node

November 17, 2015, 8:45 am
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Well,

In my new shack I have set up a dedicated Wires-X internet gateway.

I hold two internet gateway NoVs; MB6GX for 2M and MB6IGX for 70cm. As the 70cm NoV stipulates that there is no unattended operation allowed (not even if I am in the house but asleep), I have opted for the 2M Node.


So, MB6GX is on-air and is an experimental Wires-X node in IO93GA on 144.8375 MHz; reports very welcome.

Fun egh?
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Progress, Really?

November 30, 2015, 9:01 am
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Well,

I've concluded its tricky being DIY Dan whilst popping back and forth to Singapore. No matter how many times I travel, the distance and time zones do me in considerably!

The new shack is finally taking shape:



Some new bits n bobs too, new 'scope:


And also found this old Marconi Powermeter on my travels:


This was complete with waveguide to N-Type transition, attenuator and power head. A very nice addition to the test gear setup here. All I need to do now is learn how to use it!

Local conditions...
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Well, Well, Well, what's news?

February 2, 2016, 8:53 am
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It's been quite a while since I updated my blog, and there's been quite a bit going on in my life. Primarilly I have been travelling to the Far East and back working for a living.

We've also had a new addition to the family, this is Bonnie Dog, she is the daughter of our Elmo and is a Sprocker Spaniel:



She is 12 weeks old today and quite a bit bigger now than the photo above, here she is with her Dad:


The shack is more than complete and already a total mess nearly all the time:




Myself and my chum Vince, G0OIRC have started dabbling in the Tuesday evening UKAC contests.

We bought ourselves a generator:



Plus a selection of antennas to cover 6M, 4M, 2M and 70cm:


We have been operating from Alport Top in Derbyshire IO93FB:

So far, due to my travelling, we have only done one 70cm test, but the results were very impressive. We are ready for tonights 2M test, so we will see what happens:



We are also planning to get a 23cm capability for portable operation, my current plan is to combine one of these transverters:

http://www.sg-lab.com/TR1300/tr1300.html

with one of the PAs from here:

http://www.g4bao.com/

Fun egh?

Local conditions.
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UKAC - Up there, Really?

February 3, 2016, 3:33 am
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Well,

We had our second bash at entering a UKAC contest last night. Myself and my chum Vince, G0ORC headed to the top of Alport Heights in Derbyshire with a generator, some poles an antenna, a radio and other bits and bobs.

Station seemed to work well and we headed home after 100 contacts due to the cold, damp and generally miserable conditions. The site is over 1000ft ASL and it was snowing up there last night!
 
Here's a map of our log:


Which isn't as good as what we achieved on 70cm a few weeks ago:


Now, the results are out for the 70cm test from January here: Results and it's clear we made quite a few errors in our operating and also logging. We are currently keeping a paper log and then transcribing it to electronic after the contest - there were some mistakes in the transcription too!

This is the result of the log analysis:

So all in all we have a 3/10 must do better!

Local conditions.

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23cm - From a hilltop?

February 8, 2016, 10:49 am
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Well,

I mentioned a while ago that myself and Vince, G0ORC were planning to have a bash in the UKAC contests. We have a capability for 6M, 2M and 70cm but nothing portable yet for 23cm. So hence the project....

I bought one of these transverters:

http://sg-lab.com/TR1300/tr1300.html

and to go with it a PA kit from G4BAO:

http://g4bao.com/

Here's what I've made so far:






I used a toroidal transformer I had to create the PSU, the requirements are 28V for the PA and 12V for the transverter.

The transverter module itself looks like this:


and the PA, once constructed, looks like this:





Now, the first conundrum was how to test the RX path of the transverter given that my signal generator only goes as high as 1GHz.

What I realised was that my Spectrum Analyser can be set into zero span mode and that makes the tracking generator a fixed frequency. So I set the Spec An to 1296.5 MHz and hooked it up like this:




With the F-817 set to 144.5 MHz I have a strong carrier - so I conclude that the RX chain is working.

Now to test the TX chain - more tricky!

First of all I realised that I can tune the input and output of the PA using the Return Loss Bridge combined with the Spectrum Analyser. Here's the finished result on the input side (after some trimming in accordance with the assembly instructions):


And here is the output side of the PA:


So now to devise a way to test the whole TX chain, this is what I came up with:




Which kind of looks like this:


So we have the RF from the PA into the big block which is a Return Loss Bridge, the -30dB port is feeding the Spectrum Analyser via another 25dB attenuator, then on the antenna side we have 2 x 30dB attenuators to a 50 ohm load. The return loss of this lot is actually quite good and looks like this:


Now, I have tested the transverter without the PA and can see an output at the expected frequency:


There's much less attenuation in the chain for the test above, but when I try and set the idle current on the PA it kind of runs away. By that I mean that as the device heats up so the current drawn increases and just keeps increasing. I think this is because I don't yet have any suitable heatsyncing in place so have ordered something which I will have to wait for before I can continue.

So far, so good though, egh?

Here's our latest addition currled up with her Dad:


Local conditions.
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23cm - From a Hilltop - Oh Yes!

February 13, 2016, 3:16 am
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Well,

You may remember last time I was rambling on about my portable 23cm project; well I had come a little unstuck with what looked like thermal runaway in the PA block.

I managed to acquire a suitable heatsync for the PA and then had another bash at setting the idle current at the 350mA recommended by the PA designer. Eventually, after much trial and error I got the idle current set and there was no hint of the runaway I was seeing before.

So, I took a deep breath and hoked it all up ready for the TX test. The setup was the same as I described last time except I added a power meter at the output of the PA:


I've lashed everything down inside the case in my usual "bodge it and scarper" method and the birds nest now looks like this:


And the whole thing now looks like this:



I'm measuring about 50W output on the power meter, so that'll do nicely.

We've got this Wimo antenna ready for the hilltop which is currently strapped to my Wifes line post:


The return loss of the antenna looks just fine:


By my calculations, if we have 50W out of the linear, that's about 17dBW, the antenna claims 16.something dB gain, even if we call the antenna gain 13dB that makes the ERP about 1KW!

We need to make sure we don't cook too many passing pigeons with this baby.

Local conditions.
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