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Monday, 15 December 2014

It Made it!

Well,

I mentioned a post or two ago that I had sold some things, and bought some things.

One of the things I sold was my good faithful FT-847 that I worked on back here:

http://g0mgx.blogspot.co.uk/2012/06/ft-847-pre-amp-installation.html

and the modified the PA back here:

http://g0mgx.blogspot.co.uk/2012/06/ft-847-pa-mod-theres-better-way.html

The radio has gone to a good home in Marcus, OH1MN in Finland. I have never sent a parcel abroad before, let a lone one of this kind of value. But today the radio has been welcomed in it's new home:


I am very pleased that Marcus is pleased :-)

So, my shack has changed a little. Since bringing the new FLEX-6300 home it became very apparent that I needed 2 monitors. Now, I haven't tried 2 monitors before so I assumed I would need a fancy graphics card that supported two.... so I bought one. But no! I don't need a new graphics card at all! I connected one monitor to the VGA port and another to the HDMI port and bingo! To separately controllable monitors we have. Some rearrangements of my test equipment and here we are:


So radios now are:


  • TS-990 (main rig and a most wonderful piece of equipment)
  • IC-7100 for 2M, 4M and 6M Meteor Scatter
  • FLEX-6300 for HF and 6M
I still have the main HF linear I bough back here:


but now there is also the Gemini linear for 4/6M (on the right in the photo above) and 2M. The 2M linear includes the power supply for the masthead preamp we made here:


It does now mean that my test gear is a little squashed and my Spectrum Analyser has been demoted to the windowsill (which isn't good):


But I can play with the layout some more another time.

Cat's not helped much, just watched mostly:


Good, egh?

Thursday, 11 December 2014

It's all in the Software!

Well,

I've finally decided to have a proper play with Software Defined Radio. I've bought myself a FLEX-6300, which looks dull and boring like this:


The software end of the radio is spectacularly impressive:


The box itself connects to the network I have in the shack, that means I can run the control software from either of the two PC's here, my laptop anywhere in the house and also from just about any remote location where I have internet access. I haven't yet figured out how to get the audio to and from the radio over IP but it is certainly possible.

I can run the control software on one of the PCs in the shack and (for example) connect to the radio using Ham Radio Deluxe from the other PC which can then also run the DM780 application for digital modes. I have got logger32 working successfully with the FLEX-6300 as it offers a standard "CAT" type of interface, I have also got the CW Machine to work but have had to build a simple interface between a COM port on the PC and the accessory connector on the back of the FLEX. I was rather hoping this would be all done in software and "virtual" com ports; but it seems not. This is the interface; the FLEX uses a standard VGA connector for it's accessory port so it was simple to interface against.


The control software includes a feature called "DAX" which is Digital Audio eXchange - it's a means to connect audio to and from the radio to other applications without going from digital to analogue and then back to digital again. That seems to work really well as I have managed to get a number of application (WSJT for example) working easily. There is also a separate piece of software to monitor and control the DAX channels; plus another piece of software for COM port management. You seem to be able to create "virtual" ports as "shared", "dedicated" or "PTT". I have only tried the PTT port so far, ans as expected it creates a virtual com port you can connect with using 3rd party applications and key the PTT line using the RTS line of the virtual port.

I haven't done much experimentation yet, but I understand there are a number of alternative software applications I can use to control the radio - so there is much to play with and find out!

So far my first impressions are excellent although there doesn't seem to be a way to run FSK based RTTY.

All good so far - agree?

Monday, 8 December 2014

The PTT Conundrum

Well,

You may remember a while back I described a PTT switching circuit to manage the PTT line to the HF linear, 4/6M combined linear, 4M transverter and 2M transverter and linear. Well, I changed it a little more tonight and added a selection switch so I can drive any amplifier/transverter from any radio. This is the original plan:


I've now broken the line from the TS-990 to the PTT select in the diagram above and added another rotary switch. The complexity is in the need to switch the 4M transverter and the 4/6 amplifier in one setting and just the 4/6 amplifier in another.

The unit looks like this now:


Not the most complex project I've ever tackled, here's the front of the case:


and the back:


and here is the finished article in position:


There's been a few other changes here, I've sold some things and bought some things. Tomorrow my new toy should arrive.... I'll keep you posted.

Local conditions.

Good, egh?

Sunday, 7 December 2014

How can something so Simple be so Tricky?

Well,

What a couple of days! I dropped the antennas down yesterday, the idea being to fit a Masthead preamp for the 2M antenna.

The preamp has been homebrewed, but I am sworn to secrecy as to it's design and origin. Needless to say, keeping an eye out here:

http://g4ddk.com/

May prove to be a most excellent idea if you happened to want one of these.

This is the basic board populated but still under test inside the house:


The board  gave me about 17.5dB of gain right across the 144-147 MHz range. This is a close up of the top of the amplification peak on the Spectrum analyser:


So I took the antennas down (which involves taking the closest element to the ground off the HF beam):


and I fitted the pre-amp. Now, this involved replacing the direct feeder to the beam and introducing a joint in the coax (so I can remove the amp if needed in the future).


So the preamp in in the waterproof box you see above, after many iterations I have the set-up working perfectly. I have, during the process, proved how completely incompetent I am at fitting N-Type connectors!  I've got there in the end though - only about a day and a half elapsed time!

All told though, a most excellent result.

Freddie has become exceptionally clingy to me since I returned from the Middle East earlier this week, hasn't helped much today though:



Local conditions.

Good, egh?

Sunday, 9 November 2014

I think we made it

Well,

Following on from all my transverting conundrums, I have finally finished the configuration today.

Here's how the setup is now configured:


It's been the PTT switching that's caused me the most confusion. I've ended up making a switch box containing a 4 way rotary switch that allows me to select 2, 4, 6 or HF. In the 4M selection position the PTT drives both the 4M transverter and the 4/6M linear, in the 6M position it's just the 4/6 Linear that's enabled.

I've written a load of Macros for transverter control that I issue using the Logger32 Radio Control Panel. Here's an example of the macro that takes the TS-990 into 144MHz transvert mode:

$COMMAND OM0D;$ Mode USB-D
$COMMAND FA00028370000;$ 28MHz VFO Frequency
$COMMAND XO000116000000;$ offset 116MHz +ve
$COMMAND XV1;$ transvert on
$COMMAND AN00911;$ DRV on and RX ANT On

My only disappointment is that the radio isn't including the transverter offset in the results returned from the "IF;" command. That's the command that the Logger32 software repeatedly issues to the radio to determine the operating frequency.

For example, when the radio is configured like this:


You can see that the Transvert option is enabled as is the external DRV socket (that is the 0dBm output signal to drive the transverter) plus the RX antenna is enabled.

When the "IF;" command is issued to the radio, unfortunately it returns 28.370.00MHz as the frequency.

That's a real shame.

Local conditions.

Thursday, 30 October 2014

Transverting some more, some more

Well,

Following my progress last time:

http://g0mgx.blogspot.co.uk/2014/10/transverting-some-more.html

I've kind of finished (ready for test) the Anglian transverter.

Here's the finished article:


Here's the main transverter module:


This is the external DDS LO which stabilises the in-board LO:


And this is my hideous looking changeover relay for the 144MHz socket.


There's an Omeron relay on the underside of the board, even so it looks pretty hideous to me!

These are the things I am not so sure about:


  • The case is metal but plastic coated. Have I got a good ground connection to the front, back and main parts of the case - should I add some specific earth tags on each part of the case?
  • The changeover relay - need I say more!
Fun though, egh?

Wednesday, 29 October 2014

Transverting some more

Well,

You may recall my discussion a while ago on the best way to get a 144MHz capability here; should I continue to use my FT-847 or transvert from my TS-990.

The TS-990 has an external drive socket "DRV" documented to be a 0dBm output; that's not entirely true. What I have found is that:

  • WITHOUT XVRT selected the output power on the DRV socket is variable from 0dBm to -15dBm with the front panel power control.
  • WITH XVRT selected AND Advanced Menu item 8 ON the power is fixed at -15dBm.
  • WITH XVRT selected AND Advanced Menu item 8 OFF the power is variable between 0dBm and -15dBm with the front panel power control.
However, the TS-990 also has a neat feature in that you can program the offset of the transverter into the rig, thus making the display read the transverted frequency rather than the IF.

So, I joined the list for an Anglian transverter from Sam, G4DDK:


And after seeing him present the design at the RSGB HamFest, mine duly arrived.

Here's the basic transverter module in its screening box:



And the underside:



This will be stabilised by an external 116MHz Local Oscillator generated by a kit from ZL2BKC, based on an Analogue Devices ADF4351 DDS:

you can find details of this project here:


Then finally, there is an 8W PA module for the output:


This is based on the Mitsubishi RA08H1317M module. I've cut the input track and made a 6dB pad at the input on mine:


I haven't yet assembled the PA module, but I have made the heat spreader that the board is bolted too.

The next job was to build and test the low pass filter for the amplifier output stage, it looks like this:


It's pass band looks like this:


and the return loss like this:


All in all, the 2M transverter project is progressing nicely.

Pepper cat hasn't been helping much:


Fun, egh?

Saturday, 4 October 2014

Finalising the Conundrum....

Well,

A few things to report....

Firstly, when I was at the National HamFest the other weekend, I found myself a signal generator. It's a HP8648A and looks like this:


It covers 100KHz up to 1GHz and appears to be calibrated in agreement with my Spectrum Analyser. That's good enough for me and at last I have a Signal Generator where I can specify the output amplitude in dBm!

I've been fiddling today with the transverter project I started back here:

http://g0mgx.blogspot.co.uk/2014/09/to-transvert-or-not-to-transvert.html

and have been making the final component which is a 10W PA to give a reasonable level or RF out. Here's what the PA looks like:


It's based on a 2SC2539 final transistor which is mounted on a reasonable heatsync between the two copper boards you can see. The PA seems to be working with a nice clean output:


The driver transistor (which is a poor old 2N3866) is running hot, hot, hot! I need to find a better component for that bit as otherwise it's going to cook. Something with an isolated can would be ideal so I can solder it to the copper board - that would make an excellent heatsync.

I've stuck the project together now and it's looking like this:


I need to run some more tests on the output to check for harmonics and other spurious emissions, but I think this is good for an on-air test now.

The only other thing to report is that I left my FT-DX3000 WSPRing on 40M last night, I set the RF out to the lowest setting (5W) but also reduced the audio drive so the output was reading 2W on the internal meter. This is the map of heard/hearing this morning:


Florrie cat's not been helping much, sleeping behind the radio PC monitor:


The other three spent most of the afternoon upside down in the kitchen:


Good, egh?

Local conditions.

Friday, 3 October 2014

WSPRing again - Shhhhhh

Well,

Before I headed off to the work QTH yesterday, I left one of the radios in WSPR on 20M. Here's what I found when I got home:


Now, none of these can be considered QSOs but it sure gives a good impression of the propagation through the day and the station capability.

I'm more than impressed.

Good, egh?

Tuesday, 30 September 2014

A White Stick?

Well,

Been fiddling with a new antenna today; I bought it from "My Favorite Ham Store" LAM Communications. I only ordered it yesterday afternoon, and it duly arrived this morning by FedEx:

LAM Communications

This antenna is a "White Stick" made by Diamond Antennas and is designed to work on 6M (50Mhz), 2M (144MHz) and 70cm (433MHz).

As I have no antenna analyser that will work on 2M or 70cm I have attached the antenna (now it's up in the air) to the Return Loss Bridge we made back here:

http://g0mgx.blogspot.co.uk/2013/09/so-whats-happened-to-bridge-then.html

and also to a commercial Rigol RLB I have. Both gave almost identical results when using the Spectrum Analyser in SWR mode.

Here's what we see on 50MHz:


You can see a clear resonant point at 51.47MHz with a return loss of 23dB and an SWR of 1:1.15 (ish) - most excellent.

Here's what we see on 144MHz:


An almost identical clear resonant point, this time at 145.04MHz with a return loss of 34.9dB and an SWR of 1:1.03 - again most excellent.

Here's what we see at 433MHz:


Now this shows that the antenna is resonant way wider than the whole of the 70cm band - the measurements at 433.5MHz are 12.8dB return loss which is an SWR of 1:1.5 - again that's perfectly acceptable.

The antenna included a wire radial for 50MHz which I simply attached to the mast and a SWR adjustment which I just stuck in the middle.

Cats didn't help much, too busy waiting for tea:



Good egh?

Local conditions.

Sunday, 28 September 2014

How much RTTY?

Well,

This weekend was the CQ WW RTTY Contest - by far the granddaddy of all RTTY contests with wall to wall RTTY signals on the bands.

I've had a dabble, and here is my log as a map:


Fun. egh?

Monday, 22 September 2014

It's a 4 hour sprint!

Well,

Last night was the BARTG 75 baud RTTY September sprint contest.

It's only a 4 hour test so even my boredom levels coped well with this one. 75 baud RTTY is quite odd really as I suspect I spend as much time thinking about what just happened as I save by the transmissions being faster. Net result is just more confusion on my part!

Anyhow, I have entered my meagre efforts into the contest, here's my log as a map:


Meanwhile, Chopsy has a new hidey hole:


And Pepper has found a transformer to perch on:



Fun, egh?

Saturday, 20 September 2014

The Continuation of the Transverting Conundrum

Well,

I've been fiddling some more with my experimental 4M Transverter project.

I've built the RX converter:


This is fairly simple in that it takes the 70MHz signals from the antenna, amplifies them and then mixes them with the 60MHz local oscillator we developed last time:

http://g0mgx.blogspot.co.uk/2014/09/to-transvert-or-not-to-transvert.html

and results in a 10MHz signal at the output. I've done some initial tests on this down converter and it seems to work as expected.

The transmit side is still work in progress:


On the right you can see part of a traditional doubly balanced mixer - I've used BAT85 diodes this time for a change.

The mixer mixes the 10MHz drive signal with the 60MHz local oscillator to make the 70MHz (plus all the harmonics and also the difference). This is fed through a band pass filter, which sweeps like this:


and then amplified and passed through another filter. The second filter is also a band pass at the moment, but I expect I will swap it for an identical low pass filter I made for the RX side - the second band pass filter is no way near as good as the first for some reason.

I then need to make a linear amplifier to increase the output to about 10W to drive my linear.

Good, egh?