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.)

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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