EMRFD Message Archive 4230

Message Date From Subject
4230 2010-02-09 05:57:46 Nick Kennedy Re: CA3046 squarer
Another interesting and unusual CA3046 application I happened across
recently is the squarer circuit in the QRP Quarterly, Fall 2009 page
13. Steve Weber uses this circuit to linearize the meter scale of a
wattmeter. Said he based it on a National Semiconductor application
note.

I'm tempted to add it to my little QRP SWR / wattmeter (EMRFD tie-in:
see W7EL's "A Simple and Accurate QRP Directional Wattmeter on your CD
or QST 2/1990).

72- Nick, WA5BDU
4231 2010-02-09 06:02:49 Vaclav Peroutka Re: [emrfd] CA3046 squarer
> Another interesting and unusual CA3046 application I happened across
> recently is the squarer circuit in the QRP Quarterly, Fall 2009 page
> 13. Steve Weber uses this circuit to linearize the meter scale of a
> wattmeter. Said he based it on a National Semiconductor application
> note.
>
> I'm tempted to add it to my little QRP SWR / wattmeter (EMRFD tie-in:
> see W7EL's "A Simple and Accurate QRP Directional Wattmeter on your CD
> or QST 2/1990).
>
> 72- Nick, WA5BDU
>

Hi Nick,

is it the same as on this web page ?
http://kd1jv.qrpradio.com/lspwmtr/linear_analog_SWR_meter.HTM

Vaclav
4232 2010-02-09 06:33:29 Chris Trask Re: CA3046 squarer
>
> > Another interesting and unusual CA3046 application I happened across
> > recently is the squarer circuit in the QRP Quarterly, Fall 2009 page
> > 13. Steve Weber uses this circuit to linearize the meter scale of a
> > wattmeter. Said he based it on a National Semiconductor application
> > note.
> >
> > I'm tempted to add it to my little QRP SWR / wattmeter (EMRFD tie-in:
> > see W7EL's "A Simple and Accurate QRP Directional Wattmeter on your CD
> > or QST 2/1990).
> >
> > 72- Nick, WA5BDU
> >
>
> Hi Nick,
>
> is it the same as on this web page ?
> http://kd1jv.qrpradio.com/lspwmtr/linear_analog_SWR_meter.HTM
>

That's interesting, provided that you ground pin 13.

You can use the CA3046 together with a low offset quad opamp to make a
linear analogue multiplier. Look at the datasheet and applications for the
RC4200* analog multiplier and you can see how to do it. I've made CA3046
equivalents of this just for fun in the past, though I use the AD633 now.
Too bad the RC4200 went out of produvtion. It had a 10MHz bandwidth and
would work with single supplies. I also miss the XR2208 as it included a
small opamp.

Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/