Wednesday 10 March 2010

Radford Labpack and 80m WSPR results

Last night we had an auction of equipment from an SK member at the club. I wanted the AVO RF Generator - but it got too rich for me! Fortunately, another item I wanted had been incorrectly catalogued as a "Universal Bridge". I recognized it as a Radford "Labpack" power supply unit and picked it up for £15.

I recognized it because I've had another one on loan here in the shack from my friend Mark. Here's Mark's unit (at rear) and my new acquisition ...

You might just be able to make out that Mark's unit is a slightly different model than mine - his voltage selector is on the front panel (mine is inside, accessed by a screwdriver through a hole in the back of the case). Mine also has its handles in place.

I did a bit of sniffing around on the net and discovered that there were other models of Labpack - including this (obviously older) model (click on the picture to see it at full size on a nice website about Radford)...

I learned that Arthur Radford, G6YA, pretty much started his business with the Labpack, before going on to develop the audio products we remember him for. In addition to the STA 12 and STA 25 amplifiers (sadly not in the m0xpd collection) I remember some nice low distortion AF oscillators and distortion test kit bearing the Radford brand. Also, my old friend George "the Greek" had a nice Radford pre-amplifier. Anyway - that's enough of a stroll down memory lane - back to the Labpack.

The Labpack is a useful, unregulated variable power supply, built like a battleship. Nothing too remarkable about that - but the attraction for me is that it includes a healthy 6.3V heater supply and 300Vdc. In other words, it is perfect for my valve-based games!

The full complement of outputs is as follows...

OutputVoltage (V)Current (A)
Variable d.c.0-308
Variable a.c.0-308
Fixed a.c.6.33
Fixed a.c.128

When I first built my Paraset the Labpack was the only HT supply I had (thanks Mark). Since then, I've made a PSU for the Paraset using a transformer rescued from a dead Telequipment 'scope, seen here on the bench (under a 12V power supply which also came from Mark)...

This homebrew supply has the luxury of an ammeter on the HT supply, so I can monitor plate current. I also have the inverter made for lower-power projects.

Despite these other options for HT, the new Labpack is a welcome addition to the bench and will allow me to give Mark his unit back!

While I'm in blogging mode...

my recent whispering on 80m was stopped abruptly when Bill Gates (of fond memory) insisted that my computer should perform an automatic update. The results were not as inspiring as for 40m - best spot was SM0FLY at a distance of 1391 km - still not bad for my half G5RV (with inductors) and 500mW!

...-.- de m0xpd

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