Author Topic: Simple RF test set described  (Read 2668 times)

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Offline vk3yedotcomTopic starter

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Simple RF test set described
« on: August 28, 2012, 01:04:01 pm »
Just some forewarning of a piece of test gear of interest to RF tinkerers that could be a good project.  The general concept is a 'swiss army knife'. It's small, cheap and does a lot. But not necessarily particularly well.

Anyway it's described in the September 2012 Amateur Radio magazine available at many newsagents.  I manage to get 8 RF test functions from an instrument that uses just one IC, one transistor, one meter (and lots of switches).   As it stands it can measure RF power output, field strength (relative indication), CW, AM and SSB transmission quality and even generate signals on a few spot frequencies. Ideas on additional functions appreciated.

In that same issue is a simple ESR meter that will also interest a lot of people.  This uses an analogue meter and has a PCB layout (boards also available).
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Offline kg4arn

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Re: Simple RF test set described
« Reply #1 on: August 28, 2012, 09:11:03 pm »
Is it your circuit design?
 

Offline vk3yedotcomTopic starter

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Re: Simple RF test set described
« Reply #2 on: August 29, 2012, 11:02:04 am »
Is it your circuit design?

The unit is, but the stages are stock standard.

It's amazing how many things you can do with 3 or 4 stages.

An LM386 is used as either a DC amplifier (to drive a meter movement) or an audio amplifier (for a small speaker).  The latter is used for the signal monitor or audio signal tracer.

A diode rectifies RF to DC (or in some cases audio).

A crystal oscillator switched between a few frequencies provides some spot frequencies for receiver testing and a local oscillator for the SSB transmission monitor/WWV receiver.

A tuned circuit (variable over a couple of common HF ranges) is good for the absorbtion wavemeter and receiver.

And the meter movement gets use for the RF power meter/dummy load, field strength meter and absorbtion wavemeter.

About the hardest challenge was switching all these without too many switches and there were some compromises.

Though not the main subject of these videos, it get some use in them: 

« Last Edit: August 29, 2012, 12:57:44 pm by vk3yedotcom »
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