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Thursday, 16 November 2017

Another PSU!

Well,

I've been fiddling today and have made myself another bench PSU.

I was looking for a 28V supply the other day, so I've knocked up something to give me a 28V, 12V and variable output.

The 28V line is a simple LM317 - there are plenty of calculators for that voltage regulator on line.

The 12V line is simply a 7812 regulator, I think I need to add a big heatsync through because the power dissipation at 500 mA will be 22 - 12 = 10V * 0.5 = 5W so its going to run quite hot.

The variable supply gives an adjustable output between about 2.5V and 15V; it's based on my favorite the old lm723:


The first pass transistor is a BD139 and then the main one is a TIP3055.

The current limiting is dictated by the voltage between pins 2 and 3 so we have a 0.1R resistor there on the main high current path, the voltage difference needs to be 0.6V to initiate the current limit so using ohms law we can easily calculate that the current limiting will happen at 0.6V/0.1R = 6A.

There's a really nice toroidal transformer which will deliver plenty of current.

It's all a bit of a bodge:


The case looks OK:



It's not bad for a few hours work. The bench looks like a bomb has hit it:


good, egh?

Friday, 10 November 2017

A bit more top band

Well,

Following the antenna I originally made here and then replaced here, I've been fiddling with the earthing arrangement for the system.

I've added some counterpoise wires which I have stapled to the fence and various other bits and bobs in the garden.

I've then made an artificial earth/counterpoise tuner thingamabob, much like this thing back here, and mounted it at the base of the antenna between the earth rods and the radials:



And then adjusted the capacitor for maximum smoke on top band when TXing.

There's quite a lot of current flowing, what improvement it makes I dont know.

Here's a map of FT8 and CW QSOs I've made on top band since the changes to the antenna:


Chopsey Cat (AKA Git Bastard Cat from Hell) is asleep in the conservatory:


whereas Maggie and Florrie Cat are tucked up in one of the dogs beds:


Local conditions.


Friday, 27 October 2017

GB3ZME - Loud and Proud

Well,

Just been looking around on 13cm and testing a few things.

The beacon at Telford is loud this morning:



Local conditions.

I found an issue with my 13cm Amplifier; I've updated the post here accordingly.

Friday, 20 October 2017

The Ultimate 3

Well,

Quite some time ago, I built myself an Ultimate 3 QRSS/WSPR beacon kit from QRP Labs.

Now this is a fab and groovy kit from the infamous Mr Hans Summers.

The completed kit is currently sat atop of my FT-817 and is configured to send WSPR beacon and a QRSS beacon both on the 30M band.

The output of the unit looks like this:


and is 13.12V peak to peak.

That's a power output of 420.2 mW or 26.3 dBm.


So, I've left this running for 24 hours connected to a simple 30M dipole in the garden, and here's the WSPR map of the resultant reception of my signal:


Never fails to amaze.

And here is my very beautiful Bonnie Dog:


Local conditions.

Thursday, 19 October 2017

Three holes in the ground (well, well, well)

Well,

I just found out, very much by accident, that one of my 'scopes has a built in "Easter Egg" in that you can play Tetris on it!


After power on, press Print/Utility and then hold down function keys 2&3 - voila!

Bonkers.

Friday, 8 September 2017

The Art of Rotator Control

Well,

I decided that there had to be an easy way to computer control my antenna rotators. I already have this on the Satellite antennas in Azimuth and Elevation, but not the "normal" antennas I have here for HF & VHF.

I looked on the big bad internet and found that Yaesu make a rotator interface for the G-1000 rotators that I have, but they are a simply staggering price.

So, there had to be a way....

The first thing I did was connect to the interface socket on the back of the rotator and figure out which pin did what. We have a voltage output that represents the heading, which plotted like this:


Using simple bit of maths we can then create an equation to calculate the voltage at any heading (to save me having to keep moving the antennas back and forth):


There are also two pins on the interface connector that you ground to turn the rotor left and right. There's also a fourth pin you can use to set the rotator speed.

I then figured that Arduino was certainly the way to go, but then I found this:

https://blog.radioartisan.com/yaesu-rotator-computer-serial-interface/

Now, this interface does all I want and a million things more, it's been written in a way that allows you to configure the bits you want and exclude the bits you don't.

To get this to work with my G-1000 series rotator, I configured the following:

#define AZIMUTH_STARTING_POINT_DEFAULT 0

in the rotator_settings.h file; that's about it!

That setting defines the rotator as one that turns around 0 degrees (rather than 180 being the end stop).

Once I had done that and defined the pins (I just used the defaults) and also defined Digital pin 10 as the speed output:

#define azimuth_speed_voltage 10

in the rotator_pins.h file

I compiled the code for a Arduino Nano with an ATMega328 processor (because that is what I had lying around).

I then built the simple interface needed:


Now, the next step was to calibrate the software. Instead of turning the rotator from fully CCW to fully CW (including the 90 degree overlap), I just used the equation I established above to calculate the voltage and set the bench PSU to deliver same.


Then once that was complete, I connected the Arduino board to my Radio Control PC, fought with COM port settings (a favorite hobby of mine) and then configured my logging software to use a rotator controller emulating the Yaesu GS-232B command set.


So now I have this display above, it shows where the antennas are pointing and allows me to click on a heading to send the antennas there. I can also configure the system to auto turn the rotator based on selection of DX spot if I like too.

Neat, egh?

Sunday, 3 September 2017

I'm forever blowing bubbles? No! bulbs!

Well,

I have a couple of Yaesu Rotators here, and the controllers were stacked one on top of the other with a small cardboard box propping up the top controller. The cases are kind of slanty topped and the whole arrangement meant that they both fell to the desk regularly. This in turn ensured that the bulbs illuminating the front scale blew farily soon after purchase.

My local friendly emporium LAM Communications sent me some replacement bulbs some time ago, I just never got round to replacing them - mainly because I couldn't find any instruction on how to do so.

So, here's how to replace the bulbs in a Yaesu Rotatorbamob (or certainly the 1000DXC variety).

Firstly we remove the main external case:



Now, the bulb is clearly part of the main dial thingy on the front, so that had to be removed also (there are 4 screws):



The bulb is under the silver paper I've highlighted below:


So it's just a case of peeling back the tape carefully, and soldering in a new bulb.

I've also made a wooden stand thingy so the controllers stack without the need for cardboard wedges and other jiggery-pokery and hopefully the wont fall over any more:


Local conditions.