EMRFD Message Archive 8766

Message Date From Subject
8766 2013-06-27 14:25:27 Paolo Mattiolo Minimal SWR Indicator
Hello, I'm In3aqk from italy.

I need a really simple swr indicator, possible based only on a led ed few components.
I need it for a qrp transceiver TJ2A that I'm going to finish in few days.

On this link it's possible to see the schematic of the final stage of the tj2a:


There is really no space left in the case and I need only an indication of mismatch.
I already have an external microswr but i prefer to enclose a simple indicatore inside the rig.

The TJ2A is a qrp rig so, the maximum power is about 2-4 watts on 20 and 40 meters.

Unfortunately I've not the old issues of sprat, probably a minimal led based swr indicator was already published.

Thanks for all the advice.

73 de in3aqk
8767 2013-06-27 14:33:33 Tony Fishpool Re: Minimal SWR Indicator
Paolo, Have a look at http://www.gqrp.com/resistive_swr_bridge.pdf and
consider changing the meter for an LED.

Kind regards
Tony G4WIF

-----Original Message-----
8770 2013-06-28 01:08:54 Nick Kennedy Re: Minimal SWR Indicator
Probably about the same as the one Tony linked, here's one by Dan Tayloe.
I think it's currently offered as a kit from Hendricks' QRPKits


Uses an LED for indication. A nice feature of the resistive bridge method
is that you never subject your transmitter to over 2:1 SWR, IIRC.

Here you'll see one I built into an EFHW tuner box.


Nick, WA5BDU

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