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It's all getting out of hand!

October 4, 2016, 5:51 am
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Well,

A weekend at the National Hamfest plus a trip to LAM Communications has resulted in two new radios.... One is new and one is very second hand....

I've had to make another shelving unit to accomodate... that really is it now.... no more!

Local conditions.



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More 23cm Power Required!

October 14, 2016, 11:39 am
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Well,

The other night, there were a few of us trying out JT65C on 23cm. I could decode quite a few of the other stations but couldn't be heard. This is no surprise as I was using only 10W out of my IC-9100.

Quite a while ago I bought a 23cm PA module from PE1RKI - now this is a fairly serious bit of kit that I hadn't got round to doing anything with - until today.

I also bought a number of other items to go with the PA including a case, a switch mode PSU and a Ultimate Amplifier Control Board from W1PQL.

I built the control board and here it is just being attached to the rear panel of the amplifier case:


So the first thing in this kit board is a sequencer to handle all the different things we need to switch as part of going from TX ro RX and back again in a linear amp.

There's an ALC output -ve voltage to keep RF at nil from the driving radio, until such time as all the relays have gone clunk. Once that's happened the -ve voltage is removed and the RF allowed to flow.

Secondly there's a sequencer to drive the TX and RX co-ax relays plus turn on the main DC supply to the PA and it's bias. I have taken the advice from W1PQL and switched both the main DC supply and the bias off during RX. The main DC supply is switched by an external FET switch and the bias by an external relay as the current requirements of this amp are too high for the board to switch alone.

Here;s the SMPS I am using or the amp; it delivers 28V (it's a 24V unit with a pot adjustment) plus a separate 12V output. I can't remember the current rating but this amp needs 11 Amps at 28V so there should be more than enough here.


In the image below you can see the bulkhead N-Type connectors for the outside world, the control board, the external FET switch and the N-Type relay on the amp output. There's an SMA relay on the input which you can just see the side of on the far left of the picture. The second image shows the SMA relay much clearer.



Here's a close up of the innards of the amp itself:





Now, the control board would also control a fan based on a thermistor input - however I'm just wiring the fan on permanently in this build. It would also take a feed from a directional coupler and switch the amp off in the event of high SWR on the output - a most excellent idea - however, I don't have a directional coupler that will work at these frequencies so I guess we are going to risk it....


Chopsey AKA Bastard Cat from Hell hasn't helped much today:


Local conditions.
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Wow - It's working then?

October 19, 2016, 7:40 am
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Well,

A couple of updates for you.

Firstly I ordered a 13cm 44 ele antenna, which duly arrived:

I suspect this one is designed for beaming round corner:

Not very clever!

Secondly, I was looking at my 6M logs recently and decided to create a map of my 6M contacts:


I just need that elusive USA opening!

Here's the 23cm amplifier I mentioned back here. It's finished now - I tried it on the air last night in the UKAC and received some good reports:


It's even wired quite neatly inside:


Cabinet feet and everything:

I'm really quite pleased with this. Local conditions.
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Tripping over SWR

October 21, 2016, 11:54 pm
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Well,

I've been thinking some more about the linear for 23cm I started back here, and more importantly how I can generate a high SWR trip signal for the control board.

I have one of these directional couplers:


It has a forward and reflected port at -30dB. Then I remembered I had one of these kits, which built looks like this:






This will turn the sampled RF into a -ve DC voltage for the SWR trip on the control board.

Now, fortunately or unfortunately we now need to do some maths to determine the attenuation needed. The RF detector board contains two samplers, I have configured one for the forward power and one for the reflected.

So, starting with the forward port:

Assuming a maximum output from the linear of 150W, we can convert that to dBW using:

So my 150W RF becomes 21.8 dBW. Therefore the maximum power at the forward port of the directional coupler is 21.8 - 30 = -8.24 dBW.

Given that the maximum input power to the detector part of the board needs to be 3mW or 0.003 W we can also calculate that 3mW = -19 dBW.

Therefore I need an attenuation of the difference which is roughly 16dB.

Then assuming a trip level of 1.8:1 (or about 10dB return loss) the reflected levels need to be 10dB down from the forward so an attenuator of 6dB is needed on the reflected port.

Using my signal generator at 1,000 MHz (1 GHz) and adjusting the output we find this is the response of the board:


So it all looks pretty good.

I now need to do some reading up on how I can drive the trip alarms on the control board, but this should do the trick nicely.

Here's the dogs doing what dogs do:


Local conditions.


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Microwaves - now that's really nuts!

October 23, 2016, 4:50 am
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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?
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The SWR tripping issue

October 30, 2016, 9:20 am
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Well,

You may recall that back here I was starting to construct the SWR trip mechanism for the 23cm linear I built back here.  I've finished this and tested it today; as soon as the RF level on the reflected port reaches 10.8dBW my amplifier trips.

It looks like this in reality:


The return loss bridge is connected to the ANT socket of the linear and the forward and reflected ports are connected back to the amp box with SMA leads. Inside the box is the RF detector board that converts the RF into a -ve voltage and that has been adjusted in accordance with the calculations I did back here. So assuming the maths was correct I the linear will now trip if the SWR exceeds 1.8:1.

I also note there is good propagation on 2M today; looking out the window I see slightly misty but very still weather, often a sign on tropo:



The situation with Chopsey (AKA Git Bastard Cat from Hell) using my desk as his bed is now completely out of hand:



Florrie the ham cat has also taken to sleeping terribly close to my nixie clock which I am very fearful for:


Local conditions.
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4.4GHz Signal Generator - Really?

November 28, 2016, 9:52 am
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Well,

I attended the GMRT event this year, one of the highlights was seeing this in the flesh:


I also spotted a great project by GM8BJF which was a great signal generator covering 35MHz up to 4.4GHz using very cheap Chinese and eBay sourced components.

Here are the bits, firstly a ADF4351 evaluation board:

 


Secondly, a CY7C68013A development board:



And finally a broadband amp module:



Total cost of these three modules delivered was less than 45 GBP.

Now, I've tried two ways to drive the ADF4351, firstly using some excellent software from F1CJN - this worked very well and would make an excellent stand alone sig gen.

However, I have decided to replicate the project by GM8BJF exactly and use the three boards above together.

I followed the instructions on his website and have programmed the EEPROM on the CY7C68013A board and am now using the software from Analogue Devices from my PC to set the output frequency:




This software controls the ADF4351 from a PC using a USB connection and allows you to see all the register values and fiddle with all the device config - most excellent!

Here's a quick shot of the spectrum analyser connected to the output with the device set to 1.2GHz:


This is an appalling picture of the boards under test:


And here, Miss Florrie Cat assisting:

Neat, egh?


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JT4F - Really?

December 1, 2016, 12:09 am
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Well

A bit more Wednesday night activity on 23cm digital modes; last night I worked Neil, G4BRK on JT4F, here's how it looked from his end:



And this is from my end:



Now, two main observations:
  1. There is simply loads of Doppler or other effects - probably due to Aircraft Scatter / Reflections
  2. The report I sent was received with an additional "000" on the end - I wonder why
But the decodes of this mode seem extremely reliable in the presence of  multiple reflections - which makes it ideal for this kind of frequency.

Good, egh?
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Boxing Time

December 7, 2016, 11:02 am
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Well,

You may remember the 35MHz to 4.4GHz signal generator made from cheap eBay components I was fiddling with last time.

I've stuck it in a box now:



I've removed L1 from the board:



so that there is no power to the on-board 25MHz XO. I'm running mine using the shack 10MHz frequency standard I made back here. This external oscillator input simply connects to the SMA socket on the back of the board.

I've recently made a distribution amplifier for the frequency reference so  I have 8 50R outputs at 10MHz to lock a recently acquired Microwave frequency counter and also my HPO signal generator.

Good egh?
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Counting all the way to 13cm

December 8, 2016, 11:48 am
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Well,

You may have realised that I had something in mind when I made the Signal Generator up to 4.4GHz recently? Well, the idea is to use that to test a new transverter I have for 13cm:


This is another most excellent piece of kit from SG Labs. You may remember that the transverter used in this 23cm project came from the same place.

So, this transverter has a number of options for the LO, but with that set to be 1870 MHz, and my new Signal Generator set at 2301 MHz:



Lo, and indeed behold, on 431MHz we see a strong carrier:


Now, this transverter even came with a PCB antenna for 13cm:


So, the next thing is to try and test the TX side; not too sure how I am going to manage that yet, but I am sure I will find a way!

I have an ultra low noise amplifier from G4DDK ready to construct also for this band, plus a surplus telecoms PA block that should give some power. I also seem to have a 13cm Wimo antenna sat on my desk:



So, lots more to follow on this topic!

Local conditions.
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23cm Tap, Tap, Tap

December 10, 2016, 10:56 pm
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Well,

The other day on my travels I cam across a TS-2000X. Now, you may recall my declaration of No More! on a recent post. That didn't last long - did it?

Here's the radio:



As it's the X model it includes the 23cm board, the idea now is to add a tap into the IF at 23cm so we can have a panadaptor running on the 23cm band.

So, we take it to bits.....



The 23cm module is underneath this metal plate:


and looks like this....



Now, the buffer amplifier for the IF comes from HUPRF, and looks like this and is stuck to the screening can of the 23cm PA using a sticky pad:


In the image above you can see the input connection in place. The distructions for the board recommend only connecting the screen at the board end; I found a cable from a GPS receiver that fitted the connector so have done it that way.

Here's how I have routed the output coax for the IF tap to outside the radio:


and here seen from the top:


And here you can see where the power is being sourced from - this is about 7.2V on RX (no power on TX). I got in a real pickle with my big fat soldering iron here and you can see flux all over the shop - it's quite a mess:


There's an SDRPlay connected to the output of the tap board.

I've got a PCB log periodic antenna hanging off the front of my recent 30MHz to 4.4GHz signal generator:




So I can now set this to output it's 20dBM at various parts of the 23cm band and see the results on the panadaptor (SDR Radio).  Here we have a nice quiet band with a carrier from my Signal Generator at 1296 exactly:

 
Florrie the Ham Cat has been assisting throughout:



Local conditions.
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So, your mixing what?

December 13, 2016, 10:17 am
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Well,

I mentioned in this post that I needed to find a way to test the TX of my new transverter.

I've bought myself one of these:


It's a mini circuits mixer, that is rated to 2GHz but probably works to a fashion well beyond that. Electrically it looks like this:



So, as a test I have my new USB signal generator set at 2000 MHz connected to the RF port.





The HP Signal Generator from here is connected to the RF port and set to 900 MHz.

Now, given that this mixer should do what mixers do, the IF port should have the sum, the difference and all associated other components and harmonics:


The main point here being that 2000 MHz - 900 MHz = 1100 Mhz, which is clearly visible on the spectrum analyser.

So if I take the output of my 13cm 2.3GHz transverter and do some jiggery pokery with attenuators and then mix it with my 900 MHz sig gen signal I should be able to see it on my spectrum analyser at 1.4 GHz.

That should work, egh?
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Measuring 13cm

December 21, 2016, 6:00 am
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Well,

Following my previous musings here and the RX tests I have done on the 13cm transverter, I had a bash at testing the TX function today.

I found a frequency counter and RF power meter on my travels recently; Its an XL Microwave counter that measures up to 20GHz.

I've cobbled together a directional coupler from Narda, a Marconi 20dB attenuator plus a further 15dB reduction from another on-line purchased coupler. All in all the frequency measurement point should be about 35dB down from the actual output from the transverter.

It all looks like this:



Using the new meter and counter I am measuring exactly 2301 MHz and a power of -2.8dB:


So assuming my 35dB of attenuation is there or there abouts, that means the output of the transverter is about 32-33dBm which is about 2W - exactly on the money.

My analogue power meter also reads about on the money too:



I've also taken the -30dB forward port from the Narda directional coupler, mixed it with my 900MHz frequency generator as described back here. This has allowed me to see the output from the transverter at 2301 MHz - 900 MHz = 1401 MHz:

All good, egh?

Here's our beautiful Pepper Cat:



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QRSS Beacon

December 21, 2016, 6:40 am
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Well,

Earlier on today I dug out an old QRSS beacon that I made for 30M. I plugged it into my 30M dipole and switched it on.

I've just found this on the internet:


This is from the live grabber belonging to LA5GOA, here I have annotated the image to highlight my callsign in the grabber:


The beacon is running about 6V Peak to Peak which is around 100mW. Clearly I need to turn the power down.

Local conditions.
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Sequencing Secrets

December 26, 2016, 9:35 am
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Well,

I've been thinking some more about the 13cm project I have on the go, more importantly how I am going to arrange all the bits together.

Firstly we have a 13cm VLNA from G4DDK. I've started the build of this project - this is extreme soldering! the bits are very tiny indeed.

Here's where I am at with the project, unfortunately the last chip cap has made a bid for freedom and is in the carpet somewhere. Here partially built:


and here, almost complete all bar the input components:



Now, I also have the transverter from back here plus a ex telecoms PA that I will start to modify later.

I've started to draw the setup, to save on relays, switching and the associated losses, I will run separate feeds to the antenna (or masthead) for TX and RX. Also, due to the complexities associated with bias-T at these frequencies I will also feed power by cable.

I think it needs to look something like this:


So the thing labelled "gubbins" in the diagram above is actually a sequencer. Having built my 23cm amp back here utilised a ultimate amp control board from W6PQL, that included a sequencer and I had the schematic. So I drew this using non SMD components:


In reality it looks like this once built:


Looking at the top of C1 with a 'scope and grounding the D1 PTT line, we see this:


and as the voltage in C1 rises so the difference between the inverting and non-inverting inputs of the four op-amps swap in sequence as the voltage climbs to the power rail. Here you can see the output state change of the Event 1 op-amp in blue against C1 in yellow:


Event 2 happens later and then event 3 and 4. You can also see that they revert back in the opposite order as the voltage in D1 falls when the ground is removed from D1 and the capacitor discharges through D2 & D3.

Here's the timne delay from PTT to Event 1:


Those in the know tell me that these coax relays can bounce, so a delay of 200ms or more may be needed from thr relay power being initialised to any RF heading that way.


More to come!

Local conditions.
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More Sequencing Secrets

December 27, 2016, 2:42 am
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Well,

I've added a FET switch to the sequencer I made last time. The FET switch will provide +12V on RX to the masthead and will be used to switch the masthead relay and also power the VLNA.

The schematic looks like this:


and it's built on the same bit of veroboard as the sequencer:



It switches very quickly, here in blue is the PTT being enabled and in Yellow the power supply that will head up the mast:



So we will then have 200+ ms delay before EVENT 1 from the sequencer:


which will be used for things like turning on the PA bias and enabling RF 'n' stuff like that.

All in all this is coming on nicely.

Local conditions.
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Top Band (Again)

December 28, 2016, 11:49 am
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Well,

A while ago we had some work done in our garden, this resulted in the removal of a 'purglar'; now, this was all fine except it was supporting my top band antenna I made back here.

I've got round to making a replacement for the antenna today, nothing original - it's an end fed sloping, inductively loaded wire.

There's 54 feet of wire, 20 turns on a bit of tumble dryer vent pipe, then 5 feet to an earth rod (well two actually). Here's the inductor:


and this is the earth arrangement:






Now, I am planning to add several long counterpoise wires, but I haven't done so yet. I connected the antenna to my analyser thingamabob:

or if you prefer return loss:





I've been listening on the WSPR frequency tonight:




It will be a very inefficient antenna and also it has a very narrow bandwidth (like all inductively loaded antennas), but it's clearly hearing signals.

Here's a map after an overnight run:

 

I also took down the main 4M and 6M antenna today for maintenance, I've put somthing I had at the back of the shed in it's place temporarily, I've also put the 13cm antenna I had lying on my bench in the air:




Here's our two doing what Spaniels do on a beautiful frosty morning earlier today:



Good, egh?
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Busy, Isn't it?

December 29, 2016, 9:49 pm
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Well,

Following my Top Band anteanna from last time, here's a WSPR map:

I find it all rather hard to believe.

Local conditions.
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The VLNA, Oh Boy!

December 31, 2016, 8:42 am
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Well,

I think I have finished the build of the VLNA for 13cm; having constructed the project I am wishing I had bought a ready built and aligned unit. This was the hardest project to date, mainly because of the very tiny components. I really struggled to get the input matching network parts in place - and have no test gear to actually measure the return loss or noise figures of the final build.

It looks like this:









You can see the input network components in the image above; it kind of looks like the instructions from G4DDK @DXING, but I have no means to actualy measure or test the input return loss.

Lets see.
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AVR dude - really?

January 15, 2017, 2:07 am
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Well,

Over the past few months or so I have been playing with kits from QRP Labs based on the genius of Mr Hans Summers.

I was using the VFO I made back here to clock my newly built Signal Generator from here and found some rather odd behaviour.

When I investigated this I found that the VFO output switched off every second:


I posted on the QRP Labs forum and very soon had a reply telling me this was an issue that had been fixed in a later version of the firmware.

So now I needed to re-program the AVR processor using the hax file available - I hadnt done this before.

So, here you will find that you can use an Arduino as an AVR Programmer - now I have lots of those. On the Arduino site you can see how to configure the processor on a breadboard:

I added a 7805 regulator and powered the breadboard contents from my local bench PSU. I connected the grounds together of the Arduino and breadboard, but not the power lines! So the Arduino is powered from the USB cable and the breadboard separately.

So assuming you already have an Arduino IDE installed and working here are the steps:

  1. Start Arduino IDE and load the ArduinoISP sketch and upload to your Arduino (the sketch is in the examples folder and my board is an Uno)
  2. Wire the Arduino board as the above diagram - I used a 20MHz crystal and 2 22p capacitors
  3. Download avrdude from here (I put my download into a local directory C:\Users\Mark\Downloads\QRP VFO)
  4.  Download the hex file you want to program from the QRPLabs forum files area 
  5. Open a command window in Windows (type cmd in the search box)
  6. execute the command "cd C:\Users\Mark\Downloads\QRP VFO" (replace my target with your local directory)
  7. then we need two AVRDude commands (replace COM13 with your Arduino COM port):
    1. To set the fuses: avrdude -P COM13 -b 19200 -c arduino -p m328 -v -e -U efuse:w:0x04:m -U hfuse:w:0xDF:m -U lfuse:w:0xF7:m328
    2. To program the flash: avrdude -P COM13 -b 19200 -c arduino -p m328 -v -e -U flash:w:VFO.s1.02c.hex (replace with your hex file)
Here's what it all looks like on the bench (which is rather a mess):


Here is our very beautiful Miss Luna Cat who has been with us since July 2015, and is now, finally, letting me stroke her. She is asleep in the shack on the bag that cam with my recently acquired frequency counter:

 Local conditions
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