Get a "load" of this

[Radford Revival]

Decided I needed a better test load, so I built one.

A bit more versatile than just a big resistor on some binding posts, it has a few features:


Two completely independent channels, optionally paralleled with a switch
Each channel switchable between 3.75, 7.5, 15 and 30 ohms
BNC outputs for monitoring as well as 10:1 attenuated BNCs for all outputs
Outputs include a direct singled ended monitor, as well as two separately earthed outputs to monitor bridged amplifiers or perform impedance measurements with the load in series with the DUT.
Chassis earth brought out to a post to earth to where is strategic for the particular testing situation if noise issues crop up.


Each resistor is 50W rated and the heatsinks were salvaged from an old MOSFET PA amp. I don't intend to run the resistors near their power rating, if I did I would probably point a big fan at the thing.

The attenuated outputs have an output-Z of approx 900 ohms but this shouldn't pose an issue with a short run of coax to a scope or audio interface.


http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2017/03/dummy1.jpg


http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2017/03/dummy2.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2017/03/dummy3.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2017/03/dummy4.jpg

[struth]

Now thats a bit of kit. No holds barred quality.you could start a line of those

[walpurgis]

Neat. Like it. :)

[Radford Revival]

Now thats a bit of kit. No holds barred quality.you could start a line of those

Thank you :)

If I was making them for someone else I would do a few things a little differently - for one I would screw the resistors to the heatsink and use heatsink compound as opposed to using thermal glue ;)

[nthall]

I want one of those on my bench. It would save me a ton of time hooking up jumpers, and searching for adapters and probes.

Nice work!

Sent from my Z981 using Tapatalk

[Radford Revival]

I want one of those on my bench. It would save me a ton of time hooking up jumpers, and searching for adapters and probes.

Nice work!

Sent from my Z981 using Tapatalk

Indeed, it makes ones life much easier. This was long overdue.

[Firebottle]

Nice construction and great heatsinking. I like a good heatsink :mental:

[Radford Revival]

Nice construction and great heatsinking. I like a good heatsink :mental:

They should do the trick, I have no idea what their capacity is but I don't intend to drive this too hard anyway!

[Naughty Nigel]

Very nicely designed and put together.

I would happily pay for one of those. It almost looks as if it should have Tektronix stamped on the front panel. :)

If it were mine I would probably add a switched 2 µF capacitor to each channel to test amplifier stability, and possibly a moving coil meter to provide a rough indication of the amplifier's power output.

[337alant]

Excellent job Will and a very useful bit of kit :eyebrows:

Alan

[spendorman]

In the true Radford tradition to build their own test equipment.