Sunday, December 13, 2009

Dec 2009 - Africa - Portable Operations.


Located about 100 miles north-east of the coastal city of Cape Town, our base camp is at 32.871954S, 19.084239E.
This time, we are exploring the mountainous region of the Ceder Mountains, adjacent to the Great Winterhoek Mountain Nature Reserve.
The base cabin is visible in the middle of the picture. A freshwater stream (which provides drinking water as well as a refreshing break from the daytime heat) runs about 100ft from the cabin.


Traveling here is easy by car (we bring 4X4 just in case), and at elevation of about 1500 MSL, we are surrounded by lots of mountains.
The cabin offers sleeping facilities for 6x. No electricity or water supply - just the way we like it. Well - ok - plenty of running water from the nearby river which serves as fresh water supply as well as a welcome relief from the baking southern sun.
At this location, the air is clean, there is no light pollution and at night, the Milky Way lights up the skies. While around the campfire, stargazing consumes the better half of the evening.
(No visible International Space Station pass during our stay unfortunately)



The "Green" Inverted V goes up - Mast is a sturdy piece of 30ft straight timber we found close to the cabin.




QRV / QRP - Of course no electrical infrastructure for miles, also means no rf pollution, and virtually "no" noise floor. With an inverted V for 40/20m, we light up the 706 (battery power). 20m dx sounds fill the quiet evening and even S1 signals are booming in Q5. What appears to be 20m short path to the U.S. comes alive around 20:00 UTC. No dx luck at QRP power levels, unfortunately, due to the high noise floors at the remote stations.

On 40m, local stations (< 1000 miles) provide for fun rag-chew QSO's during the daylight hours.



 Working local stations on QRP power offers quite a bit of activity during the daytime, with several fixed base and mobile stations from as far as Namibia and the Kruger National Park on 40m.


Stateside dx on 40m around 04:00 UTC are 5/9++. W1AW code bulletins are as clear as local stations during this window. 40m Gray line propagation shuts down around 06:30 UTC. Unfortunately we did not work any dx on 40m this time.



The rock formations in this area are truly spectacular, with a variety of freshwater streams feeding into the Elephant river. Easy hikes from base camp provide access to great vistas, waterfalls and freshwater mountain pools for cooling off during the summertime heat.


This time of year, the temperatures average about 30C. During our stay, we were lucky with some overcast days reaching 28C.



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Saturday, November 14, 2009

HF A/B linear on 20m - 15W PSK

With the LPF inline and on higher bande, such as on 20m this amps' performance drops a little but still delivers 15W easily with 1W drive.

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Homebrew 40W WA2EBY linear amp.

After soldering in the header to support LPF/plug-ins the homebrew Hf-packer amp finally made it into an enclosure. Nothing permanent for now, but at least it'll keep some of the rf inside the box. The 2 x IRF510 MOSFETS are visible mounted on heatsink.
The amp delivers 40W output with 1W drive - at 24 Vcc.


The heatsink is pobably a little overkill, but it works! The IRF510's are heating up quite a bit at 20W.
This al enclosure (designed for rf use) was a find at the local surplus store for $5. It came with pre-drilled openings for DB9-style panel mounts - which now double as BNC mount slots.

The lid + heatsink still sitting loose on-top...and I'll have to do better job of running shielded cable to the MOSFETs. (hidden from view here under the heatsink)

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Sunday, November 8, 2009

ARRL CW SS : 40m

Zooming into the activity shows the signal spacing around 100Hz
Detecting light signals on this busy band is no problem - Rocky S/W, (with narrow filters still usable to around 35Hz on CW.)

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40m ARRL CW Sweepstakes. Busy band


Spacing down to 200Hz in cases
ARRL CW Sweepstakes on 40m.
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2009 ARRL CW Sweepstakes - 40m

So the 2009 ARRL CW Sweepstakes is in full progress and the 40m band is packed. Here are some screenshots showing the activity.
Radio: Softrock 6.3 txrx, Antenna : Wire vertical at sea level.

The entire 7.0 - 7.1 full of CW - what a joy!


Think we can get a QRP 1W signal in there. Actually yes - the contest stations are so keen for points, and the QRP class (up to 5Watts) is definitely active and recognized in this competition.


Zoom into the activity shows the signals about 200Hz apart. Using the Rocky S/W, it's easy to filter out the big signals, and still copy the weaker stations among them.
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Saturday, November 7, 2009

PSK31 with Rocky and Softrock 6.3.

Zoomed view of what Rocky can provide, with signals close to each other on the waterfall. Operating PSK directly from the Panadapter is very convenient, and provides a wide-band view while providing the ability to filter down to a usable 25Hz.
Rocky supports demodulation of SSB, CW and PSK31.  It also transmits in CW and PSK31.  It's PSK31 decoder offers exceptional quality...and combined with the Softrock, this platform provides for hours of fun experiments, and trying out different antenna options. 
With the panadapter view of 96KHz (depending on your soundcard) this system can be a very effective tool in antenna experiements.  Signal to noise ratios are now easily visible, and "watching " the band adds a different dimension to hf-monitoring. 
Rocky also allows recording of the entire 96KHz spectrum for later play-back. 


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WA2EBY - HF AB linear amp.

Prototyping the WA2EBY broadband amplifier. Using 2 x IRF510 MOSFETs this design is capable of about 16dB gain when supplied with 24V. (1 W in, 40W out) (Output board on the left and Input and TX switching on the right. The heatsink with the 2 x IRF 510's is out of view here. (QST March/April 1999.) http://www.golddredgervideo.com/kc0wox/wa2ebyamp/

This is the output board - which has the phasing transformer (right) as well as the output balun (left). The rest is the 5V bias supply.

Input circuit, with 1:1 input balun (bottom right) TX relay in the back. Left is 5V bias adjust circuit, driving the MOSFETS in AB mode.
The LPF is fittend in the output to the antenna, and be sure to measure for harmonic suppression before connecting to an antenna.
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2009 ARRL CW SS - More fun.

With SDR it is really easy to apply very narrow filters. Here is a view of the very close-spaces 20m CW signals. See how many you can count within 1KHz of each other.

Zooming out slightly - gives a good view of the level of activity on 20m
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ARRL 2009 - CW Sweepstakes



Busy 20m band on 7 Nov 2009 - with the ARRL CW Sweepstakes in full swing. Softrock 6.3 TXRX with 20m Vertical dipole.
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Saturday, October 31, 2009

Homebrew 5 W linear amplifier for the Softrock SDR


Enough of this QRPp!  Now that we know the radio works for sure,  lets add some power for those QSB moments.
The 5W amp is in progress and being tested on 40/20m. First tests into dummy load show about 3- 5W out with 1W of drive. Using NB6M's "miniboots" design, here goes,  and "yes I know this really needs to go on copper" with proper shielding.

Notice the LPF is already inline, and output reads close to 5W / CW (with 1W drive from the Softrock SDR)
Parts for this 5W amplifier will run you about $8-$10 depending on where you source your components.
Adding several LPF's for each band combination will require mode capacitors and toroid inductors. 
The most expensive part (in my case) was the relay (DPDT tx relay switch) at about $2.50. The amplifier design is based on the very popular and very affordable IFR510 MOSFET.  Add your choice of LPF for the output stage and make sure to mearure for harmonic suppression.

Be sure to measure for proper harmonic suppression with the LPF inline.  A good IMD test can be performed using Rocky's built-in 2-tone generator.

Miniboots reference: http://www.amqrp.org/kits/miniboots/miniboot.htm
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Softrock 6.3 nearing completion.

Oh - the joy of SMT.  With the Softrock 6.3 kit, theres a few more interesting hours of soldering ahead.  The double sided board, has al lthe smt on the bottom.  Here the board is taking shape, wiht the PSU and some initial smt components, including the VXLO in place.

Here the board is nearing completion with the LPF inplace and all the components in place.  The bottom has a few more smt's added to the mix.




A few headers make the external connections a breeze.  This way you can work on the boad, make corrections without worrying about damaging the external wiring already soldered in place.

And so the first day on-air arrives.   With things wrapped up and headers all wired, the radio can get on the air. This time with a 20m quaterwave vertical (wire) antenna no higher than 20ft. Sitting on the antenna tuner, one can easily watch for smoke, while ensuring there's a nice match.
Given the space limitations at my QTH, I choose to make sure things are matches by adding the antenna tuner.  The Softrock earning it's place in the "shack with a view". 
Here goes with a few CQ's on PSK31 (20m)

What do you know -the signal makes it over to the east-coast.  Software:  Rocky, Antenna = wire vertical at sea level.

And after a few hours of calling CQ - the results look like this.

Softrock txrx 6.3 (1W) nearly completed

The Softrock 6.3 txrx kit will test a few more of your smt skills, but with a little persistence and after a few hours of building, the board is coming together nicely. The main board acts as motherboard for the rx BPF's as well as multiple Power Amps. The PA modules can be purchased separate for each band-combination you require (eg. 40/80, 30 - 17, 15 - 10) The smt components on this design is all mounted on the reverse side with through hole components on the top. Tony's design is very good and so is the quality of the manufacturing of the boards. As always with kits and projects, once you start, the thing has to get done, and you can't wait to get it on-air. No different here.
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Tuesday, June 23, 2009

SDR with the SoftRock Lite II kit.


It felt as if I was missing out on the action of age of Sotfware Defined Radio . So I decided to get going with a Kit and completed the SoftRock Lite II in a few hours. The SMT is a little tricky, but for a first try I must say it requires nothing more than basic soldering skills and very good tools for visually inspecting your work.

So I ordered a SoftRock Lite II 40m kit.
The package arrived in the mail 2 days later, and I could not wait to get started on the construction.
You can read a write-up of the construction project here

I could not wait to get this radio on the air, so the construction went into the early morning hours one night. After about 4 hours (of which the toughest is the minute toroids) the project was on the air, and alive.

The SMT work is really no big deal, and allthough parts are tiny, good viewing tools make the project go much faster.

This board matches the performance of the other expensive radio I own.
This may just be the best $10 you ever spent on ham gear.

Using PSK Reporter is a really helpful system for tracking propagation.
Here is a sample of what my 20m SDR receiver sees during a 24 hr cycle.

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Tuesday, March 31, 2009

2009: CQ WPX SSB: Anza-Borrego State Park.

The area is green after the rains - mild temps and rfi-free
environment, makes for fun HF portable operations.